Older forsythia plants
We have two forsythia plants in our front yard that are at least 14 years old and probably much older. One is about 6 ft tall, and the other is 5 ft. They bloom very sparsely in the spring, and seem o.k. the remainder of the year. We have cleaned them out periodically, so that they now consist of a few long stalks with leaves at the top. We would prefer smaller plants with more dense blooms. Would it be advisable to cut them back severely in late fall?
Boulder County Colorado
Ideally forsythias are cut back after they bloom. Next years blossoms are generated through the summer and fall so if you cut them back this fall you will sacrifice your blossoms next Spring. I would wait but if you don't mind losing all the blooms you could rejuvenate the entire shrub. Here is some information about pruning forsythias.
Hope this helps!