I have had my worms in two wood containers for about five months. But during the last month or so, I have had to put a heat source under the bins for the coldest nights, to prevent freezing. Naturally, I have had to give more water sprays to prevent any drying action. But I have noticed some of the bottom parts of the bins, which are closest to the heat, the castings appear to have dried. Are those castings no longer of value if applied in my garden?