I used them about 20 years ago when I started my seedlings in the basement under lights. They work. A bit of extra work and you need to figure out the correct moisture content for your dirt. Not hard. They fall apart easily when watering; its best to water from the bottom up. I prefered making paper pots out of brown paper. Tear paper into strips for the size pot you need and tape the ends together. Fill with dirt by setting them in trays together. They are moldable so no wasted space. Pop paper and all into the ground. If I were to use soil blockers again, I would go with the small blocker for the first stage of sprouting and then transplant into the paper pots. I found it to be a pain getting the little blocks into the big blocks. Just depends on what you are planting and how many times you need to transplant them. Tomatoes for instance do better when transplanted several times plucking all but the top leaves off and burying the stem each time.