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Fennel growing season


Growing fennel — bulb, herb, pollen

By Pam Dawling. Pam is the garden manager at Twin Oaks Community in central Virginia. Her book, Sustainable Market Farming: Intensive Vegetable Production on a Few Acres, is available from Growing for Market. Subscribers always get 20% off books when they are logged in. Pam's blog is at sustainablemarketfarming.com.

This article originally ran in the April 2013 issue of Growing for Market Magazine.

Many people grow fennel as the herb, for leaves and seeds, for salads, soups, fish dishes and teas. The seeds are also used in desserts, breads, other baked goods and drinks. Or they are chewed after a meal to help the digestion. A newer crop in the U.S. is bulb fennel, with a vaguely licorice-like flavor. The crunchy white “bulb” consists of the swollen stem bases of the leaves. Fennel is also used in the seedling stage as a microgreen or baby salad mix ingredient. And even newer and more “exotic” is fennel pollen. Although this crop is used in so many forms, the basic details are the same for all types, so I’ll start with those.


Bulb fennel on display at a farmers market. Photo by Nikki Warner.

Crop requirements
Fennel benefits from a rich, well-drained soil, with a pH of 5.5-6.8. Plant in a sunny spot for best results. Bear in mind that fennel is a Mediterranean crop, a cool-weather short-lived perennial normally grown as an annual. Fennel survives light frosts, but will only survive over winter outdoors (assuming you didn’t harvest the bulb) in zones 6-10. In zones 2-5 it grows as a biennial. It tolerates some heat and cold, but does best when it reaches maturity in cool weather. Depending on your climate, seed may be sown in early spring, mid-spring, late summer and early fall. Fennel grown for bulbs will not provide seed too – to get succulent bulbs, grow the plant fast, harvest before flower stems form and provide plenty of water. If water is in short supply, put bulb fennel at the top of your watering list.

There are about 200 seeds per gram, 7,000 seeds per ounce.  The average direct seeding rate is 1000 seeds/100', 700'/ounce, or an average of 4,000 transplants/ounce of seed. Each diner could eat up to five fennel bulbs over a season.

Fennel is not troubled by many insect pests or diseases. You might find aphids or whiteflies on the leaves, but they are rarely a serious problem. Slugs can be trouble. The worst disease is root rot, which can happen if your plants get waterlogged for too long. I’ve been emphasizing the importance of enough irrigation, but don’t over-water!

Sowing
To germinate fennel successfully, the seeds must be in the dark, with a soil temperature of 60-90°F. (70°F is ideal.) Direct seed at 10 seeds/ft, in rows 18" apart. Thin the seedlings to 6-12" apart. Or station sow the seed, dropping three seeds together at 12” intervals along the row, later thinning to leave the strongest seedling at each station. If the soil is dry when you are sowing, soak the furrow first.  Cover the seeds with 1/8-1/2” of soil. They will take about 7-10 days to emerge. To improve germination, try soaking and pre-sprouting the seed for several days.

Bulb fennel can be sown outdoors as early as 2-5 weeks before the average last frost date in spring, but when the danger of hard frost (28°F) is over. Beware - early spring sowings are more likely to bolt. Bulb fennel is sensitive not only to day-length, but it may also bolt if there is a sudden chill (a temperature reversal). Here in zone 7, we sow Zefa Fino March 10, for April 10-26 transplanting, along an edge of a bed with parsnips, celery and (later) asparagus beans. The transplanting date is around our last frost date. If your climate and timing give you the choice, direct sow and thin, rather than transplanting, to reduce the likelihood of bolting.

The best time to sow bulb fennel is for an autumn crop. Sow in mid- to late-summer, calculating the sowing date by working back from your hoped-for harvest date. Your last sowing date will be 90-110 days before your first fall frost. In northern latitudes, gardeners wait till the summer solstice to sow any bulb fennel. If you sow around the middle of June, you should be harvesting bulbs in mid-October. The bulbs can survive a frost or two, so there is no rush to harvest when cold weather arrives. We aim to direct sow on July 8, and July 28, in part of a carrot bed. This way we keep the fennel with its umbelliferae cousins, and make our crop rotation easier.

Transplanting
Transplanting is useful in areas with short springs, or short seasons overall. Fennel is said to dislike root disturbance, so if transplanting, use plugs or modules. Sow 3 seeds/cell, 1/4" deep, in 1.5-2" deep cells. Thin to 1 plant/cell. Transplant outdoors in mid-spring to late summer when plants are 3-4” tall, and 4-6 weeks old, before they become root-bound, and when they can be removed easily without disturbing the roots. Final spacing should be 6-12” apart, either in single rows, or in rows 18” apart. Do not crowd bulb fennel plants, especially in spring, or you will encourage bolting. The plants will grow 36” tall or more, and the stems and delicate foliage can be eaten or made into teas. Herb fennel may grow to 60”.

Varieties of bulb fennel
For fennel bulbs, also known as finocchio, or Florence Fennel, sowings after mid-summer have a better chance than spring ones of producing fat tender juicy bulbs, partly due to wetter weather as the bulbs mature, and partly as they do not having lengthening daylight to induce bolting.

For earliness, try Montebianco (mid-size round white bulb, solid stalks), Mantovano, (75-85 days, round very white large bulbs), or Parma Sel Prado, (round white smallish bulbs). All from Seeds from Italy.

Some varieties do much better in the fall: try Mantovano, Bianco Perfezione Sel Fano (80-85 days, good size, half-hollow stem) from Seeds from Italy, or Victorio (75 days) from Territorial Seeds.

