I get 5 gallon buckets of coffee grounds occasionally from a local coffee shop, and apply it right over the mulch in mixed beds, or add it to the compost pile (as a green material, even though it's brown).

The grounds apparently don't have the acidity that coffee itself (the beverage) has, so I'd be a little more concerned about pouring coffee on my plants than about using grounds.

I've read that worms love the stuff - I haven't checked whether coffee-treated areas of my gardens have more worms than other areas, though.

The down side(s): I love the smell of coffee, but the stuff in the buckets tends to smell, at first, like hideous (to me) hazelnut-vanilla flavoring. There are filters mixed in, semi-rotted, which are a pain to remove. The buckets are danged heavy - I wonder if the cost of free grounds plus chiropractor visits actually exceeds the alternative cost of bagged manure with no chiropractor needed.

Perfect for hydrangea, azaleas, any real acid loving plants.
Been using my coffee grinds around my blue hydrangeas for over 20 years and they love them, grow beautifully and are as blue as blue can be.
I just dump them around the plants on top of the mulch and just work it in a little.

see the pics below of the coffee loving hydrangeas I have

{{gwi:992903}}


{{gwi:992904}}

Fran

My indoor African Violets love some coffee every once in a while. I also save the grounds for my rhodies and azaleas. I haven't thought of using them on my hydrangeas, but why not.... If you have too much, you can definitely add the grounds to your compost bin too. All in all, there's no reason why coffee should be going into the trash!

For years and years my mother, who passed away last yr. at the age of 90, saved her coffee grounds and added them to her mulch pile and/or directly onto the soil in her flower beds. I'll tell you folks... the dirt in her garden was dark black, soft, and loaded with worms, so she must have been doing something right.
Molie

Hey littleonefb That is one beautiful hydrangea! Can you tell me more about it? I live near Boston and I would love to add a hydrangea to my (small) yard.

I will try the coffee grounds!

I've been working them into a couple of areas of my gardens, but now that you're all suggesting these uses...well, my hydrangeas & rhodies will get a dose asap!

Last summer I started getting buckets-full from a local coffee/doughnut shop. I've been using them to build lasagna beds. I also get occassional buckets from a local store, but since these tend to be kind of sour-smelling (I think they sit for awhile before they get to me) I put these directly in the compost pile.

:)
Dee

Seems that the argument for coffee grounds is pretty good--that Hydrangea, Fran, is gorgeous!

I think I will keep dumping them out into the gardens. My plots are too small to go begging at a coffee shop, but, what a great recycling effort for those of you who do (injured backs aside...;)!
Emily

Thanks Mskee and Gfult for the compliments on the hydrangeas.
Gfult, I wish I could give you info on it. I don't know what kind it is. I purchased them around easter time 25 years ago at the local market. Planted them outside in the shade and was told they wouldn't come back because they where hothouse forced and wouldn't be hardy for New England zones. I was lucky as both of them have been there every year blooming like you saw. Except for 2 years ago when we had that bitter cold January and no snow protection. they didn't bloom that year.
The smaller one is a 3 year old from root cutings of one of the 2 original ones.
Some one on the hydrangea forum suggested it might be one called Mathilda Gutges. The pic looks like it but I can't be sure. I can tell you that the stems and new leaves come directly from the ground and new growth on old stems. Some of the old stems suffer winter kill and I remove them. The flowers bloom on the new growth from the ground and from new stems that come off old stems and on old stems too.
I prune them to keep them from getting to large because of where I have them planted. Also they are a very deep blue color and if you have too much light on your computer screen you may not be seeing how really deep blue they are.
I have never seen another hydrangea with this deep blue before I got these or since. they are acid lovers and the blue usually need at the very least, partial shade. These used to get almost all shade, but since I originally got them, many trees have been cut down so they get partial sun in the morning and then in the late afternoon, which has not affected their color.

Fran

Thanks Fran, I am on a mission now.
They are beautiful!

There is a misunderstanding being generated by this thread. Coffee is acidic and will lower the pH of your soil but this alone will not turn your hydrangeas blue. It's the aluminum in the soil that is responsible for this and only at an acidic soil pH will this element be available to your plant. So adding coffee to your soil will turn your hydrangeas blue only if there is enough aluminum in your soil. I would suggest measuring the pH of your soil with a pH meter available at most garden centers (and Home Depot). Most soils in New England are already acidic and really don't need treatment to make them more acidic. If your soil is already acidic then add some aluminum sulfate around your hydrangeas to make their blooms blue. If your soil is alkaline or neutral then do they coffee trick. You still may have to add aluminum depending on the color of flowers that you get.

Make sure you don't get coffee grounds into the center of the hydrangea - over its crown. Ants like it too and will swarm to build a nest there. I have one enormous hydrangea that I unfortunately - in my earlier days of experimentation tried that with. The result is a spreading hydrangea that put out a lot more stems but the very center was an anthill till I chased them off with cinnamon.

I have been using Starbucks coffee grounds, both in compost and directly on the garden. My beautiful purple 'Mathilda Gutges' hydrangea came up pink this year! I fear that the added nitrogen interfered with the acid balance of my soil--all my neighbors have purple and blue hydrangeas (and this one was purple last year). What can I do to gently return the hydrangea to subtle purple shadings--without pushing it all the way to blue? By the way--my info shows that coffee grounds do not acidify the soil; rather, they add nitrogen.

Hmm. Very interesting. If the coffee grounds were acidifying the soil, and if I have not lost all my marbles yet, the hydrangea would have gotten bluer, not more pink, so this seems to confirm previous posts.

Couple related points. My H. Preziosa is a completely different color than last year, and seems to be blooming much earlier. It's a light pink - last year it was a much deeper color and, if it went through a pale phase it went quickly, cause I didn't see it. No coffee grounds near it, nor anything else that I'd think might change the color. I wonder if the wet spring affected the colors we're seeing this season?

Old timers around here claim you can deepen the color of hydrangeas by adding old rusty bits of iron - not always the most charming thing to see under the shrubs, but I've done it with iron sash weights (not the lead ones) and that MAY have worked. Hard to compare color from one year to the next, isn't it? Anyway, that doesn't effect blue/red balance, it just makes them have a deeper tone to whatever color they are.

Please use caution if you decide to use aluminum sulfate per TO's post. I would not use it without considering potential harmful effects.

Aluminum sulfate and coagulants afflict the nervous system, liver and heart. - PubMed at NIH

Here is a link that might be useful: NIH pub med abstract