Coffee Grounds for Plants (2024)

FAQs

What kind of plants do you put coffee grounds on? ›

Coffee grounds are neutral to slightly acidic (pH can range from about 6.2 to 6.8), with fresh grounds containing more acid, which can affect soil pH. Acidic-loving plants such as azaleas, blueberries, hydrangeas, rhododendrons, and roses will benefit from a sprinkling of coffee grounds around the base of plants.

Avoid using coffee grounds on alkaline-loving trees, such as linden, ironwood, red chestnut and arborvitae. Coffee grounds used as mulch or compost inhibit plant growth on geranium, asparagus fern, Chinese mustard and Italian ryegrass.

You can, but it should not be more than a thin sprinkling. If you add too much, the coffee grounds will form a dense layer on the surface of the potting soil that is impenetrable to water.

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.

For example, avoid adding any caffeine to plants that are germinating. Freshly seeded areas should be avoided as well. Fresh grounds, and caffeine in general, have allelopathic properties. This can stunt plant growth and do more harm than good.

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.

Ants especially don't like them - both grounds and the acids damage their exoskeletons. Use spent grounds to keep ants out of the house by laying down a 2 inch wide line around the foundation and entrances. It also works for many kinds of worms, snails, slugs and other insects.

We recommend using about a teaspoon of coffee grounds per gallon of water. Let the coffee grounds and water mixture steep for a few nights, stirring occasionally, then strain the liquid through a cheesecloth. The remaining liquid can be used to water, and gently fertilize, your houseplants.

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.

Should coffee grounds be wet or dry for plants? ›

Ensuring a balanced mix of 'wet' and 'dry' materials is the best way to achieve good compost. The nutrients contained in coffee grounds will be recycled back into the soil when finished compost is used as a mulch or dug into the soil. Also add any un-drunk coffee to dry material in a compost bin.

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.

Excess coffee grounds, if applied to the soil before composting, have multiple effects on the soil system. In addition to microorganisms tying up nitrogen temporarily, the caffeine residues in the spent coffee grounds can suppress germination and slow the growth of some plants.

The shell of a chicken egg is comprised of about 96% calcium carbonate (CaCO3). Calcium is an essential plant nutrient and moderates soil acidity. Fast-growing plants deplete the soil of calcium very quickly so egg shells are an ideal supplement and feed for outdoor flowers, vegetables and fruit trees in your garden.

Coffee grounds are packed with nutrients that tomato plants love, like nitrogen, potassium, and phosphorus. They help improve soil structure and promote microbial activity, which can lead to healthier, more robust tomato plants. Plus, they may even help deter certain pests.

As for eggshells, LA Compost praises their contribution of calcium, another common ingredient in fertilizer. The added boost is particularly useful for growing plants like tomatoes and peppers, which may suffer from calcium deficiency.