For spring as well as fall, try Romanesco, (85 days, a large classic variety with thick tightly wrapped stems), generic  Florence Fennel (90 days),  Zefa Fino (80 days) or Trieste (90 days), a bolt-resistant hybrid from Renee's Garden.

Zefa Fino is more tolerant of stress than some of the traditional Italian varieties, so if your climate or timing is borderline, try this one.

Preludio and Orazio (both 80 days) are F1 hybrids from Johnny’s Selected Seeds, that have a higher yield potential than open pollinated fennels. (All the others I have mentioned, except Trieste,  are OPs)

For cooler climates, try Victorio.

The two seasons for planting bulb fennel in zone 7 are March-April and July-August – the same dates that work for broccoli, beets and other cool weather crops. Bulb fennel is a seasonal treat that can be harvested for several weeks, but it is not a year-round vegetable in most climates. It is hardy to 15°F. If bulb fennel is new crop for you, experiment with several varieties and with sowing dates that match your other cool weather crops. The fall crop is likely to be more successful than a spring one. If your spring crop bolts before forming a good bulb, the feedback is that your weather is too hot for spring planting, so stick to fall crops in future, unless you can safely start earlier in the spring.

Bulb fennel vareities put more of their energy into the bulb than the leaves or flowers, and should be used when the bulb is what will be marketed.

Cultivation
Rich, well-drained soil, regularly irrigated, and cool temperatures produce top quality bulbs. Plants grow best and the flavors are superior when daytime air temperatures are 60-70°F. Start to blanch the lower stems when the bulb is the size of an egg by hilling up soil around the bulb. Mulching (with organic materials such as straw or hay) can be a good strategy to trap soil moisture and cooler temperatures in spring – the bulbs will be sweeter and more tender. Clip off any seed stalks that start to grow. The bulbs will be ready about three weeks after reaching egg size.

Harvest and postharvest
The bulbs are harvested when they get to small tennis ball size. If you leave them to grow larger, the plants will probably bolt and the flavor of the bulbs will quickly become bitter. Use a sharp knife or pruners to cut the bulb free just above taproot, right at the soil line. Trim the leaf stems about 1-2" above the bulb to prepare it for sale or storage. Bulb fennel requires 80-115 frost-free days to reach harvest.

Bulb fennel will keep in the refrigerator up to 1 week or in a cold moist place for 2 to 3 months. Best storage conditions are 32°F with 95% relative humidity. Stalks can be dried or frozen; leaves can be frozen or dried as herbs. Dried leaves should be stored in an airtight container.

For more on postharvest handling for a variety of vegetables, read our article "Beat the heat in postharvest handling."

Nutrition and cooking
Bulb fennel is high in vitamin C, and is also a good source of calcium, fiber and potassium. According to Southern Exposure Seed Exchange www.southernexposure.com, medicinally, fennel stimulates digestion while reducing the likelihood of flatulence. It is anti-spasmodic and anti-inflammatory. It can be used to soothe bronchial coughs in the same way that dill can. It has estrogenic properties to stimulate milk flow in nursing mothers.
 Because it is an uncommon crop in this country, it is probably wise to offer your customers some guidelines on how to prepare and eat it. Fennel bulbs can be eaten raw, sliced thin, in salads or with dips. They are good grilled, sautéed, or steamed whole or sliced. They are delicious boiled and served with cheese sauce or butter. Try roasting with olive oil.

Herb fennel
Fennel plants are attractive to butterflies, ladybugs, lacewings and pollinators. They can grow to 5’ tall, so plan accordingly. Herb fennels will not produce bulbs. Seeds may be direct sown or transplanted, as for bulb fennel. The color of the small seedlings of bronze fennel renders them almost invisible, so take care when weeding. Bronze fennel has thin stems and beautiful bronze feathery foliage, good for flower arrangements as well as salads and plate décor. It takes about 65 days from sowing to harvestable size. The green leaf type is even easier and up to ten days quicker to grow. Johnny’s sells a green and bronze mix. Fennel can be overwintered in mild areas (Zones 7-10) to provide seed the second summer.

The feathery foliage has a sweet anise flavor and is a tasty addition to salads, cole slaw, and dressings. To dry the leaves, bunch them and hang in a dry well-ventilated area – good air circulation is essential for success. Check the leaves for dryness once a week, for two to four weeks, until they are brittle, then crumble and store in a cool dark place.

Varieties of fennel that put more of their energy into making leaves and flowers are called leaf or herb fennel, and should be used instead of bulb fennel if bunches of leaves or flowers are the desired end product. Of course you can still use the leaves and flowers from bulb fennel in a pinch, bulb fennel just won't make as many of the aerial parts of the plant as leaf or herb fennel.

Fennel seed
Fennel seeds are used in teas and tinctures as a digestive aid, expectorant, and a tonic for the spleen, kidneys, and reproductive system. For seeds, try Finocchio Selvatico — Wild Fennel (75 days) from Seeds from Italy, www.growitalian.com. The seeds are superior to those of cultivated varieties, and the flowers are beautiful too. Johnny’s warns that too much moisture at bloom time can prevent the formation of a good crop of seeds. The seeds shed very easily, and you may not want a zillion fennel plants next year, so consider tying paper or cloth bags over the heads, before they shed.

To dry fennel seeds, wait for the flowers to turn brown. Spread the freshly gathered seeds (plump and grey-green) in a single layer on a horizontal window screen. Keep mice away. The seeds should be fully dry (and brown-green in color) in about two weeks. Store in a cool dry place.

Fennel does not cross with anything except other fennel. It is widely said (even by some seed companies!) that dill and fennel cross, and some even describe the terrible flavor of the resulting crosses.

