Plant Starter Cell Packs Are The Best Way To Start Seeds. These cell packs keep the seedlings from getting their roots tangled. Each cell has drainage. Seedlings can be transplanted directly from these cells or repotted into peat pots or larger pots before being set out. For best results always use new cell packs, sterile seed starting mix and do not overwater when starting seedlings to avoid disease. These cell packs fit in the trays with and without drainage. 21" x 10.5" x 2.25". 12 6 packs. 72 cells.