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How to plant zinnia flowers


How to Plant and Grow Zinnias

From watering tips to when to deadhead, we asked two gardening experts to share their advice.

Caroline Biggs, Freelance Writer portrait

By Caroline Biggs October 08, 2020

If you're a fan of colorful, low-maintenance flowers, then you shoulder consider planting zinnias in your garden. "Zinnias are universal symbols of summertime that bloom from mid-summer until the first frost, in crisp, vibrant colors such as pink, red, orange, yellow, green, and white," says Venelin Dimitrov of Burpee. "The flowers bloom in a range of shapes, including quilled, dahlia-type, single, semi-double, and double flowers. Plus, they are excellent flowers for new gardeners and children to grow, as the seeds are large and easy to handle, and the flowers often attract many species of butterflies."

zinnias in a garden

Credit: Getty / Chuanchai Pundej / EyeEm

Along with being beautiful and easy to grow, zinnias are also heat- and drought-tolerant. "They are great for hot summer weather and gardeners in warmer climates," explains Dr. Gladys Mbofung-Curtis, a garden expert at Garden Safe. "Zinnias are one of the easiest flowers to grow because seeds require only basic garden preparation to sprout and the plants flower in just a few weeks; they can flourish with very little fertilizer and still produce flowers."

Plant zinnias in full sun.

Zinnias thrive in full sunlight and should be planted at the beginning of the warm weather season. "They are short-day plants that flower when the day length is less than 11 hours, therefore they are perfect for early spring planting when the nights are longer," Mbofung-Curtis explains. "Zinnias grow and flourish well in full sunlight in cooler climates, but in warmer climates, occasional afternoon shade may help relieve the plants from the excessive heat."

Seed zinnias in moist soil.

In warm climates, zinnias should be seeded directly into the soil after any frost has passed, says Mbofung-Curtis; in cooler climates, seeds can be started indoors in germination trays. "Whether seeding directly in beds or germination trays, zinnia seeds should be sown to a depth of a quarter of an inch into deep, loamy soil," she says. "The distance between seeds or seedlings in the beds should be about six inches apart for good airflow and rows should be spaced 12 inches apart."

Water carefully.

Even though zinnias can tolerate short periods of drought, Mbofung-Curtis says they'll grow best in moist soil. "Water plants about three times a week so that the soil stays moist to about six to eight inches deep," she advises. "Overwatering and continuous wet conditions can take a great toll, since high humidity can lead to development of powdery mildew, leaf spots, and rot, so water at the base of the plants." For potted plants, she recommends only watering them when the soil feels dry. "Avoid splashing the leaves as this may splatter spores of the fungus from the ground to the leaves."

Mulch makes a difference.

While zinnias can grow well in average soils, Mbofung-Curtis says they'll perform better with the help of compost, fertilizer, or mulch. "Once zinnias are established, mulching with a two-inch layer of straw or bark will help preserve soil moisture and prevent weed growth. In addition, a light fertilizer may be applied at the seedling stage. At flowering, side dressing with an organic 5-5-5 fertilizer will produce numerous and bigger blossoms. Zinnia seeds can also be sowed directly into one to two inches of organic mulch that will provide nutrients throughout the season as the mulch breaks down to form compost."

Prune frequently.

A little pruning can go a long way when growing zinnias in your garden. "When zinnias have grown to several inches, prune frequently to encourage more branches for flower head growth," Mbofung-Curtis says. "Rather than allowing flowers to be spent on the plants before deadheading, cut the mature flowers for use in bouquets to encourage blossoming throughout the season. Otherwise, just pinch spent blossoms off. However you maintain them, your zinnias will continue blooming to produce more and more flowers. "

How to Plant and Care for Zinnia Flowers

Zinnias are a gift for gardeners in hot climates, where they thrive and grow easily. They are fast-growing, warm-season annual flowers that bloom with abandon, requiring only minimal care. Zinnias come in bold, hot-palette colors, with new ones introduced yearly, including some cool whites. Varieties come short, spreading, and tall (up to 4 feet tall).

Zinnia elegans has lance-shaped, rough leaves, but other varieties have broader, less scratchy leaves. Flowers are rounded and may be daisy-like, double, cactus-flowered, or a formal-looking dahlia-type. Zinnias flower all summer and often into fall, lasting in the garden from two to five months. Zinnias are most robust during the hot summer and the warmest spring and autumn months. Zinnias don't need to be deadheaded, but your plants may have a longer bloom period if you do.

