By: Tonya Barnett, (Author of FRESHCUTKY)
Mountain laurel (Kalmia latifolia) is a showy ornamental shrub that is hardy to USDA zones 5 through 9. In the spring and early summer, mature plants put on a dazzling display of small clustered flowers. While their beautiful blooms and evergreen foliage attract the attention of many landscapers, they are also prized for their wide adaptability, growing well in both shade and in sun.
Though these plants are generally trouble-free, there are some issues which may cause plant vigor to suffer when growing mountain laurel. What’s wrong with my mountain laurel, you ask? Find out about common problems with mountain laurels here and how to fix them.
Issues with mountain laurel plants may occur for a wide variety of reasons. Whether injury has been caused due to weather, fungal infections, or bacterial issues, it is important to be able to quickly identify the problem and determine the best course of treatment for plants. While some causes of mountain laurel problems may be incidental, others may progress and spread to other laurels within the garden without intervention from the gardener.
Below are some of the more common mountain laurel issues you might come across when growing these shrubs in the landscape.
Among one of the most common problems with mountain laurel results from damage done during inclement weather. Since this shrub is an evergreen and maintains foliage throughout the winter, it is susceptible to damage done by cold temperatures. This most often occurs in gardens located in the coldest region of its hardiness zone.
Gardeners living in areas which experience heavy snow and windy winter conditions may also notice broken branches and evidence of browning leaves. To maintain these plants, be sure to remove any dead limbs and dispose of them. Removal of plant materials from the garden is an important step in preventing disease, as many organisms may live and overwinter on dead wood. Plants should recover in the spring as new growth resumes.
Mountain laurel bushes are also sensitive drought. Signs of damage incurred by dry conditions include drooping leaves, browning of the leaves, and sometimes cracked stems. Drought-stressed plants are often more susceptible to other pathogens as well. Be sure to water mountain laurels deeply, at least once a week, throughout the active growing season.
One of the first signs gardeners may notice about unhealthy mountain laurel plants is the change in appearance of the leaves. These shrubs can be affected by numerous forms of fungal infections as well as blight.
As the name implies, leaf spot is recognizable by the presence of dark “spots” on the leaves. Infected leaves most often fall from the plant. These should be removed from the garden, as this waste can promote further spread of the issue.
With proper garden maintenance and clean-up, it is rare that issues with leaf spot become a serious problem.
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The cold decimated many annuals, but not all, according to Webster. Some, such as petunias and begonias, were left limp and flattened in the dirt. These should be pulled.
Others, like hardy pansies, should survive and come back strong, at least until the hot weather arrives in May or June. Still others, including snapdragons and dianthus, may recover, although they probably suffered bloom damage and will need to be deadheaded.
“Except for the plants that are obviously dead, give the rest a few weeks to see if they’ll survive,” Webster said.
None of this counts, he added, for plants that were in outdoor pots, which froze through. “Anything in pots is not salvageable and will have to be replaced,” Webster said.
While popular perennials, such as lantana, salvia, plumbago and shrimp plants, have all died back to the ground, the roots may still be alive. So once warm weather returns, fingers crossed, they’ll grow back.
Even during normal winters, tropical plants like bougainvillea and hibiscus tend to die back to the ground before regrowing from the roots. This year they’re either completely dead or, if they do come back, the regrowth won’t be as strong because the ground got colder, and the cold went deeper, for a longer period of time, according to Labay.
Pride of Barbados, on the other hand, froze back to ground level but will likely return come warm weather. “I’m not anticipating any problems with pride of Barbados,” Webster said.
The good news with many mature plants like philodendrons is that they have an extensive root system. So although the tops may be frozen, they’ll bounce back faster than when they were new.
The bottom line is, you should wait several weeks before cutting anything back. Not only will plants that look dead still be alive, but South Texas has had freezes as late as the end of March. Leaving the branches in place will help insulate the rest of the plant, according to Labay.
Once the threat of a freeze has passed, check the branches to see if they’re truly dead. If they’re still limber and green inside, leave them be. If not, cut them back to about 2 inches above ground level or to the height of the bedding mulch. They should start sending out new shoots soon.
Pick out the mountain laurel that you want to transplant. Whether you are digging up an existing mountain laurel to replant in a different space or buying one from a nursery, make sure it is less than 2-1/2 feet in height. Mature mountain laurels do not transplant well.
Decide on where to plant your mountain laurel. It should be an area that receives full sun if you want it to bloom. While mountain laurels will still grow in shaded areas, they will more than likely not bloom. The soil should be well drained.
Use a shovel to dig a hole in which to place your mountain laurel. The hole should be at least twice as large as the root base.
Place the potting soil in the bottom of the hole. There should be enough potting soil so that when the plant is sitting in the soil, the roots are sitting just beneath the surface edge of the hole.
Dig up your mountain laurel for transplanting. If you are taking the plant out of a pot, press the sides of the pot to loosen the soil and roots. Gently pry the plant from the pot, taking care not to damage the roots. If you are digging the plant out of the ground, use a shovel to dig. Start digging far enough out from the base of the plant to ensure minimal damage to the roots. Gently dig underneath the plant and lift it out of the ground.
Loosen the roots of the mountain laurel slightly, taking care not to damage the roots.
Place the mountain laurel in the hole on top of the potting soil. Gently fill in potting soil to completely surround the plant. Pat the soil down so the plant is securely in the ground and does not move.
Water the plant well. When you first transplant a mountain laurel, you will need to keep it well watered at first. After it is established, however, it does not need supplemental watering except during periods of extreme drought and just before the ground freezes in winter.
Fertilize your mountain laurel twice a year with a small amount of fertilizer for acid-loving shrubs in early spring and late fall. Throughout the year, you can place a 2- to 3-inch layer of organic material or mulch around the plant to help protects its roots and to retain soil moisture during periods of heat or dryness.
While fertilizing a mountain laurel will make this slow-growing shrub shoot up faster, it will also inhibit blooming. To ensure a nice annual show of flowers, fertilize only once or twice a year.
The mountain laurel is an evergreen but is susceptible to winter burn. If your mountain laurel is not protected from wind by a natural shelter, create a protective screen out of burlap to protect it. Take care when wrapping it to ensure air circulation is not blocked.
Overwatering can kill mountain laurels. Water generously when the mountain laurel is first transplanted, but avoid overwatering established plants.