Your grow kit just gave you a great harvest. Before you toss the block, know that it usually has more to give. Here are the best ways to get extra value out of a used mushroom grow kit, plus when it is time to let it go.
1. Go for Another Flush
Most ready-to-fruit kits produce two or three flushes, not one. Each flush uses up water, so the key is rehydrating the block. After harvesting, let it rest for about a week. Then submerge it in clean, cold water for several hours to overnight, drain it well, and put it back in the same fruiting conditions. Expect each new flush to be a little smaller than the last.
Growing in a monotub? The same idea applies, and our guide to dunking a bulk grow walks through rehydrating a tub between flushes.
2. Check for Contamination First
Before you reuse anything, look the block over. Patches of green, black, gray or pink mold, or a sour smell, mean the block is done. Do not open a contaminated bag indoors. Seal it in a trash bag and take it straight outside so spores do not spread to your next grow.
3. Plant It Outside
A spent block that is still clean and white is full of living mycelium. Break it up and bury it in a shady garden bed of moist hardwood chips or straw. Wood-loving species like oysters are the most likely to take hold, and with good moisture you may see surprise mushrooms in the spring or fall. Results vary, so think of this as a bonus rather than a sure thing.
4. Feed Your Garden
Spent mushroom substrate is loaded with organic matter. Crumble it up and use it as mulch around plants, work it into garden beds, or add it to your compost pile. It helps soil hold moisture and adds organic material as it breaks down.
5. Start Your Next Grow
Once a kit is finished, the best thing to do with it is use what you learned on the next one. Try a new species from our gourmet grow kits, or take the next step and grow from start to finish with an all-in-one grow bag and your choice of liquid culture.
What Not to Do
Do not try to reuse the bag itself for a new grow. Grow bags and their filter patches are made for a single sterilization and use. And do not keep a spent block sitting around indoors. Old substrate is an easy target for mold and fungus gnats.