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What does coffee do for plants


How to Use Coffee to Water Plants

By

Colleen Vanderlinden

Colleen Vanderlinden

Colleen Vanderlinden is an organic gardening expert and author of the book "Edible Gardening for the Midwest." She has grown fruits and vegetables for over 12 years and professionally written for 15-plus years. To help move the organic gardening movement forward, she started an organic gardening website, "In the Garden Online," in 2003 and launched the Mouse & Trowel Awards in 2007 to recognize gardening bloggers.

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Updated on 06/07/22

Reviewed by

Mary Marlowe Leverette

Reviewed by Mary Marlowe Leverette

Mary been a Master Gardener for 30+ years and a commercial and residential gardener for 50+ years. She is a former Clemson University Extension Agent. She worked to develop the Riverbanks Botanical Garden that opened in 1995. Mary co-owns Marlowe Farms Apple Orchards.

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Fact checked by

Emily Estep

Fact checked by Emily Estep

Emily Estep is a plant biologist and fact-checker focused on environmental sciences. She received a Bachelor of Arts in Journalism and a Master of Science in Plant Biology from Ohio University. Emily has been a proofreader and editor at a variety of online media outlets over the past decade.

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The Spruce / Danielle Holstein 

Coffee is part of our daily life and a common gardening question is whether it's okay to water plants with leftover coffee or to add coffee grounds to the compost pile.

The answer is yes, in some situations using coffee when gardening is not only acceptable but a good idea. There are some caveats, though. 

Using Leftover Coffee Grounds

The Spruce / Danielle Holstein

Coffee grounds are a good source of nitrogen in your compost pile or when added directly to the soil in the garden. If added in fairly large amounts, they can raise the acidity level of the soil for acid-loving plants such as blueberries, azaleas, and rhododendrons. Coffee grounds sprinkled over the ground around acid-loving plants serve as a mild acid fertilizer for them. And worms seem to love them, either in your garden or outdoor compost pile or in a vermicompost bin.

And coffee grounds are regarded as an effective natural deterrent to garden pests such as slugs, snails, and ants. Rumors of coffee grounds repelling deer may be overstated. Deer are voracious eaters, and a few cups of coffee grounds are unlikely to make much of a difference. Coffee grounds will discourage a mischievous cat from roaming in your garden, but its effectiveness on rabbits and other common garden rodents is unknown.

Tip

If you're not a coffee drinker, don't forget your used tea leaves. They work great as a soil enhancer around acid-loving plants and add nutrients to compost piles.

How to Use Leftover Liquid Coffee

The Spruce / Danielle Holstein 

If you brew coffee by the pot, you may wonder if the cold leftovers can be used to water plants. Or, can the remaining half cup of cold coffee in your mug be poured into that potted pothos plant next to your desk?

The short answer is: maybe. It depends on the plant. Plants that prefer more acidic soil (such as African violets, Impatiens, Norfolk Island pines, Phalaenopsis orchids, and Dieffenbachia) seem to respond well to a weekly watering with coffee. Outdoors, acid-loving plants like azaleas, Rhododendron, Siberian iris, lupine, and any pine trees or shrubs will do fine if periodically watered with cold coffee. Liquid coffee can also be used to water a compost pile that has become too dry. 

If you decide to try watering houseplants with coffee, keep a close eye on your plant. If the foliage starts yellowing or the tips of the leaves start turning brown, it's a sign that the coffee is adding too much acidity to the soil. It's not a bad idea to dilute your coffee with water, especially if you prefer your daily cup of java on the strong side. In some offices, the only "watering" plants received is from emptying leftover coffee into the soil, and they often do quite well. 

One caveat: if you add cream, milk, or sugar to your coffee, don't pour it into your plants. Ditto for flavored coffees. The sugars and fats can not only harm your plants and invite pests but can eventually result in a stinky mess. A plant watered with sweetened or flavored coffee may soon be overrun by fungal gnats or odorous house ants.

