How tall do hemlock trees grow

Meet the Eastern Hemlock - New England Forestry Foundation

Writing by NEFF Director of Forest Stewardship Chris Pryor

The Eastern Hemlock (Tsuga canadensis) is the tree with the longest lifespan in the eastern forest. It can live to be more than 800 years old, rivaling some of the giant trees of the Pacific Coast—the Coast Redwood, the Sitka Spruce, and the much larger Western Hemlock.

Eastern Hemlock naturally occurs as far north as the southern portions of Canada from Nova Scotia west through Ontario and into the lake states of Wisconsin and Michigan. It extends south through the mid-Atlantic states and continues south along the Appalachian Mountains into Tennessee, North Carolina, and the northern reaches of both Georgia and Alabama.


Eastern Hemlock is an evergreen conifer and so retains its needles year-round. Its short, shiny, dark green needles are flat with two parallel white lines along the underside. The bark on mature hemlocks becomes a reddish-brown with wide, flat ridges. Hemlock bark was the primary source of tannin for the leather industry in colonial America, which led to widespread harvesting of hemlock simply for its bark. Synthetic tanning agents replaced hemlock in the early 20th century.

Age and Size

Eastern Hemlock typically is around 60-70 feet tall with a normal diameter of 1-2 feet, but can be more than 3 feet in diameter and more than 100 feet tall under the right circumstances. Eastern Hemlock is one of the most shade-tolerant trees in New England. This trait allows it to retain its lower branches much longer than other species and survive for many years in the deep shade of the forest canopy. An Eastern Hemlock tree growing in deep shade that is shorter than a person and scarcely thicker than a thumb may be fifty years old, awaiting an opening that will provide it with the light to grow taller.

Wildlife Habitat

Hemlock is an important component of the forest when it comes to wildlife habitat, and numerous mammals both large and small feed on it. Deer and moose will browse the new growth and needles, while squirrels, chipmunks, voles, and other rodents will eat the seeds. Porcupines are known to clip off branch tips while feeding in the canopy. The Black-throated Green Warbler and the Blue-headed Vireo depend on forests that contain hemlock.

Brook Trout

Hemlock stands also provide critical winter habitat for White-tailed Deer; their dense canopies and strong branches will hold snow overhead, allowing the deer to move more easily and to access forage in the shallower snow depths below the canopy. Hemlock also contributes to aquatic habitats as well by providing dense, year-round shade on streams, which keeps water temperatures colder—a critical feature required for native brook trout.

Growing Conditions and Management

Across its range, the Eastern Hemlock can grow on a variety of sites. It is more often associated with moist sites like those along streams, wetlands, and seeps, but can also be found on drier, shallow soils on top of ledges.

Eastern Hemlock is not a particularly valuable species from a timber perspective, so it is not often managed for harvesting, but instead for its ecological value. Hemlock can be managed and regenerated using both even-aged and uneven-aged management techniques, but both require starting regeneration under a partial canopy. Hemlock would be outcompeted by faster growing hardwoods and softwoods under full sunlit conditions. New research at the University of Massachusetts may open up opportunities to use hemlock in cross-laminated timber buildings, which could create new markets for the wood.

Future Challenges

Tsuga canadensis with Woolly Adelgid infestation. US Forest Service / Public domain

An invasive insect called the Hemlock Wooly Adelgid (HWA) poses a major threat to the Eastern Hemlock’s future. It is native to Asia and is thought to have been brought to the United States in the mid-1900s on nursery stock from Japan. HWA is a tiny insect that feeds on the sap of hemlocks by inserting its straw-like mouthpart at the base of the hemlock’s needles, stealing the nutrients needed by the needles and causing them to fall off. Without needles, the tree rapidly dies. The adelgids cover themselves in a white, cottony substance for protection, which makes identification easy.

The insect’s northward spread was thought to be constrained by sustained, cold winter temperatures, but the effects of climate change threaten to remove that barrier and open up more of New England’s forests to the HWA. With no natural predators in New England and little to no natural resistance in Eastern Hemlock, it is difficult to control this insect in a forest setting. Pesticides and horticultural oil can be used on high-value ornamental trees, but they are not viable for widespread use. Biological control using either fungal pathogens or other predatory or parasitic insects show potential but requires more research. The loss of the Eastern Hemlock would be a serious blow to the beauty and biodiversity of New England’s forests, so we can hope these efforts are successful.

Top photo credit: Doug McAbee/Flickr Creative Commons/CC BY-NC 2. 0

Looking for Eastern Hemlock | Extension

The woods are lovely, dark and deep” – Robert Frost, “Stopping by Woods on a Snowy Evening”

The poet could very well have been describing a stand of eastern hemlock when he wrote these famous words.  Eastern hemlock (Tsuga candensis), found from Michigan to the Canadian Maritimes, and from Maine to Georgia, is a common sight in New Hampshire’s forests. It is often found in nearly pure stands, with a closed canopy that casts deep shade. The understory of a mature hemlock stand is often void of understory plants, creating a deep woods, but park-like, feel.

Shade-loving and Long-lived

The shade is an advantage for the hemlock; it is considered to be the most shade tolerant of tree species. Hemlock is so shade tolerant that it can persist in the understory, as a suppressed tree, for up to 400 years! It is not uncommon to see a one-inch diameter hemlock “sapling” that is sixty, eighty, or a hundred years old. This is a prime example of tree diameter not being equal to tree age. A 10 inch diameter hemlock was found to be 359 years old, while other trees of the same age were two to three feet in diameter.

