Larch (Larix) is a very popular genus in the pine family Pinacea. It contains monoecious coniferous trees that lose their deciduous needles in the autumn.
The origin of the scientific name is unclear. There is a version that this is a Gallic word for resin. Other authors think that the word "larix" derives from the Latin "lardum" (fat). In both cases, the name refers to the resin that the tree is rich in. The Russian name "Listvennitsa" reflects the unique feature of the needles that change colour in the autumn and fall off.
The root system is strong and goes deep down in the soil. The crown is ornamental and can be variously shaped. The wood is very tough and waterproof. The tree has soft flattened green needles that turn golden in the autumn. The ovate cones ripen in the autumn; the seeds are almost triangular and remain viable for about three years. Some wild species can reach 50 metres tall, while ornamental varieties grow just a few metres tall. Larch is highly valued by gardeners not only for its attractive looks but also for high frost resistance (it grows even in the permafrost), hardiness, and rapid growth.
Larch looks good in single plantings and together with the birch, maple, linden, spruce, lilac, cedar, and rhododendron as companion plants. Compact varieties are perfect for rock gardens.
The genus Larch comprises about 20 species native to the Northern Hemisphere. The following species are cultivated as ornamental plants:
European Larch (larix decidua) is the tallest species in the genus with drooping branches. Currently, there are a lot of compact varieties very popular in landscaping. In addition, you can find varieties with cushion ('Corley'), creeping ('Repens'), and twisted ('Cervicornis') shoots.
Siberian Larch (larix sibirica) has large cones (about 5 centimetres) and dark bark. There are a lot of ornamental varieties growing only a few metres tall, for example, compacta (a small tree with a dense crown), decuminata (with a blunted apex), fastigiata (with a pyramidal crown), and pendula (with a drooping crown).
Daurian Larch (larix dahurica) with thick brown or greyish bark, narrow needles that are light green in the spring and yellow-orange in the autumn, and small cones, which may be green or red, depending on the variety.
Larix x czekanowskii is a hybrid of the Siberian Larch and Daurian larch.
Olgan Larch (larix olgensis) is a very ornamental tree that has a dark bark and long, slightly harsh, bluish-green needles but it is rarely used in landscaping yet.
Japanese Larch (larix leptolepis) has a spreading pyramidal crown, reddish bark, and long needles with unique cones. It is frequently grown as a houseplant. Popular varieties are 'Aureovariegata' (needles with yellow spots), 'Blue Rabbit' (a conical crown and bluish needles), 'Vervaes' (drooping branches), 'Diana' (terracotta bark and spiral branches), 'Nana' (a low-growing variety with a conical crown and reddish-blue needles), 'Pendula' (a drooping crown, about 8 metres tall), and 'Wolterdingen' (the height is less than the crown diameter).
Tamarack Larch (larix laricina) has smooth brown or dark grey bark, small cones (about 1 centimetre), and hanging branches. However, it grows slower than the rest of the plants in the genus. The following varieties are popular: 'Aurea' with golden needles and 'Glauca' with silvery-blue needles.
At a young age, all larches tolerate pruning, so you can easily create a desired crown shape and height.
In general, Larches is not fussy and can grow in any location but prefer sunny areas. In the shade, some species cease growing and bearing fruit.
In the garden, the easiest way to grow Larch is to use a healthy four- to six-year old seedling. Plant the seedling in early spring or late autumn about 75 centimetres deep and 2-4 metres apart. Although Larch can grow well in any soil type (worse in sandy soils), it is better to use a mix of leaf soil, peat, and sand at 3: 2: 1. If the soil is heavy, place drainage material on the bottom of the planting hole. Mulch with sawdust or peat.
The care for Larch is quite simple. In early spring, feed with compound fertilizers and water plentifully (about 20 litres per tree) once or twice a week in the dry season. Loosen the soil and remove weeds around young seedlings. Larch is very hardy down to -60 ° C. Young specimen in their first two years needs to be winter covered with paper-based material.
For better growth, Larch requires the symbiosis with mushrooms. At least occasionally, water the tree with washings of freshly harvested wild mushrooms or dig mushrooms with mature spores under the tree.
Propagation by cuttings and grafting is complicated and only performed by specialized nurseries so the gardeners prefer the seed method. To do this, harvest cones in the autumn and take them to a dry place. When the cones unfold, remove the seeds and sow densely before winter or in early spring in the lightweight soil in a sunny location. It should be noted that the seeds germinate poorly, so stratification is recommended. Seedlings need to be regularly watered and weeded. A year or two later, transplant young trees to avoid overcrowding, and when they are 4 or 5 years old, transplant to a permanent location in the autumn or spring.
Larch is sometimes damaged by the needle miners (the needles turn white), scale insects (the needles seem to be covered with white fluff), adelgids (they feeds on the sap, causing the needles turn yellow and get distorted), as well as long-horned beetles, caterpillars of the larch budworm, striped sawflies, caterpillars of larch casebearer, bark beetles, bast beetles etc. If you detect infestation, immediately treat the trees with special insecticides, e.g. Trichlorfon that helps to efficiently manage caterpillars and sawflies. Remove badly damaged shoots.
The roots and trunk may be affected by fungal diseases. At the first sign of rot, treat with copper sulphate. In high humidity, the trees can get fungus schutte causing yellow-brown spots appear on the needles. To prevent progression of the disease, treat with a Bordeaux liquid solution or colloidal sulphur.
Seedlings can sometimes be affected by fusarium. Prior to planting, dip the seeds in a potassium permanganate solution or Fundazole.
The most dangerous disease is larch cancer. Larch cancer causes smooth spots appear on the trunk and branches, then the bark cracks and dies. Since the disease appears only in high humidity, make sure to follow the growing rules and avoid planting Larch in the lowlands and wetlands.