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. Grounds in the Garden. Texas A&M University AgriLife Extension.

  2. Acid Soil Problems. Louisiana State University Agricultural Center.

  3. Fungus Gnats Tiny Flies Around Your Houseplants. University of Wisconsin at Madison Department of Entomology.

Coffee Used On Plants - How To Water Plants With Coffee

Home › Gardening How To › Soil, Fixes & Fertilizers

Soil, Fixes & Fertilizers

By: Amy Grant

Image by byryo

Many of us start the day with some sort of coffee pick me up, whether it’s a plain cup of drip or a double macchiato. The question is, will watering plants with coffee give them that same “perk?”

Can You Water Plants with Coffee?

Coffee used as a fertilizer is not exactly a new idea. Many gardeners add coffee grounds to compost piles where it decomposes and mixes with other organic matter to create some fantastic, nourishing soil. Of course, this is done with grounds, not the actual cold cup of coffee sitting here at my desk. So, can you water your plants with coffee proper?

Coffee grounds are about 2 percent nitrogen by volume, nitrogen being an important component for growing plants. Composting grounds introduces microorganisms that break down and release the nitrogen as it raises the temperature of the pile and aids in killing weed seeds and pathogens. Very useful stuff!

Brewed coffee also contains measurable amounts of magnesium and potassium, which are building blocks for plant growth as well. Therefore, it seems a logical conclusion that watering plants with coffee might indeed be very beneficial.

Of course, you wouldn’t want to use the cup sitting in front of you. Most of us add a little cream, flavoring, and sugar (or sugar substitute) to our Joe. While real sugar would not pose a problem to the plants, milk or artificial creamer won’t do your plants any good. Who knows what effect any of the many artificial sweeteners on the market would have on plants? I’m thinking, not good. Be sure to dilute before watering plants with coffee and don’t add anything else to it.

How to Water Plants with Coffee

Now that we have ascertained that we should use diluted coffee for plant fertilizer, how do we do it?

Coffee has a pH of from 5. 2 to 6.9 depending on the variety and preparation. The lower the pH, the more acid; in other words, coffee is pretty acidic. Most plants grow best in slightly acid to neutral pH (5.8 to 7). Tap water is slightly alkaline with a pH greater than 7. Therefore, using diluted coffee for plants can increase the acidity of the soil. Traditional chemical fertilizers, the addition of sulfur, or allowing leaves to decompose on soil surfaces are methods to decrease soil pH levels. Now you have another option.

Allow your plain brewed coffee to cool and then dilute it with the same amount of cool water as coffee. Then simply water acid-loving plants such as:

Water with the diluted coffee just as you would with plain tap water. Don’t use this to water plants that do not like acidic soil.

Don’t water every time with the diluted coffee fertilizer. Plants will sicken or die if the soil becomes too acidic. Yellowing leaves may be a sign of too much acid in the soil, in which case, abandon the coffee irrigation and repot plants in containers.

Coffee works great on many types of flowering indoor plants but can be used outside as well. Diluted coffee adds just enough organic fertilizer to encourage bushier, healthier plants.

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90,000 for which plants are suitable, how to use cake and ground coffee in the garden and garden

Content:

    1. For which plants are
    2. Methods of use
      • Watering
      • Mulching
      • Supplement
      • compost
      • for soil seedlings
      • Pest protection
    3. Where not to use
    4. Helpful tips

thick as a fertilizer for indoor plants, flowers and gardens. nine0033

The answer to the question of whether coffee grounds can be used as fertilizer is obvious: of course you can! But let's take a closer look at what benefits this brings to plants.

