Description
Characteristic Features of Hemlock
Hemlock (Tsuga) is a genus of conifers in the pine family Pinaceae found in Asia and North America.
Hemlock is native to Japan. Originally, the Japanese "tsuga" was just a name of the local plant, Abies tsuga; then thanks to the botanist Élie-Abel Carrière, it came to refer to the whole genus.
In the wild, graceful evergreen Hemlock that resembles the fir typically reaches 10-60 metres tall. Lower species (from 50 centimetres to 8 metres tall) are cultivated as ornamental plants.
The root system of Hemlock is widespreading. The slender trunk is covered with grey or brown scale-like bark, often deeply cracked. Thin branches stem horizontally and bend downwards. Flat needles are pointed. The crown is mostly conical or ovoid. The buds are very small. The cones are medium-sized, brown, oblong, and contain small seeds with wings and numerous resinous bubbles.
Hemlock looks good both in single and group plantings. Low-growing varieties are often planted near water (such location provides the plant with necessary amount of moisture) and in rocky gardens. Tall varieties are grown as hedges. In addition, the bark and needles of Hemlock are widely used in medicine, perfumery, and cosmetic industries.
The genus comprises about 10 species. Of them, mainly one species, Eastern Hemlock (Tsuga canadensis), is grown in temperate climates. Although this tree is native to North America, it is now cultivated everywhere. Eastern Hemlock has a cone-shaped crown, drooping branches, fine needles (about 1 centimetre) of green, golden, and other colours, middle-sized brown cones and bark that is red-brown in young trees and grey-brown in mature trees.
Currently, there are about 200 cultivars of Eastern Hemlock with varying needle colours and crown shapes. The most popular are 'Albospicata' (about 3 metres tall, with white yellow shoots); 'Aurea' (about 8 metres tall, with golden shoots); 'Bennett' (with a height of 1.5 metres and a little more in spread, with a fan-shaped crown); 'Conica' (about 3 metres tall, with a conical crown); 'Everitt Golden' (can reach 12 metres tall, has a pyramidal crown and golden needles that get greenish in the winter); 'Gracilis' (a tree growing to about 1.5 metres tall, with deep green needles); 'Gracilis Oldenburg' (a dwarf variety up to 60 centimetres tall with a round crown); 'Jeddeloh' (a small multi-trunk tree with spiral branches and green needles); 'Pendula' (a multi-trunk tree with drooping branches); 'Compacta' (grows up to 3 metres tall and in spread, shrub-shaped, with a conical crown and short dense shoots); and 'Minima' (grows up to 2 metres tall, has a loose rounded crown, short needles, and small branches).
There are less hardy but very ornamental species such as:
Carolina Hemlock (Tsuga caroliniana) occurs mainly in rocky areas. It reaches a height of 10-20 metres and has a topshaped crown, yellow brown stems, and dark green needles. The tip of the needles, in contrast to the above species, is not narrowed.
Northern Japanese Hemlock (Tsuga diversifolia) has slightly pubescent yellow brown shoots and needles of various lengths.
Himalayan Hemlock (Tsuga dumosa) is a tall tree with hanging branches and attractive needles with the white-silvery underside.
Western Hemlock (Tsuga heterophylla) is a fast-growing species that has terracotta bark, a topshaped crown and thin yellow-brown branches.
Mountain Hemlock (Tsuga mertensiana) is a tall tree with a topshaped crown, terracotta branches, bluish-green needles, and large cones.
Southern Japanese Hemlock (Tsuga sieboldii) occurs in the rainforests of Japan and has a topshaped or ovoid crown and linear loose needles.
The Secrets to Successfully Growing Hemlock
In the garden, it is easier to grow Hemlock as well as other conifers from 5- to 7-year-old seedlings. Carefully choose the location because mature Hemlock does not tolerate transplanting. It is best to choose windless areas in partial shade. Although Hemlock grows well in full shade, it will lose its vibrant colouring. Always plant with a ball of soil in moderately moist and fertile soil. Use a mix of humus, leaf mold, and sand at 2: 1: 2. Please note that the soil with high acidity and high lime contents is not suitable for Hemlock. Make sure to provide good drainage with a layer of about 15 centimetres deep, as waterlogging may lead to root rot and death of the plant.
Plant Hemlock in late April to early May or late August to early October 70-75 centimetres deep and keep the root collar at ground level. In group plantings, space the plants 70-140 centimetres apart. If the soil is not fertile enough, add Kemira Universal during planting. During their first two years, feed young trees with phosphate fertilizers for better growth.
Since Hemlock does not tolerate dry air, it is essential to ensure regular watering. Water once a week or more frequently in the summer with a bucket of water per plant. Also, mist with water at least once a month. If the soil is very dense, loosen it slightly no deeper than 10 centimetres. Not all Hemlock species are hardy in moderate climate. Only mature Eastern Hemlock can withstand temperature down to -25 ° C. To avoid freezing of shoots, cover the trees (especially young ones) with spruce branches and mulch with a 5 centimetre layer of peat. Remove the sheltering in April. Hemlock does not need pruning, as it grows very slowly.
Tsuga species are propagated by seed and cuttings. Cultivars are propagated by grafting.
Sow the seeds in March-April in the containers and then transplant the young plants to a greenhouse. Plant out the established trees to a permanent location. Stratify the seeds prior to planting for 4 to 12 months, depending on the species, at 1-5 ° C. However, Hemlock seeds have a long rest period and often germinate only after a year or two.
When you propagate by cuttings, plant the cuttings in the autumn, when the soil temperature is 13-15 ° C.
Potential Problems
In poor conditions, Hemlock can be damaged by hemlock looper moths (larvae of this insect feed on the needles of the tree causing them to turn brown and die off), scale insects (they damage needles of young trees), spider mites (they cause grey-brown spots on the needles), and hemlock rust miteы (they cause yellowing and death of needles). Use specific insecticides to control pests.
Waterlogging often causes fungal diseases, the most common of which is root rot. At the first sign of disease, treat the trees with fungicides, adjust the watering schedule, and ensure good drainage.