Gardening with Allen

Fall tree and shrub pruning

Question: I have shrubs which are blocking my windows and have grown over walkways. Is this a good time to prune them or should I wait until spring?

Answer: Except for spring flowering shrubs like rhododendron and azalea, this is an excellent time to prune. Spring flowering shrubs have already formed flower buds for next spring. Pruning now would remove many of those flowers. The best time to prune flowering shrubs is right after they bloom.

I prune almost all my shrubs one branch at a time. This keeps their natural shape and thickness. Pruning with power clippers or shears causes plants to develop many more branches than is normal. There are a few plants like hedges and upright conical junipers that look good with thick growth.

Start by selecting one of the longest branches and reach down inside other branches. Cut it a little shorter than the height you would like the shrub to be after pruning. Select another long branch and do the same with it.  The shorter adjacent branches hide the stubs.

In most cases shrubs should not be reduced in size by more than 1/3. Be careful not to prune evergreen shrubs like juniper and pine so that all the green growth is removed. Broad leaf shrubs can sometimes be pruned more than 1/3, but it may take more than one season for them to return to normal size.

Upper side branches should be shortened more than lower ones so you retain the natural tapered shape. If lower side branches are shortened too much, they become shaded by upper ones and eventually lose their leaves.

Trees can also be pruned now. Extra long branches can be shortened, just like shrubs. Lowest branches can be removed as the tree grows taller. When branches are removed completely, a ¼ inch stub should be left. This stub is referred to as a collar since it looks like a shirt collar. The collar contains the healing tissue which the tree uses to heal the wound.

Allen Wilson

Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture. Additional gardening information is available on his web site: naturalpruningnw.com under "how to guide". A monthly email garden newsletter can also be signed up for on this site or by sending a request to allenw98663@yahoo.com.

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