Don't murder the crape myrtles when pruning

Photo: Dave Bowman, MBR An improperly pruned crape myrtle produces a proliferation of thin...

Q: It pains me to see so many crape myrtles chopped down to ugly stubs. I see it everywhere, with properly pruned myrtles almost outnumbered by crape "murdered" trees. Will you provide pruning advice?

Betty Pritchett, Houston

A: The annual "crape myrtle murder" discussion has begun, so here are guidelines to prune these low-maintenance flowering trees.

Crapes do not need to be pruned to bloom. However, a tree can benefit from late-winter pruning to remove dead, weak or crossing branches and suckers at the base. But avoid mutilation.

Trim to maintain or restore a natural shape. Remove branches 2 inches or less in diameter, if necessary. Don't top the trees. This not only creates an ugly, stubby shape, it encourages vigorous but weak growth. Topped trees will always look ugly unless they're pruned to the ground so new trunks can replace the stubs.

Some resort to heavy pruning because the variety is too tall for the site. If a tree is just a bit too tall for the site, prune the top branches back 2 feet to a side branch. But don't leave stubs.

Crape varieties vary from 3 to 20 feet. Avoid heavy pruning chores by planting the appropriate size in a sunny, well-draining spot.

To improve the appearance of a once heavily pruned tree that has "knuckles," those knobby growths formed when a large branch is chopped, prune all but the straightest of the small branches emerging from the knuckle. This straight branch should line up with the large part of the branch below the knuckle. As the fingerlike branch gradually thickens, the knobby joint will become less noticeable.

To encourage more flowers, remove seed pods that develop after a stem blooms in late spring/summer.

Q: I like our two big live oak trees, but I especially like oaks that lose their leaves in the fall, like those I'm used to from living up North years ago. I recently scooped up some acorns dropped by a deciduous oak. I might try to plant one or two in containers and then replant later in the ground. How should I position the acorn when planting it? There is a top and a pointed bottom. Can you tell me which end I should have at the top?

Craig Power, Houston

A: Place the acorns on their sides when planting. I asked Adam Black, horticulture director at Peckerwood Garden, to share his expertise in growing oaks from acorns. Black oversees the extensive Mexican, Asian and native oak collections at Peckerwood, 20559 FM 359, Hempstead. See peckerwoodgarden.org for opportunities to explore this diverse landscape.

Acorns are ready for harvest and sowing when they easily separate from their caps, Black says. Collect harvest-ready acorns directly off the tree or as soon as they fall from the tree, he says.

"Our native and cultivated oaks ripen as early as September or as late as December," Black says. "Most acorns that have been sitting on the ground for extended periods will not be viable, as they can dry out rather quickly, and many get infested with insects. Acorns that float in a cup of water are dead and should be discarded; plant only those that sink to the bottom."

It's best to plant acorns immediately after collecting, he adds. However, if they need to be stored for a short period, store dry in a plastic resealable bag to prevent moisture loss from within the seed. Blot dry the acorns after the float/sink test to help avoid excess moisture in the bag as this or any condensation that develops can lead to mold.

"Some oaks, especially those in the white oak group (live oaks, white oak, burr oak, Monterrey oak) will germinate very quickly, sometimes in the refrigerator if not planted within a few weeks after collection. The red oak group (Shumard oak, blackjack oak, water oak, Southern red oak), will usually remain dormant for a few months, germinating in January to February in our area," Black says.

It is best to start seeds in pots rather than directly in the ground, he adds. A pot should be at least 12 inches deep to allow for an unhindered vertical tap root to form, resulting in a more vigorous seedling.

Sow one acorn per pot, or plant multiple acorns in the same pot and carefully separate the seedlings later. He recommends a well-draining, well-aerated chunky potting media of composted bark over peat-based commercial mixes.

Place each acorn on its side and bury with no more than a half-inch of potting media. Keep planted pots in the shade out of the wind, protected from hard freezes, and keep the soil evenly moist.

"Squirrels, mice and other rodents will quickly find them, and I have had determined squirrels gnaw through plastic mesh coverings, so metal hardware cloth may be necessary," Black says.

Upon germination, an acorn will first send down a vertical tap root and a short time later send up a stem with the first leaves. After threat of a freeze, gradually adjust the potted seedling(s) to increased light.

"Though they may only be 1-2 feet tall by fall, more vigorous trees will result if small yearling trees are planted in the ground during fall/early winter as opposed to keeping them in pots until much larger," he advises.

Q: When's the best time to order and plant caladiums? Do you have a recommendation for purchasing, either locally or on the internet?

Greg Armstrong, Houston

A: Houston-area gardeners use Easter as a reminder that it's caladium planting time. Ideally, the soil temperature should be around 70 degrees. Cover the tubers with an inch of slightly acidic, loose, well-draining soil. Plant with the smooth side down. Add a little sharp sand to improve drainage if necessary. Mix a little bone meal or superphosphate in the soil around each tuber. Use superphosphate if squirrels have a tendency to dig in your beds.

Generally, strapleaf caladiums tolerate more sun; fancy-leaf types want some shade. To promote more of the colorful foliage, remove the flowers as they appear. Keep the soil moist through the summer.

Ask your nurseryman about tuber availability. Watch for plant club/organization sales, such as that at quailvalleygardenclub.org/caladium-sale.