Microgreens and flowers
The feathery seedlings make an attractive ingredient for microgreen mixes and plate garnishes. Johnny’s sells a special variety called Grosfruchtiger for microgreens, although any kind can be used. For more on microgreens, read our article "How to grow microgreens." 

In addition to producing pollen, fennel flowers come in small clusters that many beneficial insects like ladybugs like to feed upon.


Fennel pollen
Fennel pollen has recently been rediscovered as a flavor enhancer. Only a sprinkling is needed. It sells for $15/ounce, and is sometimes sold combined with salt. If you have the market, or can create it, why not try growing and collecting your own? 

In places like California where fennel is invasive and now grows wild, it might be possible to source fennel pollen from feral patches, instead of letting it go to flower on your farm. On the other hand, there's a pretty good chance that if you grow fennel on your farm, it will go to seed at some point, and here's how to harvest it.

Cut the fennel flower stems at 6-8”, bundle and tie 15-20 together. Cover the heads with paper bags leaving about 1” of stem sticking out of the bags. Tie the bags closed and hang them in a cool, dark and dry area with the stems pointing up. Use fans if needed. Tap the sides of the bags every couple of days for two weeks as the flowers dry.

When the flowers seem dry, shake the bag vigorously. Carefully open the bags and untie the bundles. Tap each individual flower head on the side of the bag as you remove it. Tip the fennel pollen and other plant matter from the bag into a fine mesh strainer resting over a bowl or bucket. Sift the pollen through the sieve, to remove the other plant matter and the larger tiny wildlife. If you need to kill any teeny tiny wildlife, you can microwave the pollen for 10 seconds.

Each flower head will produce about 1/4 tsp. of pollen. Collecting one ounce can take an hour, so a selling price of $15 suddenly doesn’t seem outrageous. Store the pollen in an air-tight container in a cool dark place. For maximum flavor, use within a year of collection.

For more on fennel and many other market farm crops, read Pam Dawling's book, Sustainable Market Farming.

Copyright Growing For Market Magazine. All rights reserved. No portion of this article may be copied in any manner for use other than by the subscriber without permission from the publisher. 

How to Grow Fennel Plants

Fennel is a beautiful herb to have in the garden. Feathery and fern-like, it adds both color and texture to your plantings. It also boasts a strong, licorice-like flavor. Fennel is a tender perennial, which means the plant may make it through the winter in warm areas, but is sensitive to cold. Most gardeners grow fennel as an annual.

Fennel is a beautiful herb to have in the garden. Feathery and fern-like, it adds both color and texture to your plantings. It also boasts a strong, licorice-like flavor. Fennel is a tender perennial, which means the plant may make it through the winter in warm areas, but is sensitive to cold. Most gardeners grow fennel as an annual. Be sure to look for vigorous young fennel plants from Bonnie Plants®, the company that has been helping home gardeners succeed for over a century.

Some varieties of fennel are grown for their leaves, and others for their bulbs.

Quick Guide to Growing Fennel

Soil, Planting, and Care

Fennel prefers soil that is fertile and drains well. Before planting, enrich your existing soil by mixing in compost or Miracle-Gro® Performance Organics®All Purpose In-Ground Soil. If growing in pots, fill them with Miracle-Gro® Performance Organics® All Purpose Container Mix. Both Miracle-Gro products are enriched with aged compost and provide just the right organic nutrition to get plants off to a strong start. Fennel is a sun-loving plant, so plant it where it will receive at least 6 hours of direct sun.

Plant fennel after the last spring frost. This plant can tolerate light frosts, but needs protection when young. Use a frost cloth to cover. When planting, space fennel seedlings from 4 to 12 inches apart, depending on variety. (Check the plant tag for more information.)

Be sure to keep soil consistently moist. Water regularly, giving plants at least an inch of water per week (more in hot weather). Stick your finger into the soil to check moisture; if the top inch is dry, it's time to water.

For best results and super-strong growth, you'll want to build on the nutritional foundation provided by starting with great soil. Regularly throughout the growing season, give your fennel and other plants (as well as the beneficial microbes in the soil) a boost of nutrition, once a week, with a water soluble plant food like Miracle-Gro® Performance Organics® Edibles Plant Nutrition. Continue to feed every 1 to 2 weeks, following label directions.

Once blooms begin to appear, you can either pinch them to prevent the plant from going to seed, or just go ahead and let it flower, to attract beneficial insects

Troubleshooting

The main pest that seems to bother fennel is the parsleyworm, which looks like a green caterpillar with black and yellow bands. Check leaves regularly, and hand-pick worms as soon as you see them, to prevent them from eating the foliage. Or consider leaving them be, if you don't mind sharing your harvest. Parsleyworms turn into black swallowtail butterflies, which are good pollinators.

Harvest and Storage

You can harvest fennel leaves anytime during the growing season – the more you trim it, the bushier it will become, leading to more and bigger harvests for you. Be sure not to trim more than a third of the plant when you harvest. Some types of fennel also produce bulbs, which can be harvested once they measure several inches across. Leaves can be kept on the counter with cut stems in a glass with water. Unwashed bulbs can be kept in the refrigerator for 3 to 5 days.

Uses

Leaves and seeds have a sweet anise flavor, somewhat like licorice. Use leaves in salads, coleslaw, soups, and stews. Bulbs can be sliced for use in salads and side dishes, or roasted to mellow the strong flavor. Fennel flowers are edible, and make wonderful garnishes for fish, meat, potato, and tomato dishes. Fennel stems also look wonderful in fresh bouquets.

