When pruning crape myrtles, timing is critical to get best summer blooms
Q: What will happen if I prune my crape myrtles late? Marsha Franty, Houston
A: You’ll delay summer blooms if you prune after new growth has begun in spring.
There’s no set rule that we must prune crape myrtles. But, if it’s desired or needed, the ideal pruning time is late winter before the tree puts on new leaves. This allows you to better see the skeleton of the tree and determine which branches/stems need removing. Remove seed pods, unwanted pencil-size limbs and crossing branches that are damaging the bark and any dead wood.
Heavy pruning butchers the natural shape of the tree and discourages the best health. The whiplike new growth that emerges from newly cut, stump-like limbs is weak and easily snaps off in heavy winds. Drastic cutting also can prompt excessive growth at the expense of blooms. Branches also form unattractive, gnarly knuckles in response to the severe cuts.
Q: My lespedeza are blooming this spring, which they’ve never done. Do I
need to cut them back in order to have blooms in fall? Dave Sherron, Houston
A: While ‘Little Volcano’ lespedeza is known for its late summer-fall blooms, it also may flower in spring. The cultivar name is somewhat misleading as the plant can reach 6-8 feet tall and as many or more feet wide.
Lespedeza flowers on new wood, and many gardeners prune this large shrub rather hard in late winter and in early fall enjoy a large fountain of arching branches covered in rosy-purple blooms.
But many experts also prune after a spring flowering to shape a plant, trimming branches back a quarter or third. Remove any old, tired branches. The plant will put on new lush growth through the summer and sport future blooms when days begin to shorten.
Q: How cold-hardy is giant milkweed? Marilyn Blasingame, Houston
A: It is often roothardy in Zone 9 and farther south. I thought mine had been killed by the extended hard freeze in January, but eventually, new growth appeared. Heidi Sheesley of Treesearch Farms recommends a good blanket of pine needles around the root zone and even partially up the base of the plant for freeze protection.
Butterfly gardeners provide milkweed as host and nectar plants for monarch butterflies. Most often we’ve planted members of the Asclepias genus: native A. tuberosa, commonly called butterflyweed, with fiery orangered blooms; orange and yellow Mexican or tropical milkweed A. curassivica; and occasionally showy milkweed, A. speciosa, a native with blue-green velvety leaves and spherical clusters of star-shaped, rose-colored blooms.
The mother butterfly drinks nectar from the milkweed flowers and lays her eggs on the leaves. When the yellow, white and black caterpillars hatch, they consume the plant foliage, then crawl off and form their chrysalises. Later, a new monarch emerges — educational fun for the entire family to enjoy.
Giant milkweed, Calotropis gigantea, is being added to local gardens as a host plant. This attractive large, shrubby member of the milkweed family is native to India and southern China and cultivated in tropical areas around the world. It potentially reaches 8-plus feet; has slightly fuzzy, large, bold leaves; and crownlike white-lavender flowers.
C. procera, aka sodom apple milkweed and milkweed tree, has maroon and white flowers and velvety silver-gray foliage.