As the weather warms up in the spring, start planning a day when you can plant your zinnias. Zinnias are one of the few plants that are true annuals, meaning they do not come back every year. You will need to plant new seeds or starts every growing season. They can withstand some of the worst growing conditions but make sure to give zinnias full sun.

​The Spruce / Letícia Almeida The Spruce / Letícia Almeida The Spruce / Letícia Almeida  The Spruce / Letícia Almeida 
Common Name Zinnia 
Botanical Name Zinnia elegans
Plant Type Annual
Mature Size  1-4 ft. tall, 6-18 in. wide
Sun Exposure Full
Soil Type Well-draining
Soil pH Neutral
Bloom Time Spring, summer, fall
Flower Color Pink, purple, yellow, orange, white, red, green
Hardiness Zones 3-10 (USDA)
Native Area South America, North America

Zinnia Care

Zinnias, unlike many plants labeled as annuals that are perennial in the warmest hardiness zones, are annuals everywhere.

Zinnia plants can take a few weeks to become established, but once it warms up, expect them to bloom from late spring through fall. The vibrant, tropical colors of zinnias work well in a hot border, picking up the hues of other reds and oranges. They are also nice for adding dramatic color to a container.

The tall Zinnia elegans is still a favorite for the back of the border, but new varieties, like the 'Thumbelina' series, grow only about 6-inches tall and make great choices as edging plants or in containers.

Planting and Soil

Zinnias are best planted in the spring. Zinnias are not picky about their soil but need their space. So, if you're planting a smaller variety of zinnia seeds, leave at least 6 inches between plants. Larger types of zinnias need at least 12 to 18 inches between plants for proper air circulation and disease prevention.

When sowing zinnia seeds, you can put two or three seeds in each hole to increase your chances of a seed germinating in that spot. However, if two or three plants sprout, remove the weakest seedlings once they've grown two to three inches. Keep only the most robust one.

The soil you use must be well-draining. If your soil is poor, you can add some compost to give the plants a boost, but zinnias will grow in even bad soil. Zinnia roots can't tolerate damp soil. Excess moisture can lead to the flowers getting a fungal infection, like powdery mildew. It helps to have a soil pH in the neutral range, but it's not mandatory.

Light

Plant zinnias in a spot with full sun. You will get the most prolific blooms in a sunny spot, and it will help to keep the leaves dry and thwart powdery mildew before it starts.

Water

Zinnias are very drought tolerant and don't usually need any supplemental watering.

Temperature and Humidity

It doesn't matter how hot the summer gets; zinnia plants just keep on blooming.

Fertilizer

Zinnias are easy-going plants, needing only occasional feeding with a well-balanced fertilizer. For the amount to use, follow product label instructions.

Types of Zinnias

Some varieties are spreading, dwarf zinnias only grow about 6 to 8-inches tall, and the classic zinnia elegans can reach 4 feet tall. Here are some types to try:

Pruning

Zinnias make great cut flowers for bouquets. The more you pick, the more they bloom. Or you can deadhead zinnias for a longer blooming period, but it's unnecessary. They may pause flowering for a while, but they'll start up again.

Propagating Zinnias

There are several ways to propagate zinnias: by division, using already established plants, or with cuttings.

How to Grow Zinnias From Seed

This plant is extremely easy to start from zinnia seeds. You can direct sow as soon as the soil has warmed, and there is no chance of frost. Sow seeds about 1/4 inch deep. You can also start seed indoors, about four to six weeks before your last frost date. Every garden center has zinnia seedlings for sale if you don't have seeds saved; however, you will have less choice of varieties.

Potting and Repotting Zinnias

You can start all zinnia seeds in small pots, but only shorter zinnia varieties can remain in pots. Tall zinnias do not do well in pots. If you must stick to a container garden, consider using hybrid bedding zinnias that tend to have a short, spreading growth habit.

Overwintering

Zinnias are annuals. The only way to keep them going through the winter is to dig them up and bring them inside.

Common Pests and Diseases

It is rare for zinnias to be bothered by insects and most four-footed animals show no interest in them.

Some varieties can be very prone to powdery mildew. It's ugly, but it's unlikely to harm your plants. To cure, clip back the parts of the plant that are affected. Then, apply a fungicide with neem oil, potassium bicarbonate, copper, or sulfur.

​The Spruce / Letícia Almeida

Article Sources

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Disease Resistant Annuals and Perennials in the Landscape. Perdue University Extension.

