My forsythia, which blooms very well every year, has gone somewhat wild and what I’d like to do now is to cut it back, right back down to about a foot off the ground. I’d like to know how long it would take to come back and can I do this now.
Forsythia is a vigorous grower, when left alone it can easily run wild. When the flowers have gone, for the rest of the year these shrubs can look untidy. So its understandable that you want to control the growth of your bush. Cutting it right back to a foot off the ground is probably a bit drastic. If you choose to cut it right back it would be preferable to do it before winter really sets in but it will mean sacrificing next seasons flowers. Forsythia blooms on “old wood” or last seasons growth which means that next seasons flower buds have already been formed. By pruning now you would be cutting off those flower buds, hence no flowers next spring. However, new stems will eventually appear and the shrub will re-bloom.
Forsythias respond well to regular pruning and the experts say that this is best done after blooming in late spring and before the leaves are fully open. Then you can see what you are doing. Shorten stems that have flowered by one third to one half, if you want to restrict your shrubs size. Cut back any older, thicker branches to the base as well as branches that are crossing each other. Cut out any dead, damaged or weakened branches. Never cut out more than one third of the bush you are pruning. If you want to have some blooms next year this is a much better option.
Bear in mind that all cuts should be made with sharp, sterile blades and it’s best not to prune when its raining or the weather is damp.
There is a ton of information on the Internet with regard to pruning shrubs, complete with diagrams of where to make cuts etc. A sample is listed below.