50℉ is a good temp for nematodes and the kill can be 100% effective a virtual knock down at this temperature. In the basement put a seedling heating mat under the pots your treating with bacteria whether insecticidal or symbionts. Your current 50℉ temp will make them drowsy and want to hibernate.
The basement is a perpetual Fall temp soil, a good time to apply outside too in the Fall.
Bacterial applications work better in warmer soil. Many will not be effective until the air temp is consistently in the mid 80s. Many bacterial recommendations are made way too early in the season when the soil is still too cold and they will not be effective.
Bacterial products are on the shelves for the Spring planting madness for purposes of commerce more than anything else. That is why multiple applications are recommended. Selling more bacterial products but Unfortunately being used too early the bacterial product gets a track record they do not deserve. Encouraging people to choose less effective but more toxic chemical pesticide alternatives.
Multiple applications can be a flag for products that are ineffective from the start, usually from adaptive resistance and chemical remediation by the insects symbiont bacteria to the applied pesticide toxins.
Being informed and getting working experience with the biology of the all the organisms involved is fundamental to increasing the abundance of best recommendations.
Best time to apply bacteria after a week of mid 80℉ and at the end of the day and before a rain, a bonus if you can swing it, is a good measure for bacterial applications. Warm your water like you do for sourdough. With Bacteria a pinch is as good as a pound, you don't have to use a fire hose mounted on a 50 gallon drum.
