Master gardener on summer pruning

Get ready to prune. Late summer is the best time to prune maple, birch, beech, poplar, elm and willow trees. In the spring, sap is flowing from the roots, up the trunk and into the ends of branches to allow leaves to grow. These trees can be heavy "bleeders" in the spring. Some years, this is not a problem. But, if the autumn and winter have been dry, and trees are drought-stressed, bleeding can weaken a tree. In addition, these trees are prone to diseases that are more readily spread in the spring than in late summer or fall.

Evergreens, including juniper, pine and spruce, can be pruned throughout the year, but it certainly is more comfortable to prune them when it is cooler and long sleeves can protect your arms. Also, late summer pruning is less likely to stimulate new growth in evergreens. However, this does not hold true for all plants, and new growth on many plants is very susceptible to freeze damage.

This is why we don't prune roses during this time of year. I generally recommend leaving spent rose flowers on the plants now, and letting them turn into rose hips. This signals to the rose bushes that winter is on its way, and it's time to shut down in preparation. Around tax time, April 15, is the best time to prune roses. Of course, if a rose bush has branches sticking you as you walk by, go ahead and cut those branches out. Be sure to seal the canes with white glue to prevent borers.

Prune summer-flowering shrubs, such as Rose-of-Sharon, now, but do not prune spring-flowering shrubs at this time. Spring-flowering shrubs, such as lilac, bloom on last spring's wood. Cutting them back at this time will cut off all of next spring's blooms. In addition to late freezes, pruning at the wrong time of year is a major cause of lilacs failing to bloom.

Wait on fruit tree pruning too. Late winter to early spring is the traditional time to prune these trees. I prune when I can see the branch structure easily, but when the branches aren't completely frozen. Some gardeners prune their berry bushes now and others swear by spring pruning. It depends on the type of berry.

Whenever you prune, use sharp tools and ones that are the right size for the job at hand. Disinfect the tools with bleach and water or alcohol before moving to another plant. On poplars, elms and willows, disinfect between cuts on the same tree to avoid spreading diseases such as wetwood or cytosphora from limb to limb. Wear safety goggles, gloves and a good hat. Only prune what you can safely reach. Big jobs may require professional help.

Enjoy the last days of summer.

For more information on gardening, contact me, 887-2252 or, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at "Ask a Master Gardener" by e-mailing

-- JoAnne Skelly is the Carson City/Storey County Extension Educator for University of

Nevada Cooperative Extension.


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