Feed your garden: Coffee grounds, eggshells & wood ash

What do used coffee grounds, broken eggshells and ash from your fireplace all have in common? They can all feed your garden with important nutrients! Plus they are all organic soil amendments, which is always an added bonus when gardening!

Organic soil amendments

Garden soil is the most important part of a successful garden, but it doesn't get that way on it's own. While it may start out as what we would call 'good' or 'bad' soil, it can be changed in many ways. 

For instance, certain vegetable plants add nitrogen to the soil while others use it up. Companion planting can be used to balance these additions and subtractions but sometimes you have to turn to soil amendments to fix what's wrong.

You garden needs nutrients to support healthy growth. While there are lots of nutrients that go into healthy plants the three main nutrients are nitrogen, phosphorus and potassium.

Unfortunately nitrogen gets used up pretty fast, so it's important to add it back. This is why many gardeners fertilize regularly. Both potassium and nitrogen are water soluble and can get washed away with heavy rains. Phosphorus is essential for producing flowers so your flowering plants will have a higher phosphorus requirement.

When certain nutrients are in short supply plants can become ill with problems like blossom end rot or magnesium deficiency. These can quickly destroy your harvest or stunt the growth of formerly healthy plants.

Homemade, organic soil amendments

If you're anything like me you only want to turn to chemically produced additives in an extreme emergency, so the first things I reach for are always organic soil amendments. (Before treating your soil with an alkaline or acidic amendment, you should find out the PH of your soil first. You can find your soil PH from a simple soil test kit.)

Coffee grounds, used: 

Contains potassium, phosphorus & nitrogen plus small amounts of copper, magnesium and calcium.
  • May be slightly acidic. 
  • Deters slugs when sprinkled in a ring around the plants. 
  • Earthworms love them and gardens love earthworms! 
  • Betters the texture of some soils. 

Egg shells: 

Contain calcium carbonate.
  • Grind in a food processor or coffee grinder to create an eggshell powder for faster absorbancy when adding to soil. 
  • Slugs hate them. Crush by hand and place around plants to deter slugs. 
  • Place a tablespoon of crushed or powdered eggshells into the hole before planting tomatoes, squash, peppers and other vegetables that are susceptible to blossom end rot (calcium deficiency).

eggshells, dried and crumbled ready for use in the garden

Wood ash: 

Contains calcium, phosphorus and potassium.
  • Alkaline, apply directly to the garden in small amounts if you have acidic soil. Can be used in place of lime. Make sure it is ash from wood, not burned garbage or glossy papers. 
  • Sprinkle in a ring around plants that prefer a more alkaline soil and it will deter slugs also. (this is not a one size fits all slug repellent as acid loving plants will not thrive when treated with wood ash) 
  • Add small amounts to compost to help maintain a neutral condition. 

All 3 of these can composted and I just add them to the pile as I acquire them. (take it easy on the ash though) I like to keep a small container of each on hand for use when planting.

coffee grounds, wood ash & eggshells for the garden

It's important to know what kind of soil your plants prefer and their nutritional requirements. For instance Lavender likes a more alkaline soil. I sprinkle wood ash around my lavender in fall, during winter and early spring. Tomatoes often need added calcium so I always add ground eggshells when planting those.

You can find specific information on nursery tags, seed packets, in catalogs when you order seeds etc...then you can decide what you need (if anything) to add to your soil. You can also Make Your Own Organic Liquid Fertilizers if your plants need an extra boost during the growing season. Happy growing!

Want more posts on cheap garden hacks? Click here for my other posts on Frugal gardening!


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  1. wonderful information. I'm hitting my head as I should've found out why my blossoms failed, now I know. Thanks for the garden help.

  2. Great info! I have heard this, but haven't tried it. Thanks for sharing with SYC.

  3. Great information and we have heaps of ash from our wood stove. Thanks for sharing this with us at Good Morning Mondays. Blessings

  4. Wow! This is so helpful! I love your tips.

    Definitely pinning this to my Deliberate GARDENING board.

    Thank-you for sharing and for linking up to the #SHINEbloghop.

    Wishing you a lovely day.

  5. Some really great information, Gladiola I found this.