Fennel makes an eye-catching backdrop to lower growing herbs in an herb garden.

Fennel Growing Fennel Herb Garden Herb Gardening Herbs How-To Grow Fennel

Fennel.

How to cultivate a Florentine delicacy

There are several types of fennel:

Foeniculum vulgare subsp. piperitum (bitter fennel), Foeniculum vulgare subsp. vulgare var. dulce (sweet fennel) and Foeniculum vulgare subsp. vulgare var. azoricum (Florentine, vegetable fennel)

Vegetable forms of fennel differ from each other in the shape and color of the rosette of leaves, but most importantly - in the shape and size of the sprout. There are varieties with flat or round heads. Plants grow slowly during the initial period of growth. Before stemming, their height reaches 40-60 cm.
To successfully grow fennel, you must meet the requirements for heat, light, moisture, soil, nutrition.

Growing Conditions for Fennel

Fennel prefers areas with long warm and humid summers and mild winters. It grows well on fertile soils, rich in lime, of medium and heavy mechanical composition, with a pH of 6.5-8. Clay and marshy soils are unsuitable for fennel. It responds positively to the introduction of compost and fertilizers with a high organic content. With a lack of nutrients, vegetable fennel forms small heads of cabbage. nine0007

Vegetable fennel develops best with a short day and low air temperature. In the conditions of a long day and with a lack of moisture in the soil, vegetable fennel forms flower-bearing shoots in the first year of cultivation, bypassing the sprout phase at the base of the stem.

Fennel is light-requiring and does not tolerate shading well

The culture must be watered regularly, because in plants that do not receive enough water, or if watering is irregular, the stems crack and the commercial quality of the heads deteriorates. nine0007

Given the growing season, fennel cultivation requires 200-350 mm of natural rainfall or irrigation moisture, depending on the type of soil and its water supply. Dry air can also prevent the full development of sprouts. In small areas, drip irrigation is used to maintain soil moisture.
The best predecessors of fennel are row crops (under which high doses of organic fertilizers were applied) or grain crops. You can grow it after cabbage. Fennel also tolerates cultivation in monoculture. nine0007

Fennel can be grown by direct sowing of seeds into the ground or through seedlings

The growing season of vegetable fennel lasts 90-100 days. It can be grown by direct sowing of seeds into the ground or through seedlings. To grow a sufficient number of seedlings on an area of ​​1 ha, 2.5 kg of seeds are needed. For direct sowing in the same area, 8-10 kg of seeds are required.
Since autumn, the area must be plowed up or dug up to the depth of the arable layer. Before sowing in early spring, the soil is loosened or dug up beforehand. nine0007

For an average yield (20 t/ha), the above-ground mass absorbs NPK 58-26-194 kg/ha. Depending on the type of soil and the amount of nutrients in it, 80-120 kg/ha N, 70-100 kg/ha P (P2O5), 120-160 kg/ha K (K2O) are required for fertilizer. Phosphorus-potassium fertilizers are used as the main ones.

On sandy soils, nitrogen losses are more significant (40-70 kg/ha), with frequent irrigation, potassium can be leached (up to 10%).
To reduce the burden on the environment, nitrogen fertilizers can be applied in several steps. On moderately heavy soils, they can be given in one go. On neutral or slightly alkaline, ammonium nitrate is replaced with ammonium sulfate. nine0007

Sowing fennel, care and feeding

Seeds begin to germinate at 6 °C, the optimum air temperature for plant growth and development is 15-20 °C. Shoots appear in 12-14 days. In the marketable phase, plants tolerate frosts. Vegetable fennel can be sown in open ground when the danger of a strong drop in temperature (down to -2 ° C) has passed.

Care must be taken in doing so, as early crops are more likely to bloom. Fennel vegetable is sensitive not only to the length of daylight hours, but also to a sudden change in temperature. Therefore, if possible, it is better to sow by direct sowing, and not through seedlings, in order to reduce the likelihood of transition to stemming. nine0007

Seeds usually germinate in 7-10 days. To speed up germination, before sowing, they are soaked for 3 hours in warm water, then dried. To enhance germination energy and germination, seeds can be treated with growth stimulants (Zircon, Epin-extra, Epin, Albit).
In the southern regions, vegetable fennel is sown every 3-4 weeks for conveyor cultivation of heads of cabbage.

Last sowing date should be 90-110 days before the first autumn frosts

In northern latitudes, vegetable fennel is sown during the summer solstice. If sowing is carried out in mid-June, the crop is harvested in mid-October. Cabbage sprouts can survive one or two frosts, so you can harvest when cold weather sets in.

The classical sowing rate of fennel seeds is 0.5-1.2 g/m2

The sowing method is in rows with a row spacing of 60-70 cm. - mi in the tape - 20-25 cm. 5-7 days after sowing, harrowing is carried out in order to control weeds. Shoots appear in 20-25 days. When the plants reach a height of 15-20 cm, they must be thinned out. nine0007

According to foreign sources, in the southern regions, vegetable fennel can be sown by direct sowing to a depth of 0.6-1.3 cm with a row spacing of 107 cm. There are 2 lines of seeds on one bed, the distance in a row between seeds is 15 cm. With direct sowing the recommended plant density is 13 pcs/m2. A denser or weaker standing density can provoke stemming in varieties that are sensitive to day length.

According to other sources, the sowing depth of seeds should be 0.6 cm, the distance between seeds in a row should be 10-15 or 15-30 cm, and between rows should be 46 cm.
Sometimes 3 seeds are sown together in one place, leaving 30 cm between each three seeds in a row, and then thinned out, leaving the strongest seedling.

