Abstract: An improved, light-transmitting, plastic shelter cone or terrarium is provided for the germination of seed and growth of seedlings. The cone has a lower soil-engaging flange at its base and a vent opening at its top. The vent opening is covered with a hinged flap which is an integral part of the cone and to which seed may be secured using a water soluble adhesive. When placed in the field, the flap is pressed down into engagement with sidewall indentations which hold the flap and seed in a generally vertical orientation within the cone chamber. Stiffening ribs are formed in the cone wall, protruding outwardly and forming grooves within. Seed may be secured within a groove with water soluble adhesive. When the cone is used, rainfall will dissolve the adhesive, whereby the seed may drop to the soil below. Latching the flap ensures that it does not return to block the vent opening. Preferably, the plastic is sunlight degradable and is further colored translucent red to modify the transmitted light.