Narrow-leaved sunflower Helianthus angustifolius
Garden columnist Dan Gill answers readers’ questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu.
I want to get a wisteria next spring. Is there a species that is not invasive? And will it hurt a tree to let it climb the tree? — Terri Troxclair
The most popular wisteria for planting is the Chinese wisteria (Wisteria sinensis). This vine is exquisitely beautiful when it blooms for a few weeks in the spring. But it is a rampant, even aggressive-growing vine that must be managed carefully.
It requires regular pruning and training and is certainly not for the casual gardener. In addition, it can escape into the wild, where its rampant growth is a problem.
But we have a perfectly beautiful native species — American wisteria (Wisteria frutescens). It is a less vigorous-growing vine that is far easier to manage. The dangling clusters of lavender flowers are not as long as the Chinese species, but they still put on quite a show.
Flowering is in late spring, around April or May. Amethyst Falls is a nice selection with large flower clusters.
Because wisteria vines are sun-loving and can cover the tree’s canopy, and because the vines will wrap their stems around branches and girdle them, wisteria vines should generally not be allowed to grow in trees.
Is there a preemergence herbicide for lawns that I can put out now to prevent the early spring weeds? — Nancy Smith
Yes, there are preemergence herbicides or weed preventers that you can apply now to prevent the growth of many common cool-season weeds. This should have been done back in early October, but an application now will still provide benefits.
Cool-season weeds become most noticeable as they get larger in late January and February, but the seeds begin to germinate this time of year. Look for products that contain dithiopyr, benefin + trifluralin or pendimethalin.
Many lawn preemergence herbicides are available by various companies. They often have names like Crabgrass Preventer, CrabX and others. At this point, the sooner you do this, the better.
I purchased my spring bulbs (daffodils, tulips and hyacinths) Oct. 1, and they have been in the refrigerator since. I planned to plant them all in late November or early December. My question is: Did I make a mistake by chilling the daffodils, and should I plant them now rather than later? Or have I ruined them? — Cindy Morris
You did not ruin the daffodil bulbs by refrigerating them, but it was not necessary. Plant them anytime from now through early December.
The tulips and hyacinths should stay refrigerated until late December or early January and be planted. They should be refrigerated for at least six to eight weeks, but more time will not hurt them.
It is important to wait until the soil has cooled down in late December to plant them. Planting these pre-chilled bulbs into warm soil can cancel the cold treatment and they may not bloom properly.
I see many leaves on my gardenias yellowing and dropping off. I’m afraid that they are dying. What should I do? — Gina Robertson
It is normal for gardenias to shed their oldest leaves in the fall. Up to one-third of the leaves turn bright yellow and drop. The bushes will look somewhat bare until they send out new growth next year, but the newest leaves at the ends of the branches stay green and are retained.
Even though gardenias are evergreen, leaves do eventually grow old and die and are shed from the plant fall/winter/spring. Don’t be surprised to see leaves dropping from a variety of broadleaf evergreens in fall, winter and spring, such as azaleas, hollies and ligustrums.
Narrow-leaved sunflower Helianthus angustifolius
WILDFLOWERS: Be sure to notice the bright gold daisy flowers of the narrow-leaf sunflower (Helianthus angustifolius) blooming so beautifully now along roads and interstate highways. Also in bloom are various white and powder blue asters (Aster), lavender-blue mist flower (Conoclinium coelestinum), goldenrod (Solidago), purple ironweed (Vernonia) and many other fall wildflowers.
PLANT NOW: Vegetables to plant in November include beet, cabbage, carrot, celery, collard, garlic, kale, kohlrabi, leek, lettuce, mustard, onion, peas (green peas, snap peas, snow peas), parsnip, radish, rutabaga, shallot, spinach, Swiss chard and turnip. Purchase and plant transplants of cabbage, celery, collard, kale, kohlrabi, leek, lettuce, mustard, onion, spinach and Swiss chard — or, you can plant seeds of these plants. Root crops, such as beet, carrot, radish, parsnip, rutabaga and turnip, must be grown from seeds sown directly where the plants will grow in the garden.
SWEET IDEA: If you have not dug your sweet potatoes yet, dig them now. Freshly harvested sweet potatoes will not bake properly until they are cured. To cure them, keep them in a warm location with high humidity for a couple of weeks.
TROPICAL TRANSPLANT: Avoid transplanting tropical plants into the ground until next spring. Moving them now will reduce their vigor and lower their chances of surviving the winter. Protect over the winter and plant them next spring.
Dan Gill is a retired consumer horticulture specialist with the LSU AgCenter. He hosts the “Garden Show” on WWL-AM Saturdays at 9 a.m. Email gardening questions to gnogardening@agcenter.lsu.edu.
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