How to Grow Forsythia:
Fast growing Forsythia bushes are easy to grow. Established plants require little , or no care. Grow Forsythia plants in full sun to partial shade. They will grow well in most soils. Soil should be well drained.
Water plants during extended dry periods as needed. Fertilize plants once a year in early spring. Use a high phosphorous fertilizer to promote bright blooms.
Flowers form on prior year's growth, not new growth. So, it's important to prune them immediately after the flowers have bloomed. You can cut back old growth to about about four inches from the ground.
Don't hesitate to be aggressive in pruning these fast growing plants. They will grow back at a fast rate.
Cutting Forsythia for Inside Florals:
Using sharp, clean pruners, give each branch a fresh cut at the base of the stem. An old way to encourage water flow was to smash the stem end with a hammer, but a better method is to make a vertical slit or two up into the end of each stem. This allows water to reach the swelling buds, ensuring big, happy flowers.
Place fresh cut stems immediately into a bucket of warm water with 1 tablespoon of bacteria-banishing bleach and a packet of cut-flower food. Keep branches in a cool spot - 50 to 60 degrees - out of direct sun, and midst frequently.
Forcing Indoor Blooms:
Forcing Forsythia to bloom indoors is a snap. Simply cut off a few branches, and bring them indoors. Put them in a vase with water. A couple weeks later, the branches will burst into bright cheerful, golden yellow blooms, right in the dead of winter.