Sand-Myrtle (Kalmia buxifolia) is an evergreen shrub that will grow to 91 cm tall. Glossy, dark green leaves turn to bronze in winter. Blooms clusters of tiny white or pink star-shaped flowers from late spring to early summer. Thrives in full shade or partial shade with moist, well-drained soil. Perfect in gardens or used as a border.
I. Appearance and CharacteristicsÂ
Kalmia buxifolia is a species of flowering plant in the family Ericaceae known by the common name sandmyrtle, or sand-myrtle. It is native to the mid-Atlantic and southeastern United States, where it has a disjunct distribution, occurring in three separate areas. It is known from the Pine Barrens of New Jersey, the Coastal Plain of the Carolinas, and the southeastern Blue Ridge Mountains.
This species is sometimes called Leiophyllum buxifolium, the only member of the monotypic genus Leiophyllum. Genetic analysis supports its inclusion in genus Kalmia.
This species is quite variable in appearance. It is a shrub growing 10 centimeters to one meter in height. The leaves may be alternately or oppositely arranged on the stems. They are oval to lance-shaped and up to 1.4 centimeters long. The inflorescence is a raceme or umbel of up to 18 flowers with white or light pink petals. The fruit is a capsule a few millimeters long.
This species grows in a variety of habitat types in its fragmented range, including sandy plains in the Carolinas and rocky mountain woods.
The Latin specific epithet buxifolia means “box-leaved”, referring to species in the genus Buxus.
The species and the cultivar ‘Maryfield’ have received the Royal Horticultural Society’s Award of Garden Merit.
II. How to Grow and Care
Sunlight
The sand-Myrtle prefers partially shaded conditions due to its origins as a mountain woodland plant. It will grow in both full sun or deep shade; however, deep shade is likely to inhibit flowering. Ideally, your sand-Myrtle should be provided with dappled shade.
Temperature
The sand-Myrtle comprises several different genera of plants, with the most hardy able to tolerate temperatures down to -32 ℃. For the most part, the sand-Myrtle knows how to look after itself and will adapt to local conditions. In severe cold, it may experience damage; measures should be taken to protect the plant from freezing conditions or strong, cold winds. The sand-Myrtle needs more water than most shrubs due to its shallow root system. However, it is important to provide adequate drainage as it can be prone to root rot.
Watering
Thriving in its native habitat’s well-drained soils, sand-Myrtle exhibits a preference for moderate moisture levels. This species is adept at tolerating brief dry spells, positioning it as moderately drought-resistant. Watering should be done once every 2-3 weeks to maintain optimal hydration without over-saturating the soil. Sand-Myrtle typically fares better outdoors where it can benefit from natural rainfall patterns, especially considering that as an evergreen plant, consistent moisture contributes to its year-round foliage retention.
Soil
The sand-Myrtle prefers moist acid or sterile soils with good drainage. Some varieties, such as Mountain sand-Myrtle, are sensitive to heavy clays, although Bog sand-Myrtle will only grow in wet or poorly-drained sites. Mountain sand-Myrtle will often do better in a raised bed that allows for extra soil to provide better drainage. Most varieites do best in soils rich in nutrients and organic matter.
Soil acidity is very important to the sand-Myrtle, particularly when the plant is young, with an ideal soil pH of between 4.5 and 7.5. pH testing will show soil acidity; these can either be bought from home stores, or a home-made kit can be made using red cabbage. If the soil shows insufficient acidity, a layer of wood chips or evergreen bark mulch should be added. In the spring, plant food formulated for acid-loving shrubs, such as rhododendron food, should be used. However, care should be taken using plant food when the plants are young, to prevent burning the plant’s roots.
Fertilizing
Fertilize sand-Myrtle sparingly with balanced, slow-release fertilizers in spring to bolster growth and flower production. Roots are sensitive, so apply per manufacturer’s guidelines—typically a light scattering around the plant’s base, avoiding direct contact. Adjust feeding with seasonal growth; less in fall to prepare sand-Myrtle for dormancy. Over-fertilization risks harm; less is often more. Water deeply post-application to aid nutrient absorption.
Planting Instructions
The sand-Myrtle can be planted from early spring once the danger of late frost has passed, and also during the summer. The soil should be cool when the sand-Myrtle is planted, with shrubs spaced 1.5 to 2 m apart. The sand-Myrtle should be situated away from direct strong winds, particularly in colder climates. The shrub’s crown (where the trunk meets the roots) should be at or slightly above ground level to avoid rot.
Pruning
Leggy plants can be avoided by pruning heavy branches to between 30 cm and 1 m in length. They can be pruned all the way back to 30 cm off the ground if needed, which will result in a bushier plant within a few years. The removal of fruit capsules as they develop during flowering will also encourage vigorous plant growth and blooming. If the aesthetic of flower clusters or the appearance of berries is undesirable, flower clusters can be carefully removed.
Because the plant’s buds set in the spring and early summer, pruning of the sand-Myrtle should be done straight after flowering in the spring/summer. Deadheading expired flower blooms throughout the season will help flower production the following year.
Propagation
Sand-Myrtle, a member of the Heath family, thrives in well-draining, acidic soil similar to that of its relatives. For effective propagation, it’s essential to take semi-hardwood cuttings during the plant’s active growth phase. To promote root formation, treat the cuttings with a rooting hormone and provide a humid environment. Starting sand-Myrtle from seeds can be more challenging, as this method requires stringent conditions for germination. Cuttings tend to be the favored approach, as they ensure genetic consistency and typically yield more reliable results.
Transplanting
Transplant sand-Myrtle as the days grow warm, but before summer heat peaks, ensuring it thrives in well-drained, acidic soil. Choose a partly shaded spot and gently introduce it to its new home for best results.
III. Uses and BenefitsÂ
It is perfect for beds and borders, underplanting shrubs and roses, city gardens, cottage gardens, rock gardens, woodland gardens, or native plants gardens.
IV. Harvesting and Storage
Seeds are easy to collect and can be stored for many years before planting. Seed capsules can be harvested as soon as they have turned brown and dry, to be put in a paper bag for several weeks whilst they dry further. The fully dried capsules will open, allowing the seeds to be shaken loose. Stored at room temperature and out of light, seeds will remain viable for several years. Before planting, seeds can be pre-treated with gibberellic acid to aid in germination.
