Larches are known for autumnal displays of yellow-gold needles that make them not only particularly attractive but also hardier than other conifers. The tree is bare during the winter and hence the needles cannot get damaged by extreme cold. The needles of larches, which grow in dense clusters, are soft, not sharp or spiny like other conifers. Larches vary in their needles and twig shape and size, and some have a pyramidal shape, while other cultivars have a weeping growth habit. Larches are usually planted as potted nursery plants or bare root specimens in the fall or early spring; these trees transplant well during dormancy. Larches are fairly fast-growing trees that add 12 to 18 inches per year, and they are extremely long-lived in the right conditions. Planting technique is typical for woody plants: Prepare a planting hole that is the same depth as the container or rootball, and twice as wide. Plant the specimen so the top of the root ball is at ground level, then backfill, pack the soil, and water thoroughly. Once established, larch trees are very undemanding, but they will not do well in regions with high air pollution. Depending on the species, the tree might require light annual pruning to control its shape and size.
Light
Most larch species require full sun but some can tolerate partial shade. Refer to the specific cultural needs of the species you are growing.
Soil
Generally speaking, larches prefer a medium-moisture, well-draining soil, but the tamarac (American larch, L. laracina) likes a decidedly soggy environment. In their natural habitat, this species often grows in bogs where the soil contains very little to no oxygen—the soil pores are filled with water instead of air. Any wet, peat-rich soil that mimics that environment is a good location. Larch trees do not grow well in soils with high pH—strive for an acidic to neutral soil (pH 5.0 to 7.4).
Water
Larch trees need ample moisture and won’t tolerate drought. Some types even do well in locations with temporary flooding. Especially during the first two years after planting until the tree is established, make sure that that soil is consistently moist and never dries out.
Temperature and Humidity
Larches are hardy trees that are well adapted to climates with cool summers and cold winters. They don’t tolerate hot climates, especially when paired with high humidity.
Fertilizer
Newly planted larch trees should not be fertilized during their first growing season or two. When a larch is planted in healthy soil rich in organic matter, no fertilizer is ever needed. If a soil test reveals a lack of phosphorus and potassium, apply a complete fertilizer to established trees each spring.
Types of Larch
Popular larch species and varietie grown in North American landscapes includes:
Larix decidua (European larch or common larch) has a mature size of 100 feet in height and 20 to 30 feet in width. There are two popular smaller cultivars: the weeping larch, Larix decidua ‘Pendula’, that only grows 10 to 12 feet tall, and the contorted European larch, Larix decidua ‘Horstmann’s Recurved’ with twisting, curving branches. It is slow-growing to a height of only 4 1/2 to 7 1/2 feet and a width of only 3 to 4 feet at maturity. Larix kaempferi (Japanese larch)has a mature size of 70 to 90 feet in height and 25 to 40 feet in width. Here, too, smaller cultivars are available: the weeping larch, Larix kaempferi ‘Pendula’, the contorted cultivar ‘Diana’, and ‘Blue Dwarf’ with bluish foliage. Larix laricina (Eastern larch, American larch, or Tamarack larch) reaches 40 to 80 feet in height and 30 to 50 feet in width at maturity, The tree is native to most of northern North America. A smaller cultivar is the globe-shaped Larix laricina ‘Blue Sparkler’ that only reaches 12 feet in height and 3 feet in width. It is a less popular landscape tree than the European and Japanese species, due to its insistence on having wet soil.
Other larches that are less commonly planted as landscape trees include:
Larix lyallii (subalpine larch, alpine larch, or Lyall larch) can grow as tall as 80 feet. It is native to northwestern North America and is an important tree for native wildlife. Birds such as the blue grouse, as well as mammals such as mountain goat, feed on its needles.Larix sibirica (Siberian larch or Russian larch) reaches 80 to 200 feet at maturity. It is native to western Russia and Siberia.Laris occidentalis (western larch) can grow up to 150 feet tall. It is native to the northwestern mountains of the United States and has a high wildlife value, as it serves as the host for nest-building animals.Larix gmelinii (Dahurian larch) reaches 40 to 90 feet in height and 15 to 30 feet in width at maturity. It is native to northeastern Siberia, Mongolia, and northeastern China. There are four varieties that originate in different areas and have different needles; one of them is the Japanese variety Larix gmelinii var. japonica.
