How far can you trim back a boxwood?
I have a boxwood (not sure which species) that was already by my front porch 35 years ago when I moved in. It has always appeared healthy & has grown to over 5'X5'. Can I cut it back to about 3'X3' without killing it or making it vulnerable? if so, how long will it take to look OK again since the branches that far inside are brownish & barren now? If a major cut back like that is not advisable is there an amount that could be trimmed back safely? I assume the trim should try to keep the round shape of the boxwood, correct? Is early spring the right time to cut it back? Would any type of fertilizer help it return to normal more quickly? It is located in mostly sun, in Catonsville, with soil I do not know anything about. There are some daffodils & lilies at its base (& usually an annual or 2.) A yew is behind it (touching) and the porch & steps are on one side of it (also touching.) Thank you for any advice you can provide.
Baltimore County Maryland
There are several types of pruning methods for boxwoods - thinning, shearing, and heading back (restoring overgrown boxwood). You will have to decide on your goal. In general you should not remove any more than 1/4 of the shrub in a season. It would be okay to prune in March, early spring.
The best method for pruning English boxwoods is thinning. This allows the center of the plant to receive adequate sunlight and good air circulation. The best time to thin boxwoods is December through February. The temperature should be above freezing. http://www.usna.usda.gov/Gardens/faqs/BoxwoodThinning.html
Shearing - An example of this is if you are growing boxwood as a hedge. Best time to shear is in early June. A second light pruning may be needed in July.
If reducing in size drastically, this requires a two step approach and should be done in the early spring. If cutting only a small amount, prune at one time. First cut one half of all the large branches. The second year the remaining branches would be pruned in the same manner.
You can remove dead wood at any time.
Look at the American Boxwood Society for more information and fertilization
http://www.boxwoodsociety.org/abs_about.html#How do I know whether I should fertilize my boxwoods?