Coffee grounds mulch

Asked September 9, 2018, 1:36 PM EDT

Hello - This year I used coffee grounds as mulch around my dahlia bed, and it was surprisingly successful at keeping down the weeds and it looks nice too. Now that the season is ending I wonder what to do. Can I keep the grounds in place or should I rake it away? Can I turn the soil and work in the coffee grounds?

Multnomah County Oregon

1 Response

Hi, and thank you for contacting Ask an Expert in regards to using used coffee grounds as a soil amendment for your dahlias.

I would add the spent grounds to the soil around the plants at the base and work them into the soil. They would break down as any other organic material and add some structure to the soil. You also may get a slight bump from the tiny amount of nitrogen, phosphorus, and potassium in the decomposing coffee grounds.

However, remember not to till in too much as it can compact the soil and reduce oxygen to your plants a general recommendation would be at a rate of 10 pounds (dry weight) per 1000 square feet would be conservative.

Happy Gardening and again, thank you for contacting Cooperative Extension Ask an Expert.