If the soil is dry at the time of sowing, the furrows must first be well watered. After sowing, the seeds are mulched with a soil layer 0.2-1.3 cm thick. Vegetable varieties of fennel are thinned out at a distance of 15 cm between plants in a row. After this, the plants can be lightly hilled. According to data from foreign literature, at the beginning of the formation of heads of cabbage, plants are thinned out at a distance of 20-30 cm in a row from each other. nine0007

When the sprouts have reached the size of a hen's egg, it is necessary to spud up the rows, lightly powdering the soil around the sprout to bleach it.

To make the sprouts more tender and sweeter in taste, as well as to prevent the growth of weeds and maintain coolness and moisture in the upper soil layer, it is necessary to mulch the soil with straw or hay

per season) and weeding in a row. On light soils with a lack of moisture, watering is necessary. nine0007

When growing vegetable varieties, it is necessary to feed the plants 1 time during the growing season. Top dressing is carried out when 3-4 pairs of true leaves are formed: 10-12 g/m2 of ammonium nitrate, 20-25 g/m2 of superphosphate and 10-12 g/m2 of potassium salt.

Fertilizers are applied in the middle of the row spacing to a depth of 10-12 cm. To obtain more tender and bleached heads of cabbage, at the first signs of thickening of the stem, the plants are lightly spudded.

How to harvest and store fennel

Commercial sprouts of class I should weigh 250-350 g. It takes about 3 months to obtain full fennel sprouts. Heads of vegetable varieties are harvested in late autumn when they reach a diameter of 8-10 cm, when they become hard to the touch. nine0007

They are cut at the root and all leaves are removed at a height of 15-20 cm, otherwise there is a danger of wilting. For cutting, it is better to use a sharp knife or secateurs. The sprout is cut just above the tap root, right at the soil line. The leaves are cut above the head of cabbage at a height of 2. 5-5 cm to prepare for sale or storage.
After harvesting, they are washed and packed 20 sprouts in 1 carton. To meet standards, at least 90% of fennel sprouts must be free from insects, worms, mold, rot and other defects that affect product quality. They can also be refrigerated and packed in plastic bags. The shelf life in them is up to 5 days, without packaging in the refrigerator - up to 1 week, or 2-3 months in a cold and humid place. The best storage conditions are 0 °C and relative humidity 9five%.
The ideal marketable yield of sprouts (without stem and leaf residues) is, depending on the variety, 1.5-2.5 kg/m2.

Fresh fennel greens are rich in vitamins
(B9 - Folic acid, C - Ascorbic acid, vitamins A, pp, B5, B6, B2), macro-
and microelements. Of the macronutrients, there are potassium, sodium, phosphorus, calcium, magnesium. Of the trace elements - manganese, copper, iron, selenium, zinc.

Fennel seeds contain 0. 79% essential oil, which has a strong spicy aroma and taste, 5.82% fatty oil and the total amount of phenolic compounds - 1.17 mg/g dry weight. the main components of the essential oil are anethole (50-60%) and fenchone (15-20%).
Raw fennel sprouts contain carbohydrates, dietary fiber, protein, vitamin B complex, vitamin C and minerals.

Fennel through seedlings

To obtain better and earlier yields of vegetable varieties, the seedling method of cultivation is used. For this, plants are sown in boxes or cassettes in a warm room 4-6 weeks before the start of the frost-free period. nine0007

Growing fennel through seedlings is useful in areas with a short spring or a short warm period in general (northern latitudes)

Fennel does not tolerate root disturbances. 3 seeds are sown in the cell of the cassette to a depth of 0.6 cm. When the seeds germinate, the strongest seedling is left in the cell.

Plants are transplanted into open ground from mid-spring to the end of summer, when seedlings are 4-6 weeks old and 8-10 cm high. Row spacing 46 cm wide, between plants in a row - 15-30 cm. It is advisable not to thicken plantings. so as not to provoke the transition to stalking. With the classical planting scheme, when the seedlings reach the age of 45-60 days, they are planted in open ground when there is no threat of return frosts (end of May - beginning of June). The method of planting seedlings is 40 × 20 cm or 40 × 30 cm. nine0007

Florentine sweet fennel leaves and head are used raw and cooked. The cabbage can be fried, stewed, grilled. It is a very good source of dietary fiber, as well as calcium, potassium and fiber, and lowers blood cholesterol levels.

Fennel roots are edible. The taste is reminiscent of root parsley. They are added to vegetable stew. The leaves are crushed and added to soups and as a seasoning for fish. Stems and young umbrellas are preserved separately, added when pickling cucumbers and other vegetables. The stems are dried or frozen. Young leaves of vegetable fennel can be added to a salad for children. nine0052

Aleksey Baranov, Candidate of Biological Sciences, Gavrish Company

Growth and development of common fennel plants

Agriculture

Introduction

Common fennel ( Foeniculum vulgare Mill . ) is a culture with a wide range of uses and an inexhaustible potential for useful properties. The use of fennel is multifaceted: medicine, cooking, various industries (food, pharmaceutical, perfumery and cosmetics), as well as veterinary medicine and animal husbandry. Taking into account the diverse properties, fennel can be attributed to medicinal, essential oil, spicy, vegetable, melliferous and ornamental plants [1-4].

In recent years, numerous studies of new possibilities for the use of fennel have been carried out in the world, and ideas about traditional, long-known properties have been significantly expanded [5-11]. Unfortunately, in modern research, issues of improving cultivation technology, studying the botanical-biological, biometric, and phenological characteristics of the culture take a secondary place. nine0007

Information on the growth and development of fennel is rather contradictory, which may be due to the influence of soil and climatic conditions of various growing zones, the level of agricultural technology achieved, and varietal characteristics.

