currently in Austin

the show

Time to Plant Trees

air date: October 26, 2013

Tree loss is at record numbers. April Rose from TreeFolks explains how drought impacts our trees over the long term, how we can help, and good choices for replacements. On tour in San Antonio’s historic King William district, visit a drought-tough makeover that started with tree renovation. Daphne explains how to properly mulch trees to avoid causing problems. Her pick of the week is Chinkapin oak, a trustworthy oak for smaller gardens.  Trisha brings fresh food to the table even if you can only grow in containers.

Question of the Week

Why is it bad to mulch a tree up its trunk?

This practice is widely known as “volcano-mulching,” and makes the space directly adjoining the trunk nice and attractive to insects and diseases.

Mulch helps to maintain moisture, but when over-watered, never dries out. This is especially problematic for newly planted trees, whose bark is relatively thin and easy to penetrate. And if the bark is damaged or rots away, it creates an easy pathway for invasion into the growing tissue.

This could slow the tree’s growth, or even kill it. Overly wet mulch also encourages roots to grow up into the moist area, rather than down, where they belong. In extreme cases, this can also encourage the roots to girdle, or grow in a circle, eventually choking the tree.

And in keeping with our tree-based theme this week, let’s talk about mulching. Since we see trees mulched all over town, we know it’s a good practice. But since it’s often done incorrectly, we may have learned the wrong way to do it. Mulch should be spread over the entire root zone of the tree, but not all the way up against the trunk.

I’m going to steal a pun from one of my colleagues: Problems ERUPT when trees are volcano mulched.Yes, yes, I know that was nerdy.

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Plant of the Week

Chinkapin Oak

Chinkapin Oak

Quercus muhlenbergii

If you're a frequent viewer of this show, and of course I hope that you are, you may have noticed that we highlight quite a few plants with the species name muhlenbergii. And that allows me to momentarily indulge my plant nerdiness and point out that the common practice of naming plants for the person who discovered them, or perhaps some other fabulous botanist that other fabulous botanists wish to honor. Well, Chinkapin oak was named for Gotthilf Heinrich Ernst Muhlenberg, an amateur botanist who lived in the early 19th century. Now, back to horticulture. Chinkapin oak, a Central Texas native, is a medium-sized tree, reaching 40 to 50 feet tall, and just as wide, in most landscapes. It's considered a moderately slow grower, but your patience will definitely be rewarded with a beautiful specimen tree. With a nice, rounded canopy and glossy, deep-green leaves, Chinkapin oak provides lots of shade, and is one of the rare native species to give us a bit of color in the fall. In the wild, it grows in well-drained soil, but easily adapts to a range of other soil types. And another great quality of this native tree is that it's rarely bothered by pests or diseases and requires very little pruning to achieve its very attractive, rounded shape. Like most other native species, it requires almost no supplemental irrigation once established, making it a very good choice for our area in these continuing dry times.