I agree with Millet. Organic fertilizers are good during the hot season, when you can add microorganisms from compost tea, vermicompost or supplements. Liquid humic acid and humus works well. But here there is another catch, these can also contain bad microorganisms in a low amount not harmful to plants. Still when the plant is stressed or soil is overwatered and cold these will take over. So instance Phytophthora.
If one applies in the winter, the fertilizer won't decompose so fast with the help of beneficial microorganisms. In fact anaerobic bacteria, mold and algae will take over which could in turn lead to root rot, and the soil becomes mushy. for those who don't believe apply organic fertilizer pellets on top of the soil, and put it in greenhouse at 10C or 50F and 90%RH, a white crust of mold will start to grow on top.