Common fennel, common in culture, is a perennial hemicryptophyte. At the beginning of an unfavorable period, the shoots of the plant die off, the underground organs hibernate with renewal buds. In the regions of traditional cultivation, fennel is grown as an annual or biennial crop [12, 13]. nine0007

The duration of the vegetation period of plants varies in the range from 130 to 200 or more days, depending on the geographical origin of the variety and the ecological conditions of the zone. When fennel is cultivated as an annual crop in areas with an insufficiently long summer period, the seeds often do not ripen [2].

Seedlings appear 10–20 [14] or 20–30 days after sowing [15]. Seedlings and initial stages of growth and development of plants are unfriendly, extended in time [16, 17]. Flowering is uneven and lasts from July to August [3, 18]. In California, on Santa Cruz Island, fennel blooms from February to September [19]. The fruits ripen in September-October [3, 14, 20].

In Germany, in the first year of cultivation, fennel blooms from July to October, in the second year - from June. With an annual crop, the seeds ripen in October-November, with a two-year crop, from mid-September [15]. Ripe fruits crumble, give intensive self-seeding [4].

An important scientific and practical value for the successful cultivation of common fennel in the zone of the southern Steppe of Ukraine is the study of the main patterns of growth and development of plants, taking into account the varietal characteristics of the culture, the soil and climatic conditions of the zone, and technological methods. These studies will make it possible to correctly design agrocenoses for various intended uses, predict and regulate the duration of the main phases of plant development, the yield of green mass, melliferous, seed productivity of crops, plan and carry out harvesting of greens, seeds, raw materials (fruits and aboveground mass) for production in optimal terms. essential oil, perform selection work. nine0007

Materials and methods

The experiments were carried out in 2014-2016 in the zone of the southern Steppe of Ukraine on the fields of the farm "Fantasy" B.-Aleksandrovsky district of the Kherson region in compliance with generally accepted methods and recommendations (Fig. 1).

Rice. 1. Sowing fennel ordinary in the zone of the southern Steppe of Ukraine

On the experimental plot, the soil is dark chestnut, slightly solonetsous, medium loamy, typical for the zone. The arable layer of the soil contains humus - 2.28%, nitrates - 26, mobile phosphorus - 34, exchangeable potassium - 250 mg / kg of soil, pH of the water extract - 7. 0-7.2. During the years of research, the weather conditions differed in temperature regime, amount and distribution of precipitation, but in general were typical for the southern Steppe zone of Ukraine. nine0007

The predecessor of fennel was winter wheat. Under the main tillage, 60 kg of AI/ha of ammonium sulfate was applied. The object of study is the Oksamyt Kryma fennel variety. The culture was sown early (the third decade of March), the seeding rate was 5 kg/ha, the row spacing was 45 cm, the seed placement depth was 3-4 cm, and the plant density was 600 thousand/ha. The fennel seeds were harvested when the fruits ripened on the central umbel and umbels of the first order.

The objectives of the research included determining the timing and characteristics of the passage of the developmental phases of common fennel, the duration and structure of the growing season, morphological and biometric parameters of plants in the main developmental phases. To solve the tasks set, phenological observations and biometric measurements were carried out according to generally accepted methods [21, 22]. nine0007

Results and discussion

Common fennel is a perennial polycarpic plant with a perennial root and annual (monocyclic) shoots, the development cycle of which is completed within one growing season. Shoots die off every year, successively replacing each other. Depending on the soil and climatic conditions of the zone, the availability of thermal resources, and the characteristics of the winter period, fennel is cultivated as an annual or biennial crop. nine0007

In the arid conditions of the southern Steppe of Ukraine, fennel seeds are formed during one growing season, so the crop is grown as an annual [23]. The weather conditions of the winter period are characterized by frequent rains, the periodic onset of a thaw followed by cooling, the formation of an ice crust, a small and unstable snow cover, which negatively affects the physiological state of plants. Cultivation of fennel as a biennial crop in the south of Ukraine is associated with the risk of plant death and sparseness of crops under the influence of a complex of unfavorable factors of the winter period. nine0007

The research results show that in 2014-2016. fennel seedlings were obtained 18-24 days after sowing. The length of the growing season was 132-135 days.

The phase of the first pair of true leaves was recorded 15-16 days after germination, the phase of a rosette of 5-6 leaves - after 34-35 days, the formation of the first internodes of the central stem - after 43-45 days, the appearance of plants with formed vegetative organs (stem and leaves) - after 59-61 days. Thus, the pregenerative period of fennel development from germination to stemming lasted 59–61 days (Fig. 2).

Rice. 2. Length of interphase and vegetation periods of fennel plants in 2014-2016, days

The duration of the interphase period stemming-flowering was 16-21 days, flowering-fruit formation - 17 days, fruit formation-ripeness - 37-39 days. The total duration of the generative period of development was within 72-76 days. nine0007

The length of the interphase and vegetation periods of fennel plants as a genetically determined characteristic of the culture and variety varied under the influence of weather conditions during the years of research in a small range.

On average for 2014-2016, the pregenerative period of development of fennel plants in the structure of the growing season occupied 44%, the generative period - 56%. The length of individual interphase periods as a percentage of the total duration of the growing season varied from 11 to 29% (Fig. 3).