Pruning
Pruning is not a requirement for larches, but dead or damaged branches should be pruned off as you notice them. If more major pruning is needed to control shape or size, do this during the winter or early spring before new growth starts.
Propagating Larch
Propagating larch trees by vegetative means is not often done outside the nursery trade, since many named cultivars are grafted specimens, in which branches are melded onto species rootstocks. Softwood cuttings are therefore quite difficult to root. More often, larches are propagated through seeds.
How to Grow Larch From Seed
Larch trees are usually propagated from seeds, though this is a time-consuming process that few amateurs want to attempt. Seeds harvested from the ripened cones harvested in fall should first be cold-stratified by storing them in a cool place for a full year, then for an additional three months at 40 degrees Fahrenheit over the second winter. In spring, sow the fully stratified seeds in small pots filled with peat-based potting mix, covered just barely with 1/8 inch or additional potting mix. Place the pots in a cool, dark place, out of direct sunlight, and keep the potting mix moist until the seeds sprout—generally about one month. Move the containers to a brighter location, but without too much direct sunlight, and continue growing them until fall, when they can be planted in the landscape.
Potting and Repotting Larch
Larches are fast-growing trees that are almost never planted in containers, with one exception: when used in bonsai practice. Both European larch (Larix decidua) and Japanese larch (Larix kaempferi) are used by bonsai hobbyists. Larches have short, fine needles that provide excellent texture at an appropriate scale for a bonsai tree. Bonsai larches are grown in shallow pots filled with ordinary potting mix. The plants will need to be lightly watered daily during the growing season, less frequently during the dormant season. Daily pinching is a normal duty for any bonsai practice, and major branch pruning is done in the early spring. These plants are easily trained with wires. Repotting should be every year or two. Larches grown as bonsai need cool, dry air in order for the needles to remain small. These plants are deciduous and are typically grown outdoors or at least moved to a cool location for the winter dormant period when they lose their needles.
Overwintering
Larch trees thrive on cold weather and generally need no protection from the cold. Young trees can be susceptible to wind damage, however, and may benefit from burlap tents or shields for the first year or two. Young seedlings may be susceptible to feeding by deer and rabbits, so protective shields of hardware cloth are sometimes used.
Common Pests and Plant Diseases
The most common disease of larch trees is larch needle cast, which is also called Meria needle cast. It is a fungus that is triggered by wet conditions in the spring. It starts with brown spots on the needles and gradually moves towards their base. The brown needles drop prematurely. The best line of defense is to make sure the tree is from a nursery where the disease is not present. This disease can kill a tree, but it can sometimes be cured with fungicide applications begun just after the buds break in spring. Repeated applications every two or three weeks will be needed until the weather dries out. Chlorothalonil and propiconazole are the recommended fungicides. Larches are also prone to a serious canker disease that is first identified when drops of resin appear on swollen bark lesions. The affected branches should be pruned off and then destroyed or burned. Damage from the larch casebearer, a European moth, starts with tiny caterpillars invading the needles. Later the larvae feed on needles. The needle tips may appear scorched or, if the infestation is heavy, the tree can be completely defoliated. Fortunately, the populations of the larch casebearer are usually kept in check by cold and wet spring weather and late frosts, as well as by naturally occurring predators such as birds and parasitoids wasps that were introduced for biological control of the pest. Chemical treatments include early season application of fungicide, followed by control of the larvae with pesticides.
How to Get Larch to Bloom
The flowers (cones) of larch trees are not particularly showy, and there’s no particular reason to encourage blooms, except for the purposes of harvesting the cones for seeds. In any case, there’s rarely any trouble with cone production, though the tree needs to reach a level of maturity before cone production begins. This can take from eight to 25 years, depending on the species and variety you are growing.
Common Problems With Larch
Tree Is Ugly, Sparse in the Winter
Intrigued by the beautiful yellow needles in the fall, some homeowners who fail to research this tree are surprised when a larch assumes the look of large, barren twig in winter after the needles fall. Remember that larches are deciduous, and will not provide the winter color that other conifers are known for.
Needle Tips Are Burned
Larches are very sensitive to air pollution such as ozone, and high levels of these pollutants may cause the tips of needles to turn reddish-brown. The tree’s growth may also be badly stunted. Larches are best planted in rural areas with good air quality, although the Japanese larch is somewhat better at resisting the effects of urban pollution.
