I have been working with coffee grounds for a few years now, and find myself consulting on the topic with people from all around the world – on better ways to collect it, use it, or sell it.This is a long way from where it all started – throwing handfuls of spent coffee grounds into compost and wondering what on Earth I was doing! .
How to Use Coffee Grounds in Your Garden
If you make a daily pot of coffee, you have a fabulous source of organic matter right at your fingertips.Your coffee grounds may be brown in color, but in compost jargon they are green material, meaning an item that is rich in nitrogen.However, it must be balanced with brown compost material, which includes dry leaves and newspapers.In smaller amounts, especially when mixed with dry materials, coffee grounds will give up their nitrogen.The small particles can lock together, creating a water resistant barrier in your garden.It also makes a great foliar feed you can spray directly on the leaves and stems of your plants.Your acid-loving plants like hydrangeas, rhododendrons, azaleas, lily of the valley, blueberries, carrots, and radishes can get a boost from fresh grounds.This could be a good use for coffee that is getting old in your pantry or a type you bought for visiting friends but isn't your usual cup of joe.One 2016 research study found that using spent coffee grounds in growing broccoli, leek, radish, viola, and sunflower resulted in poorer growth in all soil types, with or without additional fertilizer.The good news is that the coffee grounds improved the water holding capacity of the soil and decreased weed growth.The researchers think the poorer growth was due to the plant-toxic compounds naturally present in the coffee grounds. .
A Common-Sense Guide to Using Coffee Grounds in the Garden
Mulching is incredibly beneficial but it’s notoriously difficult to come by compost, straw or other organic matter in large enough quantities at a low enough price.The reason for this could be that coffee beans contain caffeine, which is said to suppress the growth of other plants to reduce competition for space, nutrients, water and sunlight.This turns them into a barrier that will resist water penetration and eventually result in plants dying of thirst.Many of us will have dumped the cold remains of a forgotten coffee in a plant pot at some point, and then perhaps wondered if it was the wrong thing to do!But it turns out that coffee grounds contain a good amount of the essential nutrient nitrogen as well as some potassium and phosphorus, plus other micronutrients.Your compost heap’s tiny munchers and gnawers will process and mix them effectively, so using coffee grounds in this way is widely accepted to be safe and beneficial.One word of warning though: coffee grounds may not have much effect on pests, but they can be harmful to pets in large enough doses.But if you have a dog that insists on sampling anything that smells halfway agreeable, it would be wise to avoid laying coffee grounds directly onto the garden. .
What Plants Like Coffee Grounds?
Not all plants will thrive on a coffee diet, so it’s important to avoid throwing those beans around.If you often have cats digging around in your plants or using your garden as a litter box, you may want to consider adding coffee grounds to the soil.The plants that like coffee grounds include roses, blueberries, azaleas, carrots, radishes, rhododendrons, hydrangeas, cabbage, lilies, and hollies.You’ll want to avoid using coffee grounds on plants like tomatoes, clovers, and alfalfa.When in doubt, it’s probably safer to put your used coffee grounds in the compost bin — or check out our list of other uses for them!Using coffee grounds in your garden has its share of pros and cons, and we hope this article has answered your questions.Coffee can impede plant growth, but it may also keep away certain pests or alter the pH of your soil in a useful way.Plants like carrots, roses, cabbage, and hydrangeas like coffee grounds — but avoid using them on tomatoes and clovers. .
Gardens: so you think coffee grounds are good for plants
A quick internet search for “coffee grounds + plants” will draw up close to four million hits, with consistent claims they can add essential minerals to the soil, boost populations of friendly soil bacteria and even reduce the pH of growing media for acid-loving plants like rhododendrons.Always keen to try out a quirky horticultural tip, and being a bit of a caffeine fiend, I decided to put the theory to the test this summer on two identical vegetable beds containing a mix of tomatoes, lettuce, herbs and flowers.One of the key functions of caffeine in the plants that produce it is allelopathy – the ability to reduce competition from surrounding species by suppressing their growth.There is a stack of studies to suggest it also stalls root growth in young plants, preventing their uptake of water and nutrients.I love a quirky piece of hort advice, and some are repeated so often you assume they are true, but often they call them old wives’ tales for a reason. .
What Plants Like Coffee Grounds and Eggshells?
Instead of throwing eggshells out you can make it a habit to store them in jar on your kitchen counter then later add them as organic compost to your plants’ soil.Crops that attract snails such as basil, cabbage, lettuce, marigolds and strawberries will certainly benefit from a sprinkle of eggshells onto their soil.Plants that tend to like coffee grounds include hydrangeas, gardenias, azaleas, lilies, ferns, camellias and roses. .
Spent coffee grounds improve the nutritional value in elements of
Lettuces cultivated in agricultural soils amended with SCG had significantly higher levels of several essential (V, Fe, Co, V, and probably Mn and Zn) and toxic elements (Al and probably As), without reaching their toxicological limits. .