Rice. 3. The structure of the growing season of fennel vulgaris

During the early spring sowing of common fennel in the third decade of March, seedlings were observed in the second decade of April (Fig. 4). A significant duration of the period from sowing to the germination phase is due to the morphobiological characteristics of the seeds: a dense seed coat, low germination and germination energy. According to the results of laboratory studies, the energy of seed germination was 30-40%, laboratory germination - 61-83%. nine0007

Rice. 4. Formation of the leaf apparatus of fennel plants

The cotyledon leaves of fennel are simple, poorly differentiated, the leaf blade is entire, elongated-lanceolate in shape, green in color without a characteristic bluish bloom. Cotyledon leaves differed from true leaves in their shape. They persisted in plants until the rosette of leaves phase. The root of seedlings is white, thin.

The first pair of true leaves formed in the first decade of May, the second pair - in the middle of May. The intensity of leaf formation was, on average, one leaf per 7 days. During this period, plants were characterized by slow growth and development. nine0007

The first true leaves appeared one at a time from a bud located between the cotyledon leaves. In shape, they are heart-shaped, pinnately dissected, small, the color is green without a bluish coating. The first true leaves were distinguished by weak differentiation and imperfect dissection of the lamina. Each subsequent leaf acquired more and more characteristics characteristic of fennel. The formation of lateral roots was observed during the period of the appearance of the first true leaf.

At the initial stages of growth and development, common fennel can be oppressed by weeds, as it is characterized by low competitiveness in relation to them. This is due to the significant duration of the period from sowing the crop to the emergence of seedlings, the slow formation of two pairs of true leaves. The first 1.5-2 months after sowing is a herbocritical period for common fennel plants, therefore careful soil preparation, field cleanliness from weeds are especially important for successful crop cultivation. nine0007

Intensive growth and development of fennel plants were observed from the third decade of May - in the rosette phase of 5-6 leaves. During this period, the leaves acquired typical morphological features for the culture: they are ovate-triangular or elongated-oval in shape, glabrous, repeatedly pinnatisected into long narrow thread-like lobes, dark green with a bluish bloom. Leaf petioles are zholobovidnye, the base of the plant is thickened up to 1 cm.

In the first ten days of June, in the phase of 7-8 leaves, opening of leaf sheaths, the formation of several leaf primordia on the plant, and the formation of two or three internodes of the central stem were noted. nine0007

In the second decade of June, during the stemming phase, the plants formed the central stem and leaf apparatus (Fig. 5).

Rice. 5. Planting phase of fennel

The fennel stem is annual, erect, strongly branched, has spirally arranged shoots of the first, second and subsequent orders, which emerge from the leaf sheaths. The stem is glabrous, dark green with a bluish bloom, with well-defined nodes and hollow internodes, rounded slightly ribbed in cross section. The number of internodes is 6-7, the diameter of the stem at the base is 0.9-1.1 cm.

The leaves are alternate. The base of the petiole is expanded into the sheath, covering the stem, the fennel nodes are full (closed). The sheaths protect the stem and axillary buds from which the side shoots are formed. The sheath of the upper leaf on the central stem protects the apical bud from which the inflorescence develops.

The leaves within the plant differed significantly. The leaves of the lower tier (rosette) are larger, complex, strongly dissected, petiolate, the sheaths cover the stem. The leaves of the middle and especially the upper tiers are smaller, less dissected, sessile or almost sessile, the leaf blade passes into the leaf sheath. The apical leaves are small, dissected into narrow lobes, of which there can be only three. Thus, towards the top of the stem, the leaves were reduced and simplified. nine0007

In the stalking phase, the number of leaves per plant was, on average, 20 pieces, of which 5-6 leaves are small apical.

Fennel root is taproot, fleshy, thickened (up to 1 cm in diameter), fusiform, branched above, yellowish-white.

The generative period of fennel development included the formation of inflorescences and the gradual qualitative transformation of their structural elements: buds, flowers, ovaries, fruits (Fig. 6).

The flowers are small, yellow, actinomorphic (regular), bisexual, five-petalled, on long stalks. The calyx is inconspicuous or absent. Corolla not fused, about 3 mm in diameter. Petals are rounded or broadly ovate, with a notch at the top, five stamens alternate with petals. Pistil with lower, ribbed, bilocular ovary and one ovule in each nest.

The flowers are collected in inflorescences of complex umbrellas - apical, flat, unequal, 6-11 cm in diameter, consisting of 5-12 simple umbrellas. nine0007

The fennel fruit is an oblong-oval, concave, slightly tapering towards both ends, grayish-green or grayish-brown two-seeded seedling with longitudinal, lighter ribs.

Rice. 6. Generative period of development of fennel ordinary

The fruit consists of two seeds. When ripe, the fruits arbitrarily or as a result of mechanical action break up into two single seeds, easily crumble. nine0007

The mass of 1000 seeds, on average, was equal to 5.42 g. The structural composition of the seeds is represented by one- and two-seedlings in a weight ratio of 1. 5:1. Seedlings were characterized by higher weight, laboratory germination, and germination vigor compared to seeds in whole fruits [24].

Flowering of common fennel was observed in the first decade of July, fruiting - in the third decade of July, the ripeness phase - in the third decade of August-first decade of September.

The number of shoots of the first order during the period of generative development was 9-10 pieces. per plant, each of them has, on average, two shoots of the second order. The central stem and each side shoot ended in a generative organ. The formation of a system of lateral shoots is an important reserve for regulating the productivity of crops with different plant density, an indicator of the ability of plants to adapt to cultivation conditions.

