Composting / RHS Gardening (2024)

FAQs

Are coffee grounds good for the garden rhs? ›

Coffee grounds: provides low levels of nutrients and can either be used in small quantities around plants or composted before adding to the garden.

Turn your pile over and aerate

As mentioned above, getting air to flow through your pile helps speed up decomposition. In addition to relying on the natural matter to create pockets of air, you can turn your heap over regularly to ensure even decomposition while simultaneously aerating.

Aim for a 50:50 Mix of Greens and Browns

Think grass clippings, spent crops, old bedding plants, annual weeds (seed-free so you don't inadvertently spread them about in the final compost), and kitchen waste such as vegetable peelings and fruit peels.

Coffee grounds inhibit the growth of some plants, including geranium, asparagus fern, Chinese mustard and Italian ryegrass. Conversely, grounds (used as mulch and compost) improve yields of soybeans and cabbage.

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.

Turning your compost too much is also possible. “The fungi and microbes that break everything down will keep getting mixed around before they have a chance to get to work,” says Janet Sluis, a horticulturist and curator for Sunset Plant Collection.

If your compost smells sour like ammonia, the most common reason is too much green material and/or a lack of brown material. You should use 2 to 3 times as much browns as greens. Always cover your greens with a layer of browns like leaves.

Anyone who has been gardening for a while knows that peeing in the compost is the thing to do. Uric acid speeds up the compost process and gets you to the end product faster. Even the National Trust in England provides “pee bales” in strategic places in public gardens and parks that the male horticulture staff can use.

You can add several things to compost to speed up the process, including worms, manure, grass clippings, and coffee grounds. You can also mix in a compost accelerator to speed up the process even further.

What is the best compost method for a garden? ›

Trench and pit composting are pest-resistant versions of the heap that put the finished compost right where you'll grow. Dig a trench or a hole a few feet deep. Fill it with organic waste and cover it with at least six inches of soil. The bacteria and worms will start breaking down your waste in no time!

Cool, slow composting is an easy method for people who don't have the time or desire to tend to a hot compost pile. Slow cold composting can take three to six months, and sometimes even longer, but with a lot less effort on your part.

The 3-bin system is useful primarily because it offers space to have compost at 3 different stages of decomposition. For example, you could put all your compost in one bin for a period of time — then stop adding to it, and start adding to a second bin while the first one finishes decomposing.

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.

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.

She recommends that grounds make up no more than 15 to 20% of the total compost volume. Because they are acidic, coffee grounds make good acid mulch. Of course, too much of anything is just too much, so apply coffee grounds in limited amounts. Kit recommends a layer no thicker than half an inch.