If you are anything like us, you probably love a good cuppa coffee (or 2) – but what do you do with your leftover coffee grounds?

Many avid gardeners use it in their garden – and so do we. Most plants love it because of the often high Nitrogen content in coffee. Nitrogen is a component of chlorophyll and therefore essential for photosynthesis. It is also the basic element of plant and animal proteins, including the genetic material DNA and RNA, and is important in periods of rapid growth. Plants use nitrogen by absorbing either nitrate or ammonium ions through the roots.

Did you know that the main nitrogen component in DIY organic fertilizers is seedmeal? If you think about it, a coffee bean is a processed seed. Depending on the exact beans and extraction process, “the carbon to nitrogen ratio of coffee grounds can be as low as 11:1, an ideal ratio for plant and soil nutrition,” according to WSU extension.

Coffee grounds are also a rich source of fatty acids, essential oils and nutrients that enrich soil.

Ok, we’re sold!

But wait . . .

Not All Plants Like Coffee

Although most plants benefit from the nutrient boost associated with adding coffee grounds to the soil or compost, some plants may be harmed by the addition. Exposure to coffee grounds has caused inhibited seed germination and stunted plant growth in plants including white clover, alfalfa, Chinese mustard, asparagus fern and geraniums.

With this in mind, let’s take a loook at 4 very useful ways to use your leftover coffee in the garden:

1. Mulching

Mix used coffee grounds with your favoured mulching material – especially at the base of fruit trees.

NOTE: Compact coffee grounds can hamper vital air flow, which is essential for plant growth, hence the reason for mixing it with other mulching material. Compact coffee grounds also go mouldy and this invites unwanted risks of  fungal infections.

The coffee grounds will break down relatively quickly as worms and soil microbes go to work, and when it does you can add more.

Growing Home ~ Young Paw Paw thriving in a mulch mixed with coffee grounds


2. Compost

Add used coffee grounds and filter paper to your compost pile. Decomposing coffee grounds have their own fungal and mold colonies and those fungal colonies tend to fight off other fungal colonies.

Keep coffee grounds to no more than 20 percent of the material included in your compost. Coffee grounds are considered green material, like fresh grass clippings and kitchen waste, and must be balanced with brown material, such as dried leaves, to compost properly.

3. Vermicompost

Worms love coffee grounds! Don’t overdo it though… too much can go rancid and the worms don’t like this.

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4. Dressing for Heavy Feeders

Coffee grounds make an excellent side-dressing for leafy greens like spinach & kale; and fruiting veggies like tomatoes and squash. Loosely work in some coffee grounds into the top 6cm of soil around the plants. Make sure you don’t compact the soil as this will prevent air flow.

Do you use coffee grounds in the garden? We would love to hear about it!

Till Next Time,

Shireen & Kathy

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