I would think the coffee would gradually raise the acidity of the soil, which could be bad, depending on the plant.

An occassional cup shouldn't hurt anything, but I can't see how it helps the plant, either.

Out of curiosity, why do you do it?

If you use either, dilute with water. I've even use Coke on some, but not much and not often

I just started with the juice one day because I had a bunch left over from breakfast and couldn't bear to just dump it down the drain when I know there are nutrients in it (beneficial to plants I don't know) so I thought I would water my plants with it as they needed watering anyway, and I often eend up with juice that is getting old and so I was wondering if this is goood to do neutral of bad.
As for the coffee, haven't tried it yet because I was not sure which plants would like the acidity, I just read on one of the posts that African violets like coffee. Anyone else tried this??

My mother always watered her African violets with tea. (Actually, she dumped her used tea bags in a container until it was full, then added water and let it stew for a day or so.)

My understanding with coffee is the same as rain1950 - definitely dilute it with water.

This is supposedly a list of "houseplants" that like acid (I put that in quote marks because I do not consider all of these houseplants): African violet, aloe, amaryllis, Norfolk Island pine, azalea, begonia, bromeliads, caladium, cyclamen, dieffenbachia, gardenia, gladiolus, hyacinth, hydrangea, impatiens, iris, peperomia, phalaenopsis orchid.

My Mum waters plants with her old coffee, probably diluted. Her plants are always healthy looking, so it must be okay, she has done it for decades. I water houseplants with the rinse water from the blender after making my fruit smoothie. I figure it is like fertilizer, tiny little bits of organic material. Just dilute the juice, and hopefully it isn't all orange or grapefruit or something really acidic. Of course, as a frugal person, I am wondering why you can't just refrigerate your breakfast juice and drink it later. :-)

I also save the water in the shower into a container, the stuff that comes out before it comes out warm. I then water plants with it. I used to make fun of my mother for doing that, but now I do it, too.

Marcia

I work in an office, and everybody dumps their remaining coffee into the plants, with no diluting. Some of the plants are tropical plants, and they are all very healthy. Probably just a hit or miss situation.

i haven't done the diluted-coffee thing; what i've been doing is using water in which i cooked/steamed veggies (no salt), then using that for plants (inside & out)...after it's cool, of course. i figured it couldn't hurt them.

imagine my delight to find good ol' paul james recommending that very thing! ha-ha!

Watering house plants with either tea or coffee isn't usually a problem, the problem with using anything "extra" is the possible sugar content. The plants themselves don't mind a little sugar, but it does attract all sorts of visitors... from benificial bacterias to molds, fungus, ants, gnats, etc. Most of the unwanteds will feed on the baby feeder root systems of your plants. By the time the plant actually shows signs, and you've tried compensating for other possiblities (light changes, overwatering, underwatering, fertilizing, etc.) you may have lost him or her. Speaking from way too many "helpful" people adding to the plants I care for in offices and interiorscape atriums, but who never understand how come the unwanted visitors are always around their area only.

I use the water from my steamed veggies on my plants, they are all doing quite well. The one that especially seems to "love" it is my asparagus fern. After placing a post on the house plant forum, I learned the trick of the trade has been around for hundreds of years. Some say not to use water from the stinky vegs (broccoli, cauliflower, etc) but I do, they smell a little when you get right up to the plant but don't fill the room, also some say not to salt the water, I do and haven't seen adverse results.

I watered a Norfolk pine @ work one time with Coke, several actually (plants) - they all died.

That being said - i do take my leftover coffee (in the pot) outside to water my plants - i either put it in the potted plants on deck, or in one of the beds. Haven't tried that with juice or anything though...i figure the sugar would attract more ants...and i have plenty as it is.