Coffee Grounds for Plants, Used or Fresh and How Much

Coffee – Gramma always said, “Coffee is the elixer of life”. Grampa always said, “Coffee Grounds are the elixer of life in my garden”. 

If you drink coffee, you know it leaves us with a wonderful by-product, coffee grounds. You may also know used coffee ground for plants in the garden does several beneficial things. Drip coffee grounds retain more nutrients than boiled coffee grounds. Believe it or not, not everyone uses a coffeemaker.

Fresh or unused coffee grounds can be used in the garden. Think of fresh or unused coffee grounds  as ‘hot or green manure’ that needs to be aged. Unused coffee grounds are best put in the compost file to heat it up. You can also till them into the soil at the end of the season which will give them time to breakdown and add nutrients to your soil.

Coffee grounds contain nitrogen, calcium, magnesium, phosphorus, potassium, and trace amount of minerals including copper. These nutrients aid the plant’s growth. Our soil and compost love the coffee grounds for this reason. If you are fortunate to have large amounts of grounds then it would be best to put them in the compost or work into the soil at the end of the growing season.

The earthworms and worms of all types love the grounds as they provide food for them. The worms derive nutrition from the grounds and this increases their production which means aeration of the soil, by breaking it up, mixing in air, and their worm droppings. This in turn improves the soil structure, water movement, nutrients in the soil, and ultimately increases the plant growth.

Adding coffee grounds to the compost pile increases the internal temperature of the pile, it heats up. The additional heat helps to speed up the decomposition of the other components such as kitchen waste, leaves, grass clippings, etc. The end product is nice ‘black gold’ nutrient rich compost. Try not to exceed more than 25% of the compost pile’s content with coffee grounds or the balance will be off and the speed of the decomposition will be affected.

Coffee grounds for plants as a fertilizer is a common practice. Many go out and place generous handfuls of the used ground around their plants and after a few days they find their plants are struggling and starting to turn yellow.  Not all plants like coffee grounds because coffee grounds increase the acidity of the soil. Even plants that like an acidic soil may overdose if given too many coffee grounds all at one.

The acid loving plants are the ones that will thank you for a dose of coffee grounds, especially blueberries and evergreen plants. Plants that like a neutral or alkaline PH may not be as happy with you if given a dose of coffee grounds because the grounds lower the ph making the soil more acidic.

Exactly what is acidic soil? Acidic soil has a PH between 4.0 and 6.8. What is PH? In very basic terms, PH is the ‘power of hydrogen’, the relative value of hydrogen in a substance. The more hydrogen ions in the substance, the more acidic it is. This is measured on a scale of 0 to 14. A value 6.8 and under is considered acidic or sour, 7.0 is neutral and 8.0 to 14.0 is alkaline or sweet.

 Common Acidic Loving Herbs: (some herbs can be in more than one category)


Start out by giving your plants just a small amount of coffee grounds. Don’t go by everything you hear and or read. My horehound, basil, and pepper plants may love the addition of a weekly dose of coffee grounds and thrive. In reading this, you decide to do the same thing except your plants don’t like it and you’re wondering why.

The key is knowing the ph of your soil and what ph your plant likes. Then start out gradually with giving your plants a dose of coffee grounds. Try just a teaspoon around the base of the plant, not next to its stem, but under its drip line and gently scratch in into the surface of the soil, no more than 1 inch deep. Wait a week and then try it again. After a couple of weeks increase or decrease the amount or don’t give any depending upon what your plant is doing.

We also use coffee grounds for slug and snail control. It has decreased their population; the slugs don’t like to cross the barrier of grounds as they are sharp enough to penetrate their bodies.  I like to place a ring of coffee grounds around the plants but at a good distance from their drip line. You must replace them after a rain. Using coffee grounds is a good alternative to the high priced slug bait products.

Some use the grounds as a deterrent for ants. I haven’t tried it and don’t know anyone who has. I will give it a shot this summer and report back with the results.

Used coffee grounds can be frozen or placed in an airtight container to keep over the winter and start using as soon as the weather permits. If the coffee grounds mold, use can still use them without any problems. They will mold if not completely dry before storing them.

Try coffee grounds in the garden and the compost pile. Check your soil’s ph level and whether your plant is an acid loving plant and then try coffee grounds for plants. Remember to make notes of how much you used, how often, and what works and what doesn’t. 

Happy Gardening!

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