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Landscaping

Mountain Laurel is a broad-leaved evergreen that looks good all year and has exquisite blossoms from late spring until early summer. The growing conditions that Kalmia prefer are quite similar to rhododendron and in addition Kalmia flower clearly later. Therefore they are ideal partners for rhododendron and other Ericaceae.

Kalmia can and do fit in many garden styles, including formal, rock and Japanese. They are particularly suited to translate natural landscapes into condensed forms around gardens and parks.

Kalmia in the Background

The large native plants or the cultivars can be grouped together for screening, to soften buildings and to dress off the edge of wooden areas.

Hedges

With Kalmia one can plant natural growing borders. When there is not enough space, they can be easily shaped.

Individual Placement

When you use Kalmia only for screening, you will never realize the unique shape of the bud an open flower. In each garden with Mountain Laurel there should be a special place, where the visitors have a direct view on these details. That can be near a place with seats or close to a path or a gate. When a nice flowering Kalmia is situated in an area, that you pass every day, you can watch the amazing change that is happening while the buds open to flowers. Most of the Kalmia cultivars have got a compact habit but do not look ungainly when they are situated on a separate place.

Companion plants

The list of possible companion plants seems endless. Important are the periods of bloom, fall colour, mixes of deciduous and evergreen (needled and broad-leaved) plants, annuals and perennials. Laurels are low-maintenance plants and can be an attractive major component in many gardens.

Grow Kalmia

The following information is given for Mountain Laurel (Kalmia latifolia) and its cultivars.

Site Selection

In places, where Rhododendron and other ericaceous plants are growing successful, Kalmia can be grown easily. They sustain more sunlight and can stand with less moisture. Hardiness is remarkable.
Kalmia latifolia and its cultivars are suitable as companion plants. They can be arranged in groups but are also fine solitaires. Because of their smaller foliage they make better hedges than most of other evergreen shrubs.

Soil

Kalmia prefer well-drained, acid and not so heavy soils. Established plants are tolerant of drought conditions but do best when soils are kept moist but not wet.

Fertilizing

Mountain Laurel and most of its cultivars can survive in very infertile soils but will thrive with moderate fertilization. Applications should never exceed the amounts recommended for Rhododendron.

Watering

It is only necessary, when plants are young or during a long drought. A good soaking every one or two weeks during dry periods is preferred to daily watering or sprinkling. Wetness has to be avoided.

Pruning

Kalmia can easily be pruned. Best time is early spring, before growth starts. A well pruned plant will get a denser and compacter habit.

Transplanting

Planting is quite easy when the soil is well-drained and acid. If the soil is too poor, humus can be added. The texture of the soil can be improved by adding pine bark, leaf mould or wood chips.
Roots do not like stagnating water. A good drainage should be made before planting. If that is too difficult, the whole site can be covered with a mix of mulching material. Break up the soil to get a good connection to the covering material.
Roots should not be dry before planting and when the Kalmia is well situated at the new place, it should be well watered.
When you are planting or transplanting Kalmias never hold the plant above the rootstock. This could cause damages at the root crown. It is better to handle the plant directly at the root ball or to operate it with the spade under the root ball.
Within five years it is quite necessary to watch the roots if they are too dry or too wet.
Fertilizing is not yet needed.
The best time for transplanting laurel is from September until Mai. Weather should not be too warm and dry. On the other hand it should not freeze. Temperatures above 40°F (4,5°C) are best.
It helps a lot, when the plants were covered with leaf mulch after transplanting.

Propagation

The following information is given for Mountain Laurel (Kalmia latifolia) and its cultivars.

Raising laurels from seeds is possible when you want to propagate species. For crossing new sorts it is essential. Hybrids can only be multiplied asexually. Usually this is done by cuttings or grafting. But it is difficulty to propagate Kalmia cultivars this way. Tissue culture, also called micro propagation made it possible to produce Kalmia hybrids in a rate that is adequate for commercial purpose. If you only need small quantities you can try to propagate them by layers.

Seeds

Only ripe seed is capable to germinate well. Indoors you can sow by the beginning of December under additional lights. The medium used for germination can be similar to media recommended for Rhododendron. A mixture of sand and peat covered with sphagnum that is cut into short pieces. The seeds should be sown on the surface of the mix and not covered. They need light and will not germinate in the dark. A moist medium and high humidity are necessary for germination. The best temperature for germination and initial growth is between 70 and 75 °F (21 and 24 °C). Most seeds will germinate in 10 to 20 days.

Cuttings

It is difficult to propagate Kalmia by rooting stem cuttings. The use of auxins, fog and special rooting media can help but these techniques are not always helpful for commercial success. Hybrids that can be easier propagated by cuttings have got a notice in the Register of KalmiaRegister of Kalmia. Cuttings from young plants generally root more readily than those from older plants. According to the regional climate different times are the best to take cuttings. January, March, June, July and August-to-December each has been reported as the best time. The medium should be kept moist. It can be a mix of sand and peat. Best temperature is between 70 and 80 °F. Additional light for at least 16 hours can be helpful.

Grafting

Kalmia latifolia can be grafted with little difficulty. On the whole this method is not yet normal in nurseries. You can safe a precious and week plant for example, by grafting scions on another grown up plant.

Layers

Layering is a slow and laborious method. To propagate just a few plants, the technique is as practical as any; however it has little or no appeal at the nursery where more efficient methods are needed. To layer a selection, remove about 1 inch of soil beneath a low-lying stem. Make several shallow, encircling knife cuts in the underside of the stem. Bend it to the ground and peg the stem down. Cover it with leaf mould or peat moss and soil. After two growing seasons the new plant can be removed.

Micropropagation

Tissue culture has made the large-scale propagation of Kalmia hybrids highly successful. There are biological laboratoriesbiological laboratories that produce great quantities of plants every year by this method.

Pests & Diseases

The following information is given for Mountain Laurel (Kalmia latifolia) and its cultivars.
Mountain laurels are remarkably free of trouble caused by pests and diseases compared with most other cultivated plants. In addition they are perfectly hardy.

Pests

In cultivation one cannot avoid that insects, mites and so on are coming from accompanying plants. Especially those that prefer Rhododendron and other Ericaceae should be mentioned.
You might find damages on Kalmia by Vine Weevil, Lacebug and Whitefly. Parts of the young shoots might be sometimes eaten away by caterpillars.
Normally deer avoid the poison foliage. Slugs keep away from the leathery leaves.

Diseases

Phytophthora root rot or wilt is a serious fungal disease. It is worst at high temperatures and in moist situations, especially if the drainage is poor.
Leafspot and leafblight are one of the most common diseases on Kalmia. They can be found particularly on plants that are crowded or shaded. Because under this conditions humidity is high and moisture is retained on the foliage for long periods. Symptoms generally appear as yellow, brown or reddish spots. Normally plants would not die but look very unattractive. Best thing to avoid leafspot is to hybridize resistant cultivars.

Miscellaneous Afflictions

Salt damage occurs on plants that are over fertilized. Leaf tips and edges turn brown. Leaching with water may be worthwhile.
Chlorotic symptoms can result from soil with a high pH rate or from a wrong type of fertilizer. When plants are growing in sunlight the colour of the foliage normally looks lighter green than grown in the shade.
Frost damages especially on young shoots can only occur under bad conditions.

Links

Publications Concerning Kalmias