Boxwood turning brown #185876 - Ask Extension

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Boxwood turning brown #185876

Asked May 27, 2014, 8:22 PM EDT

Some of my boxwood are turning brown. Some completely, some just partial. We have an abundance of them in my community doing the same thing. Will they comeback? Or are they lost forever? I believe the type of Boxwood is Winter Gem. 

Livingston County Michigan

Expert Response

The key is have patience. I have the same problem with my boxwood. You may also be observing browning of leaves on other broadleaved evergreens such as azaleas, rhododendrons, hollies, grape-holly, euonymous and mountain laurel. (These plants, like boxwood, bear leaves that normally stay green all year.) This browning, also known as desiccation, occurs when winter winds draw moisture out of the plant tissue. Since the temperatures have been so extreme, these shallow-rooted plants cannot draw any more water from the frozen ground to replace the water lost by the leaves. You will especially see desiccation on the windward side of plants as the air draws moisture from the leaves as it passes by. If the roots cannot pull up any water, the water that transpired from the leaves cannot be replaced; therefore, these cells die causing brown tissue.
Once the snow melts, you can see the differences in shrubs or plants that were partially snow-covered. The portion of shrub that was covered in snow was insulated against the colder temperatures and wind, thus did not suffer as severe burn.
Will these plants survive? It depends on the severity of the damage. Be sure to wait until after shrubs leaf out if you are unsure whether or not a branch is still living. Check to see if there are any live buds. You don’t want to cut these off. Exposure to this winter’s extreme temperatures may have caused delay in leaf development on plants, so if you prune as early as you would after a normal winter, you may be cutting off live growth. The extreme temperatures that we’ve experienced may also cause buds and entire branches to die. Don’t be surprised if you also see some plants start to leaf out but then collapse. Corrective pruning along with recommended fertilization and proper watering will often help these plants recover.  
This is a good article from Missouri Botanical Garden: http://www.mobot.org/gardeninghelp/plantfinder/hortline.asp?code=3959
I hope this was helpful. Feel free to contact us again if you have further questions.
Ruth Simon Replied May 28, 2014, 8:49 AM EDT

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