Lewis Spencer adds: 'To use coffee compost, simply sprinkle the grounds directly onto your soil and lightly rake it in. Coffee grounds add organic material to the soil, helping water retention, aeration, and drainage. 'Leftover diluted coffee can create a liquid plant fertilizer, too.
Spread on planting beds like mulch, grounds are said to repel cats, fertilize soil, kill slugs and keep weeds at bay. A coffee mulch is also rumored to beckon earthworms and acidify soil. Other gardeners work coffee grounds into beds, swearing it aerates and acidifies soil.
How Often Should You Add Coffee Grounds to Plants? You can fertilize houseplants an average of 7 to 10 days in a row, but no more, as there is a risk of over-acidification of the soil. A cup of ground coffee should be added to the compost once a week.
Using Coffee Grounds as Fertilizer
To use coffee grounds as a fertilizer sprinkle them thinly onto your soil, or add them to your compost heap. Despite their color, for the purposes of composting they're a 'green', or nitrogen-rich organic material.
Used coffee grounds are neutral. If you rinse your used coffee grounds, they will have a near neutral pH of 6.5 and will not affect the acid levels of the soil. To use coffee grounds as fertilizer, work the coffee grounds into the soil around your plants. Leftover diluted coffee works well like this too.
Like any type of fertilizer, coffee grounds are only effective when used sparingly. It is never a good idea to add too much, as that could do more harm than good. The proper proportion is usually around 4 to 1, or twenty-five percent of coffee grounds to mineral soils by volume.
Compost coffee grounds for a vegetable garden instead of using them directly. Remember, coffee grounds are not good for tomatoes or seedlings. Get a soil test, especially if your plants are not thriving or you want to change the acidity of the soil.
It's okay to water plants with leftover coffee or to add coffee grounds to the compost pile but learning when and why to use coffee in the garden will protect your plants. Only use black, unflavored coffee with this method to offer plants a source of nitrogen which can fertilize certain indoor and outdoor plants.
Coffee grounds (and brewed coffee) are a source of nitrogen for plants, producing healthy green growth and strong stems. Coffee also contains calcium and magnesium — both of which are beneficial to plant health. To use coffee as a plant fertilizer, you'll need to dilute it. It should look like weak tea.
Since coffee grounds have such a pungent and intense smell, mosquitoes do not like to come near it. Mosquitoes are repulsed by all types of coffee, whether it is fresh, used, or burnt. The most effective way to use coffee grounds for mosquito control is by burning them, as it creates a stronger aroma.
Coffee grounds are rich in nutrients, especially nitrogen. They also have some amount of other nutrients like potassium and phosphorous. Overall, this means that adding coffee grounds to your garden can work fairly well as a fertiliser. Coffee should be spread in a thin layer, rather than being clumped in one place.
Coffee grounds are highly acidic, they note, so they should be reserved for acid-loving plants like azaleas and blueberries. And if your soil is already high in nitrogen, the extra boost from coffee grounds could stunt the growth of fruits and flowers.
Coffee plants don't like to stay wet, so water every 1 to 2 weeks, allowing the potting mix to dry out halfway between waterings. You'll need to water more often in brighter light and less often in lower light, says Marino. But always poke your finger into the soil to check the moisture level before giving it a drink.
You may love your morning coffee, but ants could do without it. Another natural way to deter ants, sprinkle coffee grounds outside and around your garden. The smell repels them and they'll be looking for a less caffeinated place to hang out. Want to keep your home clean and clear of ants?
The fridge is not the place to store coffee in any form, ground or whole bean even if in an airtight container. It isn't cold enough to keep your coffee fresh, and because coffee works as a deodorizer, it will absorb all the aromas in your fridge.
Excessive acidic soil can kill or hamper the growth of plants like asparagus fern, Chinese mustard, Italian ryegrass, lavender, orchids, rosemary, tomatoes, and geranium. The roots of these plants are also not potent to absorb the nutrients added by the coffee grounds in the soil.
The shells also contain other minerals that help plants grow, including potassium, phosphorus, and magnesium. Eggshells are, therefore, an effective and inexpensive fertilizer for outdoor garden soil and houseplants.
Most plants will grow well in a slightly acidic to neutral pH (between 6.0 to 7.0) but others prefer acidic or alkaline soil. Therefore, scattering coffee grounds indiscriminately round all your plants is not a good idea.
'Coffee grounds are an excellent houseplant fertilizer due to their high nitrogen content (about 2 per cent) that releases slowly into the potting media as they decompose. However, coffee grounds have more to offer to plants than just nitrogen,' she says.
Coffee contains a lot of nitrogen, which not only kills off weeds and bacteria but can also help certain types of plants (a.k.a those that prefer more acidic soil) flourish. Plus, your daily cuppa also contains significant amounts of magnesium and potassium, both of which are key factors in plant growth and health.
The absorption of these nutrients encourages more rapid growth in the plant. Therefore, pouring soda on plants, such as Classic Coca Cola, is inadvisable. Coke has a jaw dropping 3.38 grams of sugar per ounce, which would certainly kill the plant, as it would be unable to absorb water or nutrients.
While many budding gardeners may be concerned that coffee grounds can attract pests, the reality is quite to the contrary. In fact, when implemented correctly, coffee grounds can be an effective way to repel certain pests such as wasps, snails, and mosquitoes.
There are a select few plants that can benefit from fresh grounds—including acidity-loving Hydrangeas, Rhododendrons, Azaleas, Lily of the Valley, blueberries, carrots, and radishes—but generally, most common houseplants will prefer low to no acidity.
Sarah says the key is composting them first. "Give it six months to a year. The compost will break down the phytotoxins, and you'll still get the great benefit to the soil from using them."