Starting plants from seeds is quick and easy when you start with the Jiffy Pellet Greenhouse. This kit includes 12 peat moss pellets that expand to provide both the pot and soil you need for your seeds to germinate successfully. Place the clear dome on top to retain moisture and create a greenhouse effect for your new plants. Dimensions: 10.8L x 4.8W x 2.2H in.. Pellets expand, forming pot and soil. Pellets made from sphagnum peat moss,. Great for starting flower and vegetable seeds. Grows 12 plants. Plastic dome retains heat and moisture.