Here are some of my ideas reference your situation. Other colleagues may have other ideas.
In my opinion you could sprinkle / distribute your castings on your garden space right now / anytime. Spread out 1-3” of castings in your garden, then scratch them into the soil, about 3” deep with a tine rake. Then sprinkle with water. Then cover the whole amended area with 4” of organic mulch: leaves, straw, pine needles, shredded paper or a combination of those mulches. By doing this you put the castings to work in your soil. Yes, microbial activity in winter is slow, but come spring you’ll be ready for increased microbial activity in your already amended soil.
Storage of castings:
When you purchase worm casts or compost from a supplier, they are often quite dry. So, spread out the castings on newspaper or tarp to allow some evaporation of moisture. Once they are somewhat dry you may store them in paper bags or plastic bags which are punctured with small holes for some air intake. Dried castings will store for several months as decomposition will be very slow due to dryness.
For me an ideal storage container would be a homemade trash can bin. Pick a size which suits your needs. See this webpage, select “plastic container bin” at bottom:
If you store the castings at their current moisture level, then they may compact, thus reducing airflow, possibly becoming anaerobic, then unpleasantly odiferous. If you do choose to store them as moist as they are, then some of the residual eggs may hatch in the castings and you’ll have more worms! For moist storage, I’d suggest the above mentioned trash can bin, this method allows for some airflow in the
container. Worms are superfine !
Just some ideas for you. Best.
Please login or Register to submit your answer