You can grow Forsythia as a single shrub for a focal point in spring, or in a shrub border, on a bank against a wall. This shrub is also useful for hedging. It is a full hardy plant, that will survive outside over winter and will come back to life in early spring to show its flowers.
Forsythia likes a moderately fertile, moist but well-drained soil, in full sun or light dapped shade considering that around 6 hours of sun per day is the necessary for this plant.
You can easily propagate Forsythia by rooting greenwood cuttings in late spring or early summer, or semi-ripe cuttings in late summer. You can also try layering some branches. This shrub need pruning just after flowering period, not too hard to not encourage strong branches to appear because those are not going to wear flower in the next season. You just have to cut the part that was just wearing flowers.
In winter you will prune the branches that are too dense, the dead ones or the weak ones. Keep all the young offshoots that appeared after the pruning that you did after flowering, because those are the ones that will bear flowers next spring.
If you plan to plant a new Forsythia in your garden, late autumn is the best time for this, because the soil is still warm and moist and the shrub is starting its dormant period so the disturbance will not be so severe.