Coffee grounds in garden

moeptx85April 13, 2014

Does anyone have any information about using coffee grounds in a raised bed garden? I've added a few handfuls around some tomato and pepper plants this spring already. Is there a limit to the amount that can be put down?

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One thing to remember is that they are acidic and you have to know what your plant prefers.

    Bookmark   April 14, 2014 at 12:25AM
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Try the link below. The search widget here is absolutely terrible; so bad that it's easier to google it and look for GW references.

Here is a link that might be useful: GW coffee ground thread

    Bookmark   April 14, 2014 at 12:33AM
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The use of coffee grounds in the garden is well established and can be part of the organic matter all soils need added regularly, but they should not be the only form of OM added to soil.
Coffee grounds, according to tests done by Washington State University paid for by Starbucks, have a pH of 6.2 (slightly acidic, but in the range most all plants find best) and have a Nitrogen level of about 2 percent, Phosphorus level of about 0.06 percent, and a Potash level of about 0.6 percent.
Many people will tell you that earthworms love coffee grounds, but earthworms love any organic matter as does the rest of the Soil Food Web that work on digesting the OM in soils to feed the plants that grow there.
Make coffee grounds part of the organic matter you add to the soil on a regular basis.

Here is a link that might be useful: coffee grounds analysis

    Bookmark   April 14, 2014 at 6:47AM
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Thanks to everyone for the very useful information. My tomato plants seem to enjoy the grounds. I imagine too much might prompt excessive foliage though.

    Bookmark   April 14, 2014 at 4:23PM
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toxcrusadr(Zone 6a - MO)

When it gets hot and dry, they can form a crust that repels water, so that may be the practical upper limit, unless you cover them with some other mulch so they are not on top.

I would guess an inch or two put down over the growing season would be OK. All at once they might leach a bit too much of whatever is left in them. Most of the acid goes into the brewed coffee though, which is why grounds are not very acidic.

    Bookmark   April 14, 2014 at 4:36PM
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johns.coastal.patio(USDA 10b, Sunset 24)

For what its worth, I have a garbage can full of extra potting soil. I mix some coffee grounds and eggshells in there (keeping it all pretty dry). When I go to use it, it should all be nicely aged.

    Bookmark   April 18, 2014 at 6:23PM
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Baby G (Z10, 300?CH, SoCal-LA)(10)

I love the idea of the direct mix in soil.

I kinda think of coffee grounds as similar to blood meal. Free blood meal. I believe it might be smart to limit them to preplanting. I suspect that adding them to a growing tomato plant could backfire, since the high N ratio could encourage more leaf growth than tomato growth.

    Bookmark   April 21, 2014 at 11:44PM
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At 2 percent Nitrogen coffee grounds are unlikely to create the same problems as Blood Meal can.

    Bookmark   April 22, 2014 at 7:00AM
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toxcrusadr(Zone 6a - MO)

The best compost I've seen is about 1% nitrogen so it's almost like side dressing with compost. All depends on your soil and your situation. 'Observe and adjust' is always good advice.

    Bookmark   April 22, 2014 at 12:23PM
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