Tomatoes and coffee grinds

11 years ago

FYI We are in the middle of summer here in Sydney

I had a great experience with coffee grinds several years when I was living in a desert area and growing succulents.

Being a total brown thumb back then I assume grinds were magic but they were probably retaining moisture in the potted plants in 100+ degree heat and feeding them some good nutrients.

I've recently gotten into gardening and planted a couple of vege patches which are - to my total surprise - actually thriving! Well apart from lettuce which I transplanted and subsequently killed but all in all very happy.

My local coffee place gave me 5 gallons of grinds when I asked for them

I added coffee grinds around beans, zucchini, tomatoes, succulents, marigolds and amaranth. I added this straight but only a thin layer around these plants.

The beans, zucchini and tomatoes now have much lighter new growth - almost a bright lime as opposed to the dark healthy green of the rest of the foliage. Some leaves are even half and half - you can clearly see when I added the coffee grinds!

Everything still looks healthy, flowers are forming on cukes and zuch's, tomato plants have just started fruiting...

Is this OK? I am finding the change in leaf color unsettling BUT as I said everything still seems healthy...?

Should I be adding something else to the soil to counter something in the grinds...?

As this is my first vege patch I am of course like a new Dad and freaking out every time ANYTHING different happens :)

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Comments (3)

seysonn
11 years ago
I think that coffee grind is a good soil amendment and conditioner. The Nitrogen in it might not be readily available the first season but eventually it will be. However, coffee grind is slightly too acidic to most garden veggies. But in small amounts it should not make a significant difference, unless your soil is already overly acidic. It is possible that it might have other mineral supplement to, that I do not know of.

Seysonn
digdirt2
11 years ago
"Only a thin layer" is a subjective judgement and likely means different things to different people. And of course not all grounds are the same. :)

But in general, using coffee grounds is one of those things that can't hurt and might help down the road".

From your description of the new growth your plants are likely NOT responding to the coffee grounds but to something else like insufficient N, Coffee grounds just don't work that quickly. When you do see a change in the plants from coffee grounds it is usually a brief response unless they are used in excess. Keeping in mind that legumes (beans) do not require extra N like other plants do, some sort of more readily availble N source may be needed.

Dave
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daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
11 years ago
I'm not sure that coffee grounds are really acidic. Certainly not after they've been brewed. The roasted beans are acidic, but the acid is water soluble, so most of the acid ends up in the coffee. If you want to acidify a bed, you're probably better off pouring coffee on the bed rather than using grounds.

My understanding is that the grounds are actually abut 2% N. Not bad. So in a compost pile they work like "greens" even though they are brown. I have heard (I can't remember where) that uncomposted coffee grounds actually stunt growth, if used in large quantities (as in, 25% of mix). So although they have nitrogen, uncomposted coffree grounds don't release it in a very usable form. So if you use uncomposted coffee grounds as a soil amendment, don't use too much.

If you have a source for a lot of coffee grounds, get yourself a compost pile! I routinely use coffee grounds in my compost pile.