Coffee grounds on flower garden
You say to work the grounds into the soil. How far into the soil? Does it matter how much goes around the plant? Can I save grounds for a week and then use?
There is no good general rule, unfortunately... I can tell you what I do from experience. You can spend the time to work this into the top one or two inches of soil, or you can just spread them on top. Although they do provide a small amount of nitrogen, they are best used to break up soil that holds too much water. I use them to improve the texture of the soil, and not for the nutrient content. With this said... The best method is to mix it thoroughly throughout the entirety of the soil. This will give you the best results.
If you are trying to use coffee grounds for their nitrogen content, then the best way is to compost fresh, unused grounds. This will yield the largest amount of usable nitrogen.