VitaVeggieMan wrote: I've used Jiffy pellets with good success, especially the larger tomato pellets. This year, the tomatoes I started in Jiffy Tomato pellets ended up being significantly larger than those I started in smaller plastic cell packs, even though I potted both of them up into the same size 12 oz. plastic solo cups (see picture). The peppers in the Jiffy Tomato pellets were slightly larger, but not as much difference as with the tomatoes. And the Tomato pellets work great for cucumbers, squash, and snap beans as well, all of which can be transplanted to the garden within 2-3 weeks.
Since the pellets make planting seeds so quick and easy, I find I plant more seeds in a timely manner. You do have to remove the casings when planting outside as others have said, but I have not found a need to spread the roots. When I've potted them up to larger cups, the roots quickly expand to fill the cup. The peat pellets seem to be slightly more susceptible to damping off than coir pellets, but I've managed to control that by (1) removing the greenhouse cover as soon as seeds germinate, (2) bottom watering only, and sparingly, (3) adding 1/3 cup of hydrogen peroxide per gallon to the water, and (4) having a small fan running nearby to keep the air circulating at all times.