  2. Zinnia. University of Minnesota Extension

  3. Zinnia Are Colorful Favorites! Featuring Profusion and Zahara Series. University of Tennessee Institute of Agriculture.

  4. Powdery Mildew on Ornamentals. University of California Agriculture and Natural Resources.

Growing zinnia from seeds. How to get lush bushes

Unique flower arrangements with zinnias are quite an exciting sight. Smooth rows of amazing colors of unbending zinnia give the impression of a military bearing. Perhaps that is why the second name of the flower is majors. Marked very accurately. Just tough tin soldiers. Only very bright cheerful and friendly.

tracy ducasse / Flickr.com

And not only friendly, but also quite unpretentious in planting and care.

To grow a worthy flower, you need to know the individual preferences of zinnia and try to stick to them.

So, for example, when planting it is necessary to take into account that this plant loves heat and light. Accordingly, will not suit her, place is somewhere in the shade. Zinnia will not survive even short-term drops in temperature to negative values. This means that it should be planted only when it is known for certain that the frost period has ended.

Zinnia loves watering , but will never put up with waterlogging of the soil. However, as with weak moisture in the root layer. Low moisture reserves in the soil are immediately reflected in flowering - the flowers become smaller and begin to dry out a little bit. Exit? Only uniform and regular watering (without overflow) and zinnia will show itself in full glory. In continuation of the topic of watering, I note that in order to avoid stagnant water, the soil should be provided with good drainage when planting a plant. In general, the soil should be loose and fertile.

It is very good if the soil is filled with organic and mineral fertilizers already in autumn.

Elena Sukhanova / Personal archive

Planting zinnia. You can sow zinnia seeds directly into open ground or grow seedlings first. The second method will allow you to get earlier flowering. Both the first and second cases are simple and do not create problems. Zinnia seeds are quite large, it is pleasant to deal with them.

Before planting, it is necessary to help the seeds: treat them with a growth stimulator, germinate and select with good germination.

If you prefer seedling method, it is better to choose separate containers, and even better - peat cups. Zinnia does not like transplants, so by choosing them, you will make the moment of planting in open ground the least traumatic.

Zinnia is a fast growing flower so don't try to plant seedlings before April. With early sowing, the condition of the seedlings worsens, it stretches and becomes thinner.

Seeds are sown to a depth of 1 cm. It is not necessary to cover and create a greenhouse effect, they will germinate in a week anyway. Seedlings will need watering, a few top dressings, and hardening before planting in the ground. To form a beautiful bush, pinch the top. When the cold leaves, the seedlings can be sent to the flower bed.

Elena Sukhanova / Personal archive

Zinnia is planted in a flower bed at a distance of 30-35 cm from each other, the same distance is given between rows. Planting can be done in different ways. In a row, in a hole, as you like. If you thicken the landing, you can always correct the situation by thinning.

When planting seeds in open ground, it is, of course, difficult to indicate the exact dates. You just need to remember that the seeds germinate for about a week and it is very important that the frost period is over by this time. Otherwise, just cover the landing with a covering material.

In open ground. Of course, most often preference is given to planting seeds immediately in open ground. Planting seedlings, for example, at the end of May, the flowering of zinnia will begin at the end of June, and having planted seeds at the same time, we will see flowering zinnia at the end of July.

Care of growing zinnia involves moderate watering (no overflow), weed removal and loosening.

If you like lush bushy zinnias, pinch the center of the stem. If you prefer tall and slender plants, this technique does not apply. As for top dressing, if zinnia feels great in a flower bed, it does not need to be fed. Only in cases of retardation in growth and development are complex mineral supplements indicated.

Suzie's Farm / Flickr.com

In favor of planting zinnia in your garden is the fact that modern varieties offer a rich range of colors. The size of the inflorescences and the variety of heights are impressive: from 20 cm to 100 cm, i.e. for every taste. Zinnia blooms for more than a month. She proved herself excellently in the cut. A bouquet, with proper care, stands in a vase for a week or more.

In my opinion, with such exceptional qualities, it is worth making a choice in favor of the majors. Do you agree?

Related information

Related discussions

when to plant, growing from seed, planting and care in the open field

Zinnia is a very popular plant grown throughout the former Soviet Union. At home, it is considered a perennial plant. In our country, it dies when the temperature drops below zero. Consider growing a flower from seeds: when and how to plant in open ground.

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