  1. By adding coffee grounds to the soil, especially clay and loam soil, its structure becomes looser, drainage capacity and air exchange improve. In addition, coffee attracts earthworms, which also contribute to loosening the soil.
  2. The smell of coffee can repel harmful insects. He doesn't like cats either. If you sprinkle your garden beds with coffee grounds, you don't have to worry that uninvited visits from your pet will damage tender plantings. nine0008
  3. It is believed that fresh coffee has an increased level of acidity, and top dressing with such characteristics is not suitable for every plant. However, to avoid acidification of the soil, it is enough to shed thick water and then apply in the garden or vegetable garden.
  4. Coffee grounds as a fertilizer are rich in minerals and trace elements. Potassium and phosphorus contribute to good flowering and abundant fruiting. Nitrogen activates the rapid growth of plants. Copper helps to resist a number of diseases. And although the total amount of useful substances in coffee cake is about 2–3%, which means that it can hardly be considered a full-fledged fertilizer, the use of grounds as an organic plant food is fully justified. nine0008

What kind of plants is coffee fertilizer suitable for? Therefore, before you widely use it in your garden, you need to study for which plants it is most effective to use coffee grounds as a fertilizer. It is most useful for flowers that prefer a low pH level - azaleas, hydrangeas, heathers and rhododendrons. Due to the large amount of potassium in the composition, coffee grounds can be used as a fertilizer when growing vegetable crops such as tomatoes, potatoes, cucumbers, and peppers. Feeding fruit trees with sleeping coffee will also help to significantly increase their fruiting. Magnesium, which is part of coffee, is useful for berry bushes.

Magnesium and potassium will help to get a high yield of root crops, while nitrogen is indispensable for green crops. nine0033

Roses, palms, ficuses and ferns, as well as violets and asparagus, respond best to coffee fertilization. When using coffee grounds as a fertilizer for houseplants, it is recommended to shed and dry it first. If you simply pour the rest of the coffee from the cup into the pot, most likely there will be no benefit, but on the contrary, the soil may become covered with a crust and begin to mold. To prevent this, you need to mix the prepared thick with soil suitable for this type of plant. nine0033

Coffee with sugar or milk should not be used for horticultural, horticultural and flower crops, as sugar attracts ants, and milk provokes the development of putrefactive processes in the soil, which can harm the root system of plants.

Methods of use

Watering

Used coffee must be diluted with a sufficient amount of liquid before it can be used as a fertilizer for watering plants. To prepare a solution for 10 liters of water, 1 cup of grounds is required. Cake is poured with a small amount of water and left to swell for about a day. After swelling, the amount of liquid is adjusted to the calculated amount and used for watering plants. nine0033

After feeding the plants with coffee grounds, it is advisable to water the soil again, but with clean water. This technique will allow the minerals to be slowly released, nourishing the plants. When planting bushes, you should spill the ground with coffee solution at the rate of 1 liter under the bush.

Mulching

Coffee grounds can also be used for mulching crops to protect soil from drying out, repel pests and improve soil structure. However, it must be remembered that when using the grounds as mulch, as in the case of using coffee cake as a fertilizer in the garden in the country, it should be thoroughly dried to prevent the development of mold. nine0033

Soil supplement

Dormant ground coffee as a fertilizer can be added to the planting hole or hole before planting to improve soil structure. This technique makes the land more drained and loose, which ultimately has a positive effect on plant health and yield. When used on light soils, the thick acts as a binder. In this case, top dressing is applied to the upper soil layer at the rate of 200 ml per 1 m².

Compost

To speed up the maturation of the compost, it is enough to spill each layer no more than 10 cm thick with coffee infusion. Coffee grounds perform the function of nitrogen components that trigger an exothermic reaction inside the compost heap, in other words, heating it up, due to which the compost matures much faster. This method is so effective that some summer residents specifically purchase inexpensive varieties of ground coffee and sprinkle layers of compost on them.

For seedlings

Recently, the method of growing vegetable seedlings on a coffee substrate has become popular. But in order to prevent depletion of the soil, it is necessary from time to time to feed the seedlings with complex fertilizers. nine0033

Protection against pests

Coffee pomace as a fertilizer in the garden is also very effective for protecting plants from sexually mature individuals of harmful insects - ants, snails, aphids, slugs. According to the experience of some gardeners, coffee can also destroy pest larvae, in particular mosquitoes and garden bugs. This remedy is not as effective as insecticides, but also much safer.

