Friday, November 1, 2019

It's Arbor Day in Texas!

Collin McMichael, of Treefolks, demonstrates the proper way to plant a tree.
Photo by Caroline Homer, Travis County Master Gardener.

There is a reason that Texas has designated the first Friday of November as “Texas Arbor Day”. Trees planted on National Arbor Day in April have a tough time surviving our hot summers, which is why Texas Arbor Day occurs during cooler, more favorable conditions. With shorter day lengths, cooler temperatures and maybe even a little rainfall, autumn has everything that a tree needs to keep transplant stress to a minimum.

Most of the trees that we plant here in central Texas are deciduous so they will soon be dropping all their leaves and going dormant to avoid the damaging cold of winter. During the winter with no growth happening above ground, trees are free to focus their resources below ground on their roots. If planted in the fall, trees have almost half a year to establish their root systems before the temperatures get overbearingly hot and they start to need more water to survive.

In order to take up water, plants must release water into the environment through a process called transpiration. During the heat of summer, the air is so hot and dry that it practically sucks the water right out of the leaves, which is why during extremely hot weather like we had in August and September of this year, many trees dropped their leaves and went dormant. Dormancy is simply a plant’s way of avoiding stress. It takes a lot of water to support a canopy full of leaves, and if there isn’t enough water, which is a pretty stressful situation, a good strategy is to drop those leaves and go to sleep until the stress passes. We’ve received a lot of calls these past few weeks about trees losing their leaves early and struggling through the summer. However, I bet now that the temperatures have begun to drop and the sun becomes less intense, those trees may take advantage of that short autumn window to get just a little bit of growth before winter and its true dormant season arrives.

The lower temperature and higher relative humidity of fall help to keep trees better hydrated, so planting during autumn gives trees more time to acclimate to their new environment in your yard and get established.

If you’re still deciding what type of tree to plant, here are two resources you can utilize. The first is the tree selector tool on the Texas A&M Forest Service site. The second is the Earth-Kind® plant sector database. Some of my favorite trees like Catclaw Acacia, Cedar Elm, and Lacey Oak are in the Region-F- Hill Country & Central Coast list. 
And check out our throw-back Texas Arbor Day video on Central Texas Gardener, too!

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