Oxalis is a landscape scourge, and getting rid of it will take time and effort: Dan Gill explains how - NOLA.com

Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu. 

We are having a terrible time with oxalis in our landscape. It is in some of our flowerbeds and even in the lawn. We've tried to control it in the past, but we don't seem to be making much headway. How do you recommend controlling this weed? — Andy

Oxalis, also called woodsorrel, is a cool-season perennial weed that is very difficult to control. The most active growing season is October to May. With its three-part leaves, oxalis resembles and is sometimes called clover. But it is not related and is far more common than clover in flowerbeds.

There are several species of oxalis with different leaf shapes growing in our area, but they all have the three-part, clover-like leaves. Control requires persistent effort over time. It takes repeated herbicide applications to eradicate this weed.

Oxalis has tubers and spreading roots that must be dug out with a trowel when hand-weeding; otherwise the weed returns with a vengeance.

PROVIDED PHOTO

PHYSICAL CONTROL IN BEDS: When oxalis is growing in beds, hand weeding can be done. However, this plant produces tubers, roots or bulbs that break off and stay in the ground during hand pulling, and the leaves will soon grow back. When hand weeding, you must dig up and remove the roots and bulbs attached to the leaves using a trowel or weeding tool.

This should be done frequently and repeatedly through the cool season when oxalis is in active growth.

HERBICIDE CONTROL IN LAWNS: The best lawn herbicide to use to control oxalis in St. Augustine and centipede lawns is Atrazine. Make two applications following label directions during mild weather (temperatures in the high 60s or above) anytime during the winter or spring.

Any spots or small patches of oxalis that are noticed after that should be spot treated by just spaying the spot of oxalis.

HERBICIDE CONTROL IN BEDS: There are no selective herbicides that will only kill the oxalis and not damage ornamentals if it gets on them.

The nonselective systemic herbicide glyphosate — KillzAll, Eraser Grass and Weed Killer, Roundup, and other brands — is the most effective. But you must be persistent and make several applications as the oxalis reappears; generally, three to five treatments are required. Use glyphosate carefully as it will damage or kill any plants if it gets on their foliage.

Shield the foliage of desirable plants with a piece of cardboard during spraying or cover those plants with plastic bags. Or put a funnel-like device on the end of your sprayer to focus the spray only where you direct it. Do not spray on windy days.

Although we can use glyphosate close to desirable plants, it is critical not get glyphosate on their foliage. Spray just enough to thoroughly wet the foliage of the oxalis.

Oxalis often grows mixed in among the foliage of low-growing ornamental plants and ground covers. In this situation, use a wick applicator to carefully smear the herbicide just on the foliage of the oxalis. You will need to make several applications for it to be effective.

When planting amaryllis bulbs, do my pots need to have a drainage hole? — Asa

Now is a great time to plant amaryllises for blooming over the holidays. Yes, whenever we grow plants in containers, it is highly recommended to use pots with drainage holes. Otherwise, it's too easy for the soil to stay too wet, which would be unhealthy for the roots.

As the flower stalk grows tall the plants can become top heavy, so I generally use clay pots to grow amaryllis plants indoors. The weight of the clay pot provides more stability.

Now is the time to plant cabbage.

STAFF PHOTO BY BRETT DUKE

Garden tips

PLANT NOW: Vegetables to plant in December include beets, cabbage, carrots, celery (transplants), Chinese cabbage, collards, garlic (toes), kale, kohlrabi, leeks (transplants), lettuce, mustard, onions (transplants or sets), radish, rutabaga, shallots (sets), spinach, Swiss chard, turnips and Brussels sprouts (transplants).

WINTER TINTS: Varieties of certain shrubs, such as azaleas, nandinas and junipers, will develop a purplish or burgundy tint to their foliage during cold weather. This is natural and no cause for worry. They will turn green again in the spring.

RAKE IT OFF: Do not allow a layer of fallen leaves to accumulate over the lawn for more than a few days or a week. The leaves block light from reaching the grass and can weaken it. Rake or otherwise remove the leaves weekly. Use the leaves for mulch or put them in your compost pile.

TAKE THE WINTER OFF: If you don't garden as much in the winter and won't be using tools until spring, it's important to store them properly. Clean tools thoroughly and coat the metal with a light film of oil to prevent rust. Drain the lawnmower gas tank and clean it.

FLOWERS FROM SEED: Cool-season flower seeds that may be sown now include alyssum, candytuft, forget-me-not, poppies, ornamental cabbage and kale, lobelia, dianthus, calendula, sweet pea, larkspur, cornflower and annual phlox. Transplants of these and other types of cool-season bedding plants can also be purchased from area nurseries and planted now.

The colors and fragrances of flowers are the delight of gardeners. There is more to flowers, however, than meets the eye or the nose. Your tas…

Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu.

Home vegetable gardeners put a lot of effort into producing the crops they put on the table. When you consider the work that goes into produci…

Adblock test (Why?)