Planting the forsythia
The best time to plant this shrub is in the autumn, then the plant has time to root properly until winter. The forsythia is a strong shrub which only needs watering in extreme heat and drought. Think of a period of 15-20 days. This shrub loves the sun and needs at least six hours of it every day in spring and summer. The forsythia is also easy to take cuttings from. Put a few young shoots in a pot of soil and if they catch on, they will root within a few weeks. A possible problem with the shrub is that it is susceptible to rot, which is caused by a bacterium. The leaves then turn brown and eventually even black. To save the forsythia, you then have to cut it back until you reach healthy wood.
When and how to prune the forsythia?
Pruning a forsythia is a tough job and if you are not sure, it is wise to watch an instruction video.
You should prune the forsythia after it has flowered in the spring. Flowering takes place on biennial wood. If you prune after flowering, the shrub has enough time to form new branches. Pruning goes as follows:
Look for a strong shoot on the dead branches that is growing outwards.
Use sharp pruning shears and cut off the rest of the branch at an angle, just above the spur.
Prune a number of old branches every year to just above the ground.
To get a richly flowering shrub in the following year, you should leave about 3 to 5 strong and healthy branches.
Dead wood and weak, thin side branches should be cut away. These only cost the bush unnecessary energy.
If the forsythia has not been pruned for a number of years, a normal pruning is no longer sufficient and you should do a rejuvenation pruning to nullify the effects of the neglect. In spring, three years in a row, you cut back about 1/3 of the branches. In this way you renew the bush in a period of 3 years. In this period you should also remove dead or damaged branches completely.
If you do not have time to prune in the spring, you can do so until June at the latest. Never prune a forsythia in winter, because then it will not flower the following year.