Where not to use coffee grounds

Coffee grounds are rich in nitrogen, so if used in excess, you can burn the root system, which will lead to the death of the plant. nine0033

Poorly dried coffee waste can cause mold and fungal diseases and kill plants. In addition, coffee fertilizer is not suitable for tradescantia, asparagus, geraniums and other crops that prefer more alkaline soil. Top dressing from pomace can change the shade of rose flowers.

Helpful Hints

Dried coffee grounds are very light, so when used dry, even the slightest breeze can blow them off the garden. To prevent this from happening, it is recommended to mix the cake with earth or sawdust and close it shallowly into the soil. nine0033

If the color of the leaves of the plants has changed after treatment with coffee grounds, the use of coffee grounds as a fertilizer should be discontinued. You can carefully strain the coffee infusion and use only liquid for irrigation, and use the thick, for example, to feed conifers.

It is recommended to prepare fertilizer from coffee grounds for summer cottages, using cake from the preparation of only natural coffee. Instant powder and granulated coffee is not advisable to use for this purpose, since their nutritional value is not great. nine0033

the pros and cons of using coffee in the garden and in the garden - an article on TCHK

The advice not to throw away coffee grounds, but to take it under the tomato bush can be found in many collections of non-traditional uses of coffee. Compost, fertilizer, insecticide and soil acidifier - a variety of useful properties are attributed to this product. In fact, everything is not as simple as it seems at first glance. Below, we will look at a few of the main arguments for using coffee in the garden and see which ones should be treated with caution. nine0033

Is coffee a useful fertilizer?

There is a common belief that coffee grounds can act as an ideal natural way to feed the beds: they contain about 3% of useful micronutrients, including magnesium, potassium, calcium and phosphorus, as well as nitrogen. However, "natural" does not mean "safe" and "useful".

According to a 2016 study by Australian scientists, recommendations for using used coffee grounds either directly in the soil or as compost should be considered... anecdotal. Empirically, the Australians have found that this kind of "fertilizer" not only does not improve growth rates, but even reduces them. nine0033

Why? Looks like it's all about the caffeine. There is a lot of it even in the sleeping coffee grounds. Now raise your hand if you remember that caffeine is toxic to other non-caffeine plants. In addition, coffee grounds have antibacterial properties, which negatively affects the natural processes characteristic of composting.

However, one cannot fail to mention exceptions. According to the experience of experienced flower growers, azaleas, roses, hydrangeas and camellias respond well to such top dressing, increasing the number of buds. I like the coffee diet and evergreen shrubs, as well as ferns. nine0033

Coffee acidifies alkaline soil

One of the most common gardening tips about coffee grounds is to use them to acidify the soil. It seems to make sense: everyone knows that coffee is sour. The question is how sour the thick will be.

It turns out not very good.

Although the caffeine is still present in this product, the acid present in the grain is water soluble. Therefore, our drink becomes sour, and not the used grounds, which have a pH close to neutral (from 6.5 to 6.8 pH). nine0033

The conclusion is obvious. Coffee as an acidifier is pure myth. The used grounds practically do not have the acidic properties of the drink.

Coffee keeps pests away

Really does. After all, caffeine is toxic not only to plants, but also to insects. Scientists have already proven that coffee grounds are very effective against bugs and midges. There is a version that it also helps to drive away slugs and snails, but this hypothesis requires additional research.

Coffee is an effective soil conditioner

On the one hand, yes, the coffee grounds add some looseness. However, at the same time, its toxic properties continue to work, which means that the active use of such an additive will destroy the gardener's main friends - worms. Many Internet sources write that worms like coffee, but in reality, such a feast will have an extremely negative impact on their health. Well, then it’s easy to calculate: no worms - no natural “baking powder”.

Coffee against weeds

As we remember, caffeine inhibits plant growth.

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