I don’t have a soil block so I put together a homemade version. And it works perfectly. In 17 days, or sooner, these will be ready to plant right into my sun box. After about 10 days they go right into the garden, where they will grow very quickly. What the difference between a sun box and a cold frame? A lot. I’ll be teaching a class on how to have the earliest spring garden possible in zone 6.