Perennial: Monarch Butterflies only lay eggs on plants in the milkweed family and these plants are the only food the March Caterpillars eat. Milkweed grows 60-120 cm tall (2-4′). Mature seeds from the plant are distributed by the wind. Sowing: Direct sow late fall or spring after danger of frost has past. Choose a sunny site and cover seed lightly with water. Seed can be started early indoors in February, by using a soilless medium and placing the container in the refrigerator for 3 months. Bring the container out and keep at 20C (70F) for the 10-18 day germination period. Keep under lights at a cooler temperature then harden off and transplant outdoors after any change of frost. Comments: Sap is poisonous if ingested by humans or livestock. Approx. 40 sds/pkt.