The main advantage of using flats is that more plants can fit into the same space if plants are in flats. However, if you start seeds in flats, you will need to transplant to larger cell packs or to individual pots as the seedlings get bigger. Seeding directly into cell packs saves time, because transplanting into a larger container later is not necessary. For tomatoes and peppers, 72-cell packs work well. Other types of containers include clay pots, plastic pots, peat pots, and compressed peat pellets.
Peat pots are containers of peat moss compressed into the shape of a pot.
These are convenient since the entire pot can be planted in the ground. This is an excellent system, since there is minimal root disturbance. However, peat pots are more expensive per unit than cell packs or flats. Peat pellets are compressed circles of peat that swell to form cylindrical containers when wetted. Seeds can be planted directly into a small hole in the top.