Richard

When applied to the surface, the worm flem in the castings attracts beneficial bacteria that has a lot of positive effects in the local environment. However, I have seen disastrous results from putting down worm castings and then a wind comes along scattering invading weed seeds throughout. IF you apply worm castings to the surface THEN you should mix them into your existing mulch. If you don't have mulch, then put down the worm castings and then add mulch on top. Somewhere else on this site I posted results from Ag tests run here in San Diego. As a top cover: a cured mulch alone is just as good as worm castings alone, but the combination is better.

Jack, from your earlier post it sounded like you were using pure wormcastings for seed germination. Now the 50/50 mix with horticultural sand sounds much better -- the castings are too dense alone.

__________________
Back in business at plantsthatproduce.com