I pass several smaller hobby gardens on my way to work, and they all have two things in common: their owners are all definitely advanced in the “grey hair zone”, and they all applied horse manure to their winter leek in January. At first, I thought this was to fertilize the soil, but apparently, this is not the prime reason. It rather serves to increase soil temperature, so that at freezing temperature the leek can still be (easily) removed from the soil. Is this is a “Standard Operating Procedure” from older times, or still very current?