When plants get too large for their spot or pot, divide or separate them into several smaller plants. Division is an easy and cost-effective way to propagate plants. Water the plant well before dividing and make sure that each piece has a root system, to allow new divisions to grow. The best time to divide plants is when they are dormant; so divide spring- and summer-blooming ones int he autumn, and fall-blooming plants in spring. Houseplants should be divided in spring before they put out new growth. For tubers and bulbs, divide them before planting in the spring.