Kalmia Latifolia

While there are many plants in North America that have been introduced from other countries or continents, the Kalmia Latifolia, or American Mountain Laurel is a native to North America. The plants are distantly related to Blueberry plants.

pH Requirements

Like blueberries, Mountain Laurels, are acid loving plants. It is important never to plant the shrubs in soil that has recently undergone applications of dolomite lime.

The proper pH for the shrubs is between 5.0 and 5.5. If the plants are not planted in soil that is the proper pH, their leaves may turn yellow from lack of nutrients. If the problem is not corrected, the plants may wither and die.

The plants are hardy from zones 4 through 9. In May, they produce 6 inch wide clusters of buds in hues ranging from white to rose-pink. Each bud in the bud cluster is 1 inch in diameter.

When Kalmia Latifolia grows in the wild, they can reach up to 25 feet in height. In garden settings, the plants may only reach 8 feet tall.

Gardeners may also choose dwarf varieties that are only 3 to 4 feet in height. Some greenhouses have also produced hybrids with more intense flower colors ranging from red to pink.

These plants prefer well drained soil, morning sun and dappled shade in the afternoon. But if they grow in full shade, the plants produce spindly, weak growth.

When grown in full sunlight of 6 hours or more, the shrubs display burned leaves due to drought injury and sunburn.

Planting Kalmia Latifolia

Before planting Kalmia Latifolia in heavy clay soils such as the piedmont soil found through much of the south, gardeners should amend the planting area to improve drainage.

To do this, break up the soil twice as deep as the root ball of the plant and 3 to 4 times as wide with a rototiller or a spade and rake. Then add composted pine bark with the loosened dirt.

The resulting planting bed should be about 20 percent pine bark. This will improve the drainage and add oxygen to the earth to help the plant develop a strong root network.

Once the Mountain Laurel is planted, add a complete organic fertilizer that is formulated for acid loving plants to enhance root growth.

Add the fertilizer to the dirt that you will use to fill in the planting hole at a rate of ½ cup per 3 gallon containerized plant. If the directions on the fertilizer label say otherwise, follow those instructions instead.

To plant the shrub, dig the planting hole twice as wide and the root ball, but slightly shallower. Place the plant into the hole so that the top of the plant root mass is slightly higher than the surrounding soil. This will keep the roots of the plant from becoming waterlogged.

You should mulch around the roots with a 4 inch layer of pine straw, pine bark, or other acidic mulch to help conserve water and keep the roots cool in summer.

Water Kalmia Latifolia immediately after planting. Continue to monitor the plant and water as needed until the roots are established and then whenever drought conditions occur.

Plant Toxicity

Kalmia Latifolia pollen, flowers and leaves are toxic to several species of animals including deer, horses, cattle, sheep and goats.

The plant is not harmful to dogs, cats and other small pets. For this reason, mountain laurel should not be planted on farms or around large domesticated animals.

If you are looking for a plant that grows well in shady, moist areas near azaleas, mountain laurel would make a good addition to your landscape.