Whats the verdict with coffee grounds ?

I read somewhere that spent coffee grinds were good for plants and for keeping bugs away.  In the winter they keep going into the same beds.  Our compost pile is little more than barn scrapings and yard waste because most table scraps to to one of the critters.
 
Spent coffee grounds *in moderation* are OK, but you really are providing worm food and microbes. The grounds, themselves will just sit there and leach acidity, unless broken down by something else. It's OK to apply them in moderation, but unarguably, the best way to use grounds, is in compost or vermicompost. Even then, you have to be careful not to give the worms too much at a time.
 
One way to add coffee grounds to soil effectively is to do it over a month ahead of time (in warm weather, much longer in cold) and keep the soil damp yet aerated so it becomes its own compost system.

The acidity can be countered by things like (the average municipally treated, alkaline) tap water. The acid is water soluble, rinses away and what remains is just from inadequate extraction of coffee during brewing. In other words a fairly efficient coffee maker will produce nearly neutral pH grounds. It also reacts with whichever source of calcium carbonate you might wish to add, instead of having to buy commercially produced calcium salts.
 
I wouldnt use them on peppers or tomatoes, just compost... and BLUEBERRIES! (and hydrangeas if you want blue flowers, Im sure azaleas and rhododendrons would like it too)
 
I have "watered" my balcony plants with diluted cold coffee and they seem to do okay; the used coffee grounds are going into a front garden that has very heavy clay soil.
 
I also have some sprinkled on top of the soil of a potted plant that is sitting outside. Funny how slugs don't seem to be bothered by the coffe grounds as I can see their slimey trails on the soil surface in that pot. :mope:
 
People definitely should not be scared of coffee grounds... In my experience, you will have a hard time adding too many coffee grounds to your compost, worm farms, or garden.  I will repeat the story I have told a few times whenever "excessive coffee grounds" are brought up.  Before I ran any sort of worm farm, my aunt had given my brother a worm farm for Christmas.  Well, the way it turned out, my brother did not take care of the worm farm.  It was left to my dad to manage the 30 gallon tote with worms and a small bit of worm bedding while my brother and I were away at college.  Well... my dad had only been feeding these worms coffee grounds/filters.  He would simply lift the lid a little and slide a fresh filter/grounds into the bin.  By the time we got out of school, it had been 5 months of nothing but that diet for the worms.  After returning home for the summer, we pulled the worm farm out side and popped the lid fully open for the first time since he set up the tub.  Lo and behold, there was a writhing mass of worms that filled the entire bottom of the bin 3 inches thick. Amazingly, these worms had survived on nothing but a daily dose of coffee refuse.... and no bedding or extra water.  This is obviously not the best case scenario for worms, but it just goes to show how tough they are, and how harmless coffee grounds (used* coffee grounds). 
 
I feed my red wigglers my coffee grinds, and they feed my plants. I'm fairly sure the worm castings are more readily absorbed by the plants compared to the grinds.
 
Noah Yates said:
People definitely should not be scared of coffee grounds... In my experience, you will have a hard time adding too many coffee grounds to your compost, worm farms, or garden.  I will repeat the story I have told a few times whenever "excessive coffee grounds" are brought up.  Before I ran any sort of worm farm, my aunt had given my brother a worm farm for Christmas.  Well, the way it turned out, my brother did not take care of the worm farm.  It was left to my dad to manage the 30 gallon tote with worms and a small bit of worm bedding while my brother and I were away at college.  Well... my dad had only been feeding these worms coffee grounds/filters.  He would simply lift the lid a little and slide a fresh filter/grounds into the bin.  By the time we got out of school, it had been 5 months of nothing but that diet for the worms.  After returning home for the summer, we pulled the worm farm out side and popped the lid fully open for the first time since he set up the tub.  Lo and behold, there was a writhing mass of worms that filled the entire bottom of the bin 3 inches thick. Amazingly, these worms had survived on nothing but a daily dose of coffee refuse.... and no bedding or extra water.  This is obviously not the best case scenario for worms, but it just goes to show how tough they are, and how harmless coffee grounds (used* coffee grounds). 
Click to expand...
 
So, me pouring about 4-5 gallons worth of grounds on a 100 sq ft plot is safe?  So far I have not seen any negative repercussions from it.
 
I would think that is a safe ratio... the more coffee grounds you can acquire the better.  If you start to notice a problem with pH then a little dolomite will help to raise the pH... and some supplementary gypsum will help to keep it dynamically stable.  Honestly, I would recommend applying gypsum and dolomite (sparingly) in any case.  
 
The benefit you receive from using coffee grounds will be directly proportional to the productivity of your soil web.  A healthy soil will quickly colonize and compost the grounds in situ... so long as they remain moist.  As has been mentioned, the nutrient content of coffee grounds can be made available more quickly when composted or fed to worms before making their way to the garden.
 
Also... I want to clarify that when we speak of coffee grounds in a horticultural setting we are talking about *used coffee grounds... pre-leached with boiling hot water.
 
I look to compost several hundred pounds of coffee grounds over the next year.  It is a good nitrogen source.  I would only advise using it as a main component of compost if you have sufficient carbon going into your compost pile (Dead leaves).  
 
the coffee grounds help me get that "crumbly" effect everyone is always going on and on about.  
 
 
Starbucks "Grounds for Gardens" program is wonderful.  I stop by 4 Starbucks on my way home each day and I get around ~40 pounds of spent grounds every afternoon.  I combine the grounds with weeds and dead leaves.   I use the high nitrogen grounds to get a hot compost going to kill off my garden's weeds.  
 
 
Think of the soil as a giant stomach of the earth.   Eventually everything is eaten.  Unless you are using a ridiculous amount of coffee as a top dressing the PH will never change enough to matter.  
 
Oh fun fact about "Acidic" compostables.   When pine needles are brown, they are PH neutral.  So you can safely compost them when they are chopped up.  
 
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