7 smart ways to use coffee grounds in the garden

How to use coffee grounds in the garden?

Using coffee grounds in the garden is very easy.

In most cases, what you’ll need to do is to just spread coffee grounds around the plants.

There is also the option of using the grounds as part of a compost. In that case, grounds should be part of a composting mixture, along with leftover food, leaves, sand, and other such elements.

Use these grounds for best effects

In gardening, you can use either dried coffee grounds or freshly used coffee grounds.

We typically like to dry and store coffee grounds in a dark space with a room temperature. They have come in handy on multiple occasions, including some unexpected yard work. However, we have also used freshly used coffee grounds! Both should work equally well.

As coffee contains caffeine, we need to remember that one of the caffeine’s functions is to produce allelopathy in plants. Allelopathy reduces competition from surrounding species by suppressing their growth. That said, using a large amount of coffee grounds can create adverse effects in plants.

Therefore, it is best to use USED coffee grounds (rather than fresh coffee grounds). Used coffee grounds contain reduced levels of caffeine, and are thus best to use in gardening.

Another consideration to make is a choice between organic vs inorganic coffee grounds. If you would like to grow an organic garden free of pollutants and pesticides, it is important to use organic coffee grounds.

7 ways to use coffee grounds in the garden

So, how can you use coffee grounds in the garden? Here are 7 ways that may serve as an inspiration for you and your loved ones:

✔️ Coffee grounds as mulch

Mulch is a great additive to improve the quality of soil. In the yard work, professionals use two types of mulch:

• Organic mulch, which includes hardwood chips, pine straw, grass clippings and crushed leaves, and
• Inorganic or synthetic mulch, which includes pebbles, crushed rock, plastic or rubber mats or chips.

Mulch has multiple benefits: 1) increases the fertility of soil, 2) maintains moisture, and 3) protects from weeds and harmful insects. Coffee grounds can be added to mulches to add extra qualities to the mix.

✔️ Coffee grounds as compost

Compost us a mix of organic matter that has been decomposed through a process called “composting.” We can throw almost any type of organic waste into the compost, including all kinds of food leftovers that we would otherwise throw in trash.

Coffee grounds can facilitate the composting process. They enrich compost by releasing nitrogen. Further, they speed up decomposition of the mix.

Composts are great to be used in the garden as soil conditioners.

✔️ Coffee grounds as fertilizer

Coffee grounds can be a fantastic fertilizer. In order to use them as such, simply spread them around the plants. There are several benefits of using coffee grounds as fertilizer:’

• Retains moisture and improves soil drainage.
• Attracts beneficial earthworms and microorganisms to improve soil fertility.
• Increase acidity of soil, which is great for acid loving plants.

✔️ Coffee grounds as a repellent for snails

Snails and snugs feed themselves on plant leaves. It is better to keep them away. Some gardeners report that coffee grounds can help with that. It appears that coffee emits scents that repel those pests.

✔️ Coffee grounds as a repellent for cats

Cats do not seem seem to be great fans of coffee smell. Therefore, spreading coffee grounds around the plants can keep cats away.

✔️ Coffee grounds as a repellent for deer

With deers, coffee works in the same way as it works with cats: the smell keeps the animals away.

✔️ Coffee grounds as a natural pesticide

It seems that coffee’s scent is attractive mostly only to humans. Coffee can serve as a natural pesticide. However, be warned: this may deter harmful and beneficial insects, like the bees.

Plants that love coffee grounds

It is important to remember that not all plants like coffee grounds. While some plants may in fact be harmed with the excessive use of coffee grounds, some plants appear to thrive with coffee grounds as a fertilizer. In particular, acid-loving plants may love coffee grounds:

• Vegetables: sweet corn, beans, broccoli, turnips, squash, onions
• Fruits: cranberries, blueberries, huckleberries
• Trees: evergreens, beech, willow, oak, dogwood.

Plants that DISLIKE coffee grounds

However, a large number of plants prefer more alkaline soil. These plants, thus, do not like coffee grounds. Here are some examples of plants that should NOT use coffee grounds:

• Trees: Silver maple, Green ash, burr oak and Austrian Pine
• Shrubs: lilac, boxwood, oleander, barberry, juniper
• Perennials: geranium, clematis, coral bells, salvia, sweet pea
• Vegetables and herbs: lavander, thyme, oregano, cabbage, beets, cauliflower, cucumber, celery
• Ericaceous plants: Rhododendron, Camellia, Azalea, Pieris, Japanese maples (Acer)

Can you use too much coffee grounds in the garden?

Nevertheless, adding coffee grounds in your gardening routines need to occur with moderation, even for acidic-loving plants. Experts recommend a layer of maximum one inch around the plants. Also, we should wait until one layer has been completely decomposed before putting another layer.

When it comes to composting, coffee grounds are considered to be “green material.” Therefore, experts recommend using one part of green material to three parts of brown material (like dry leaves).

According to Soil and Plant Laboratory Inc., Bellevue, WA, composting with coffee grounds improves soil when 25-35 percent by volume coffee grounds are blended with mineral soils of any type.

Regardless, Dr. Paul Hepperly explains that the soil should have an organic matter of 5% to 8%. At some point, if we keep adding coffee grounds to the soil, it will reach the eight percent threshold of organic material, and the results will stop being rewarding.

❌ Coffee grounds can be detrimental to positive pollinators

While coffee grounds can beneficially deter deer, cats and snails, they can also deter positive insects, such as wasps and bees. Wasps and bees are actually crucial to the growth of the plants. Without them, pollination cannot take place, and flowers will not bloom.

❌ Coffee grounds can destroy plants that like alkaline soil

You need to stay in charge of your garden. The use of coffee grounds need to be controlled with utmost care. As discussed earlier, coffee grounds are acidic, so they can destroy your plants if they do not like acidity. Also, coffee can have phytotoxic effects on plants, which can lead a reduction in the plants’ growth.

❌ Coffee grounds can reduce growth of some plants

A study made in 2016 on different plant categories (broccoli, leek, radish, viola and sunflower were used) concluded that using coffee in the garden can reduce their growth. This happens more likely due to the phytotoxic effects of coffee.

❌ Coffee grounds can kill earthworms and bacteria necessary for plants

Caffeine is a powerful insect repellant and antibacterial agent. This study from 2016 showed that coffee has powerful nutrients with antioxidant and antibacterial properties, which means that coffee may also kill earthworms and bacteria necessary for plants.

Owly’s conclusion

Coffee grounds can be extremely helpful in the garden. We can use them in a variety of ways:

• compost,
• fertilizer,
• mulch,
• pest and insect repellent.

However, as some gardeners praise their crops after adding coffee grounds, we need to fully understand how coffee grounds can impact our plants, flowers and other crops.

Coffee is known to be acidic. Therefore, it is best to use them with plants that like acidity (and never with plants that prefer more alkaline environments).

Further, while coffee deters harmful animals and insects, it can also deter beneficial insects like bees.

Coffee can also reduce the growth of some plants, which gardeners certainly do not want.

An informed, educated use of coffee grounds is always advisable, and the conditions of each garden need to be taken into consideration too. All in all, we are for the use of coffee, as we do not like to see good coffee going to waste, even if it has already been used.

What do you think?

What do you use coffee grounds for in your garden? Did you accidentally damage your plants with the use of coffee grounds? What do you recommend to use coffee grounds for in a yard?

Let us know in the comments!