I believe my compost pile is now finished cooking, the piles been cold for about 6 weeks or so. Compost pile consists of nothing but coffee ground, 2-3 year old horse manure, leaves and grass. In the past I have added alfalfa pellets and molasses to help create and hot pile, now that the pile is cold I want to mix the compost with my humus potting soil for potting about 150 Japanese Red Maples ( Acer Palmatum Atropurpureum) This type of tree is known to have a sensitive root system and does not like wet feet. Should I just stick with the humus potting soil which drains well or if I mix the compost in would it give the roots a boost to help the trees thrive. I have never fertilized the trees at all and have been in raised beds for approx. 4-5 years, in the process of digging and potting some up.

Just a thought. Maybe do a sample group of ten with the compost mixed in then check and record the progress versus the others?

Less risk and good science

Good idea, I'll give that try. thanks for the response.

I would try to keep the soil the same in the pots and apply compost to the surface after potting.

We potted up about 10 of the Japanese Maples with the compost mix, still waiting for them to break dormancy. I'll try a few more with regular potting soil with compost on top. Thanks for the responses.