The generative development of common fennel was characterized by a non-simultaneous onset and, as a result, the passage of phenological phases within the inflorescence, plant. nine0007

The blooming of flowers in a simple umbrella and simple umbrellas in a complex one took place centripetally. The inflorescences on the plant developed basipetally, from the top to the side shoots.

The central umbel opened during the first decade after emerging from the leaf sheath. During the next 5-6 days, a gradual yellowing of the buds from the periphery to the center of the inflorescence was noted, which partially coincided with flowering.

On the 13-14th day after the appearance of the inflorescence, the flowering phase began, which lasted 6-8 days. The formation of the ovary was observed on the 16-18th day after the appearance of the inflorescence and took place in 14-16 days. The beginning of fruit formation was noted a month after the appearance of the inflorescence, the duration of the phase was four decades. nine0007

A separate bud acquired a characteristic yellow color in 3-4 days, the flowering of one flower lasted 2-4 days. The ovary within 7-10 days acquired a grayish-green color and increased in size, after another 3-5 days barely noticeable ribs appeared on the surface. The formation and maturation of an individual fetus lasted 35-40 days.

The interval between the appearance of the inflorescence on the central stem and side shoots of the first order was one decade, on the shoots of the second order - two decades. The central umbel bloomed first and later formed the fruits, then the umbrellas of the next orders. nine0007

From the beginning of the fruit formation phase on the plant, all stages of the development of generative organs were revealed: the beginnings of inflorescences, open green and flowering umbels, umbels with ovaries and fruits of varying degrees of ripeness. The number of generative organs was, on average, 30 pcs. on a plant.

Given the need for mechanized harvesting in a short time, the central umbrella and the two upper umbrellas of the first order were of value. This is due to the non-simultaneous development of inflorescences and the formation of fruits. Delays in harvesting in anticipation of the maturation of lagging, less productive umbels of the lower orders and tiers of the plant can lead to shedding and significant losses of the most valuable fruits of the three upper inflorescences. nine0007

The height of fennel plants, on average over the years of research, in the seedling phase was 3.2 cm, in the phase of the first pair of true leaves - 8.7 cm, in the rosette phase of 5-6 leaves - 22.6 cm. Intensive linear plant growth fennel was observed during the formation and growth of the central stem. In the stalking phase, the plants reached a height of 65.9 cm, in the flowering phase - 104.3 cm, after which the linear growth stopped (Fig. 7).

Rice. Fig. 7. Dynamics of changes in the height of fennel plants by development phases, cm nine0007

The average daily increase in plant height was 1.3 cm per day. The intensity of linear growth changed significantly during the vegetative period of the culture and reached the highest values ​​in the interphase periods rosette of leaves - stalking - 1.7 and stalking - flowering - 2.0 cm per day.

The leaf surface area of ​​common fennel, on average for 2014-2016, was 44 in the germination phase, the first pair of true leaves - 113 m 2 / ha, rosettes of leaves - 4. 1 thousand m 2 / ha. This indicator reached its maximum value in the stalking phase - 29.8 thousand m 2 / ha (Fig. 8).

Subsequently, gradual drying and death of the leaves of the lower tier was observed. The leaf surface area of ​​common fennel in the flowering phase was 24.3 thousand m 2 / ha, in the phases of fruit formation and ripeness it significantly decreased - to 17.4 and 2.9 thousand m 2 / ha, respectively.

In the interphase period shoots - rosette of leaves formed 14% of the area of ​​the assimilation apparatus, rosette of leaves - stalking - 86%. The ratio of the length of these interphase periods is 1.3:1. nine0007

Rice. 8. Leaf surface area of ​​common fennel by development phases, thousand m 2 /ha

The average daily increase in leaf surface area was 0.5, the range of its variation was 0.1-1.0 thousand m 2 /ha per day. The minimum value of this indicator was recorded in the period from the germination phase to the rosette of leaves, the maximum - in the interphase period of the rosette of leaves - stalking.

The average daily increase in dry matter of fennel was 4.9g from 1 m 2 sowing per day. Based on the analysis of the dynamics of fennel dry matter by development phases, it can be concluded that there are significant changes in the intensity of its accumulation during the growing season of the crop.

On average, over the years of research, the value of the dry aboveground mass of fennel in the germination phase was 0.002 t/ha, in the phase of the first pair of true leaves - 0.008 t/ha, the average daily gain was the smallest during the growing season - 0.04 g/m 2 (Fig. . nine).

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Rice. 9. Dynamics of formation of dry matter of fennel ordinary by phases of development, t/ha

The yield of dry matter in the leaf rosette phase was 0.24 t/ha, the average daily gain increased to 1.2 g/m 2 . In the period from germination to the rosette of leaves, which lasted 34 days, 4% of dry matter was formed.

Intensive accumulation of the dry above-ground mass of fennel ordinary was observed from the phase of the rosette of leaves to the flowering of the culture. In the interphase period rosette of leaves - stalking formed 3.39t/ha, or 51% of dry matter, stem-flowering - 2.24 t/ha, or 34%, average daily gains reached the highest values ​​during the growing season - 13.0 and 11.8 g/m 2 , respectively. The yield of dry matter in the stalking phase was 3.63, flowering - 5.87 t/ha.

In the interphase period flowering-fruit formation, a decrease in the intensity of accumulation of dry matter to 3.2, fruit formation-ripeness - up to 0.5 g/m 2 per day was observed. The share of dry above-ground mass formed during these periods in its total structure was 8 and 3%, respectively. The yield of dry matter in the phase of fruit formation reached 6.41, ripeness - 6.59t/ha

Terminals

In the arid conditions of the southern Steppe of Ukraine, common fennel is cultivated for seeds as an annual crop.

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