Tomato plants prefer acid soil. Adding used coffee grounds helps increase the acidity of the soil.
That is great news since I recently followed up another tip that I reported on in the spring: Starbucks provides the gardener with free coffee grounds. Read all the Starbucks coffee for Gardens info here.
That’s right- I went to Starbucks and they gave me a bunch of coffee grounds! I was so excited. I usually only have the pittance from my own coffee maker that goes into the compost pile, but now a whole bagfull to dig directly into my garden:)