Growing Mountain Laurel
Mountain Laurel is a broadleaf evergreen shrub native to the eastern half of the United States. This shrub has highly ornamental blooms in the late summer and is sometimes trained into a single stem tree. The USDA hardiness for Mountain Laurel ranges from zones 4-9, making it one of the more hardy ornamental evergreens. Mountain Laurel is grown to give four-season interest to a garden while providing habitat for wildlife. Mountain Laurel is known by many different common names, such as Bog Laurel, Swamp Laurel or Sheepkill. Scientifically this shrub is known as Kalmia latifolia and is part of the Ericaceae family, which includes such diverse plants as heather, rhododendron, blueberry, huckleberry and cranberry. Kalmia latifolia grows mainly in part shade to dappled sun, and wooded areas that have rich, humus soil that holds moisture well. A wide variety of cultivars have been developed and range in size from 4 feet to the native size of 15 feet tall. All parts of this plant are poisonous for people and pets.
Planting Mountain Laurel
Mountain Laurel is typically sold growing in a pot, making it quite easy to transplant almost any time of the year. When planting a container grown shrub, the hole should always be as deep as the pot and twice as wide. Gently remove the root ball from the pot and tease loose any roots that look root bound. Place the root ball in the hole at the same depth it was growing in the pot. Back fill the hole with the native soil, without adding any amendments. Adding fertilizers to the planting hole will cause the shrub to keep its roots in just that area instead of spreading out in search of nutrients and forming a supportive network. Water the area around the shrub well and wait a bit for all of the water to be absorbed. Mulching with arborist chips, finely shredded bark or organic compost is beneficial to help protect the roots from cold and heat and also to retain moisture in the soil. Using mulches that decompose will also add nutrients to the soil over time and reduce the amount of supplemental fertilizer needed.
Watering Mountain Laurel
Consistent watering is essential for any newly planted shrub. Establishing good watering habits early will ensure that plants such as Mountain Laurel will thrive with very little supplemental irrigation later at maturity. Watering once or twice a week with around 1 inch of water will keep the soil evenly moist. The best way to do this is with either drip irrigation or soaker hoses. The water gently soaks into the soil directly around the base of the shrub without disturbing the soil or wetting the foliage and wasting water. A long watering once a week will develop deeper, stronger roots than many short watering sessions. Drainage needs to be excellent for Mountain Laurel, especially in the winter when cold soil tends to hold moisture longer. Mulching with organic compost, finely shredded bark or leaves will help to make the soil both lighter and more moisture retentive.
Fertilizing Mountain Laurel
Native trees and shrubs do not typically need supplemental fertilizing when they are provided with their preferred conditions and soil composition. Mountain Laurel prefers an acidic soil that is not heavy or compacted. Acidic soil gives Mountain Laurel access to the nutrients it needs in order to maintain dark green leaves and profuse flowering. If the soil that Mountain Laurel is planted in is not acidic enough, the shrub will start to have leaves that yellow around the veins (leaf chlorosis) and droop. An application of a fertilizer formulated for acid-loving plants will correct these problems. Early in the spring as the new leaves emerge and before the flower buds open, a light application of a slow-release fertilizer will support Mountain Laurel growth for the year.
Pruning Mountain Laurel
The bloom time for Mountain Laurel is early spring to early summer. Pruning after the flowers are finished will encourage bud formation for the following year and help to keep the shrub from dropping large amounts of seed. Mountain Laurel blooms on the previous season's growth. Although any pruning in the late winter will destroy flower buds and reduce flowering for the season, this is also the correct time to prune out any winter damage or to do a hard cutback as an overall growth rejuvenation. Dead, dying, diseased and diagonal branches should all be cut back to a main branch to maintain the naturally open, rounded shape of Mountain Laurel.
Caring For Mountain Laurel in Pots
The smaller and more compact varieties which reach 3 or 4 feet tall can be easily grown in containers year round, to be used on a patio, deck or in the smaller garden. The lovely evergreen leaves and branch structure provide year-round interest. Plant Mountain Laurel in a container with at least a 24 inch diameter. This will give the shrub a solid base that will help to keep the plant from being top heavy as it grows. The soil needs to be a free-draining potting mix that has a slow-release fertilizer formulated for acid-loving plants added. Alternatively, a diluted liquid feed of liquid kelp, seaweed or fish can be applied once a month through the summer. Mulching the top of the pot with organic material such as finely shredded bark or inorganic material like stones, gravel, or glass chips will aid in moisture retention and keep weeds from germinating. Shrubs planted in a pot require diligent watering and should be checked on a daily basis, especially during the hottest parts of summer.
Winter Care of Mountain Laurel
Mountain Laurel is a very hardy and tough shrub that needs very little help to make it through winter. Mulching around the base of the shrub will help to insulate the soil. Make sure to stop fertilizing any pot grown Mountain Laurel by the end of August. This ensures that the roots have time to harden off for winter dormancy. Holding back watering by the end of September also ensures enough time for the shrub to harden off. Evergreens keep their leaves through the winter, but that does not mean they are actively growing. Evergreens slow down dramatically, but do not completely go dormant. Protection from the coldest winds may be necessary and is best done with barriers like burlap wrapped around young plants or other horticultural fabric. Spraying an anti-desiccant on the leaves is not usually necessary and tends to not be long lasting.
Common Care Questions About Mountain Laurel
Why Are Mountain Laurel Leaves Curling?
Curling leaves on a mountain laurel may be the first sign of a serious problem. If circular cankers later appear, your laurel may have a botryosphaeria canker. While there is no cure for this, it can be treated. To treat, prune the branch 6 or 8 inches below where the canker has appeared, and throw the branch away. Be sure to sterilize your pruning tools both before and after the pruning so as not to spread any germs. Laurels are most susceptible to botryosphaeria canker when they are already stressed by heat, drought, or existing damage.
How Do You Save Dying Mountain Laurel?
Doing a fingernail scratch test on the branches and/or the main trunk can help to determine if there's still life in the plant. If there's green under the scratch, there is hope! Laurels are pretty tough and hardy and can be successfully hard-pruned. Cutting damaged, diseased, or sub-par branches (cutting just above a leaf joint) out of the plant will give it a chance to sprout again, and be healthy.
Why Isn't Mountain Laurel Growing?
Mountain laurels prefer and will grow best in acidic soils that are both cool and consistently moist. Application of bark or mulch or wood chips around the shrub can assist in achieving these conditions. They prefer to grow in partially shady areas but will also tolerate full sun conditions. Protection from the wind is also important in allowing them the best conditions in which to thrive, particularly in the most northern of their suitable zones.
What Is The Lifespan Of Mountain Laurel?
The lifespan of well-cared-for laurels can be up to 75 years or even beyond.
Why Is My Mountain Laurel Turning Yellow?
The most common cause of yellowing leaves is a nutritional deficiency of iron. There may be a lack of iron in the soil or the roots may be damaged by over-watering. If the roots have been in soggy, wet soil for too long, they may be damaged and unable to absorb nutrients.
Why Is My Laurel Dying?
There is any number of reasons laurels aren't doing well or are dying, though they are fairly tough and resilient and can often be rejuvenated by a good hard prune. Powdery mildew left spot fungi, and bacterial shothole is amongst the most common causes for laurel decline.
Why Is My Laurel Losing Leaves?
Laurels do not do well in wet, soggy soils, and growing them there can cause oxygen deprivation as well as an inability to absorb nutrients. Oxygen deprivation can cause defoliation.
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Author Robbin Small - Published 6-28-2022