Wondering how to use coffee grounds in your garden? Well, it turns out that your caffeine addiction might just be your garden's saving grace and the next step for upping your allotment's sustainability.
If you're lucky enough to have one of the best coffee machines in your possession then you may be all too familiar with having to dispose of used coffee grounds after each delicious cup. Coffee grounds that you might have only previously seen as trash are your garden's treasure, as using the grounds to nurture your plants and soil is the latest sustainable garden idea we can't get enough of.
With this in mind, we chatted with horticulture and garden experts to determine how to use coffee grounds in your garden and also get to the bottom of exactly why they're so good for your plants and soil quality.
How to use coffee grounds in your garden
Luckily there's more than one way to use your coffee grounds in your garden, similar to using tea bags in your garden. Whether your plants need an extra pep in their step or your veggies have fallen victim to a slug invasion, this natural solution is more versatile than you think.
Here are the three plant-friendly ways of using up those rich coffee grounds...
1. Fertiliser
If you're trying to keep up with the garden trends this year or are perhaps looking to recreate the wildflower garden border trend then coffee grounds are a great plant fertiliser.
Russell Birchell, Founder of Hedging UK says, "Coffee grounds imbue the soil with vital nutrients such as potassium, nitrogen and phosphorus, leading to healthier plant growth and greater blooming potential in the long run."
When it comes to how you should spread your coffee grounds and how often there's a little more choice to it than simply dumping the grounds into your soil and calling it a day.
“Coffee grounds can be used in various ways in the garden, " agrees Peter Ivanov, Professional gardener at FantasticGardeners. "For example, they can be incorporated into compost bins or worm bins to add nitrogen and increase microbial activity, which will make them more nutrient-rich."
Russell has always had an interest in horticulture, right from the moment he built a polytunnel on his parent's farm when he was younger. From this, he went on to grow perennial plants and sell them to customers, until finally he went on to sell hedging plants and founded Hedging UK.
2. Mulch
If you don't have a compost bin then you can also use the grounds directly as a mulch around acid-loving plants, explains Peter. Plants such as azaleas, rhododendrons, blueberries and roses are particularly fond of acidic mulch as they naturally help lower soil pH over time.
Peter also suggests mixing the grounds into the soil as this can improve soil structure and drainage, however, he does warn against overuse as they're not compatible with every plant species.
"It’s not suitable for all plants and the main problem is that if they’re applied in a larger quantity to the top of the soil, their small particles can clump together and prevent water and air from reaching the roots of the plants," explains Peter.
To prevent this he recommends using the coffee grounds on the border soil of established plants only and making sure you aren't putting them in the same spot every time. If you do finish yourself adding multiple grounds to one spot then Russell says simply rake them deeper into the soil.
3. Pest control
You may have mastered how to keep the ants away or believe in the powerful pest control properties of Irish Spring Soap but when it comes to snails and slugs it seems impossible to deter them. Especially when we're vegetable growing, using heavy chemicals to kill the slugs is just not an option, lucky for us coffee grounds can help with this too.
"Coffee grounds can act as a great deterrent for slugs and snails because their rough texture can irritate their soft bodies, making it uncomfortable for them to crawl across the soil," says Peter. It's not just the texture of the grounds however, the actual caffeine content is also believed to have a toxic effect on slugs and snails too.
Peter does point out that the grounds alone won't completely deter the plant-eating pests, and suggests using them alongside other types of barriers and traps too. The grounds as pest control will also need to be applied often as they will deteriorate, especially if it's rained recently.
incidentally using eggshells in your garden can also help to deter larger pests.
Peter has been a gardening and plant expert at Fantastic Gardeners for over 8 years, he is now one of the company's top-performing experts and manages over 6 teams of gardeners. He works on creating stunning landscapes and prioritises sustainability in his gardening methods.
Where is the best place to put coffee grounds in the garden?
Although adding coffee grounds is one of the easy gardening tips that every gardener should know, there are a few do's and don'ts. Due to the acidness of the grounds, there are some plants you should not be putting them anywhere near for example tomato plants and seedlings as this can interfere with their growth and germination. Not what you want when you've only just started vegetable gardening for beginners.
"It’ll be best to compost them first to reduce their acidity and allow them to break down, making them suitable for a wider range of plants," explains Peter. Once you've composted your grounds then they should be safe to use for the rest of your plants and flowers, but you must add the grounds gradually.
Peter warns of creating a water-restricting barrier with the grounds which could eventually cause your plants to wilt and die. He recommends adding a layer of another type of organic mulch, such as wood chips, just to stop the grounds clumping together and stop water movement.
It's all well and good having the best plants that every garden needs, but if they're not thriving it can all be a little anti-climatic. Adding coffee grounds to your less-than-happy plants can be exactly what they need to get them blossoming once again, and why not, you'd only throw them away.