Growing in the shade, hemlocks grow slowly, but can reach large diameters and heights. Hemlocks commonly reach two to four feet in diameter and 100 feet in height. One of the largest hemlocks is eighty-four inches (diameter, not circumference) and the maximum recorded height is 160 feet. These were likely trees growing in the southern part of the range, with longer growing seasons. For a slow-growing tree to reach these sizes, it must be a long-lived species. Eastern hemlocks can take 250 to 300 years to reach maturity, and can live more than 800 years. The oldest eastern hemlock on record is 988 years.

Slow-growing, shade tolerant, long-lived hemlocks have some exacting standards for conditions in which to regenerate.  Though they produce frequent cone crops, with good crops occurring two out of three years, the viability of the seeds is low. Most years the majority of the seeds are empty, or destroyed by insects. In addition, in order for the seeds that are viable to germinate, temperature and moisture conditions have to be just right. Optimally, soil temperatures will be a constant 59 degrees Fahrenheit, though germination is reliable from 44 to 64 degrees. Not only is the narrow temperature range needed, but this range needs to be maintained for 45-60 days for the seeds to reach “peak energy for germination”. Soil moisture is also very important to hemlock seeds, because they are easily dried out, resulting in loss of viability.

Though highly tolerant of shade, once hemlocks are well-established in the understory, they will respond well to release. When overstory trees are removed through cutting or windthrow, suppressed hemlocks will increase in height and diameter growth.

Besides growing in nearly pure stands, hemlock is also found closely associated with white pine, spruce and fir, yellow birch, red oak, and red maple. The species likes moist but well-drained soils, but can also grow on excessively drained sites. It is often associated with lower slopes and along streams and water courses, known as riparian areas.

Used by People

Hemlock was an important species in the early days of the United States. Not for its lumber, but for its bark. High in tannins, hemlock bark was prized for treating animal hides to make leather in a process known as tanning. The role of the tannins is to bind collagen proteins together, so they are less susceptible to being decomposed, thus preserving the leather. Hemlock bark tannins give leather a dark red-brown shade, making it distinct from leather tanned with other species such as oak.

Tanneries were a major industry and employer throughout much of New England during the 1800s. Millions of hemlocks were felled and stripped of their bark. A very small amount of the lumber was used, but most of the downed trees were left to rot. Due to the depletion of the bark source, declining tolerance for the pollution created by tanneries, and economic factors, the leather tanning industry declined significantly by the early 1900s.

Despite the widespread destruction of old growth hemlock stands, hemlock as a species persisted and regenerated, to the point where it now represents 20-25 percent of the softwood timber inventory in the northeast.

Hemlock is now used mainly for lumber and pulpwood. The lumber is strong, holds nails well, and is easily worked when green. It is used for barns, outbuildings, timber frames, and is a popular choice for bridges on logging roads and trails. Demand, however, is limited for structural lumber compared to spruce and fir. Hemlock is difficult to nail when dry, and the green lumber is heavy.

Hemlock lumber yields are low compared to other softwood species because of ring shake, a situation where the wood separates along the growth rings. This renders the lumber worthless. Though the exact cause of ring shake isn’t clear, it is closely associated with tree age, sudden changes in diameter growth through a tree’s life, and bird peck scars.

Due to these factors, hemlock isn’t considered a valuable timber species. Demand is typically steady, but returns to landowners are much lower than white pine, spruce, or fir. A major value of hemlock is for wildlife habitat.

And Wildlife

In areas where spruce and fir are less prevalent, hemlock stands provide important deer wintering habitat. Dense stands reduce snow depths and help to moderate temperatures. These factors are critical in helping deer conserve energy over the winter. As the climate changes, this may become less of a necessity, but in the northern parts of the whitetail deer’s range, it remains an important consideration.

Besides deer, 90 bird species and 50 mammal species use hemlock stands in New England. A number of songbird species focus on using hemlock stands during breeding season, and several species of owl are strongly associated with hemlock stands year-round. Hemlock regeneration supports snowshoe hare, which attract bobcat and fisher. Porcupine feed on hemlock bark and branches. This feeding can help deer in the winter. The branches that the porcupines chew off and fall to the ground provide a source of fresh food for deer. Red squirrels, a favorite food of goshawks, feed on hemlock cones.

Several insects attack hemlock. The most well-known is hemlock woolly adelgid (HWA), a tiny, non-native insect that feeds on hemlock twigs. It is recognized by a white, cotton-like substance that the insect exudes. Feeding by HWA reduces the ability of the tree to produce new twigs. An untreated infestation can kill a tree in 2 to 12 years. The insect is well-established in southern New Hampshire. The good news is that cold winters can keep the spread in check. In 2018, there was 98% mortality due to winter kill. Other insect pests of hemlock include elongate hemlock scale and hemlock borer.

More information can be found at

Eastern hemlock has proven to be a resilient tree, able to persist despite intensive use, large scale land clearing, and insect threats. It is a useful lumber species, important for wildlife habitat, and a common sight in our forests. A changing climate may present the hemlock with additional challenges, but the tree should be a feature of our landscape well into the future.


  • Baumgras, J.E., Sendak, P.E., Sonderman, D.L. (no date.) Ring Shake in Eastern Hemlock: Frequency and Relationship to Tree Attributes. Proceedings: Symposium on Sustainable Management of Hemlock Ecosystems in Eastern North America
  • Canham, H. (2011, May 27). Hemlock and Hide: the Tanbark Industry in Old New York. Northern Retrieved from
  • Ward, J.S., Montgomery, M.E., Cheah, C., Onken, B.P., Cowles, R.S. (2004, May). Eastern Hemlock Forests: Guidelines to Minimize the Impacts of Hemlock Woolly Adelgid. USDA Forest Service. Northeastern Area State and Private Forestry, Morgantown, WV. NA-TP-03-04
  • Yamasaki, M. (2018). Wildlife Habitat Values of Eastern Hemlock Stands in N.H. Timber Crier.

cultivation, medicinal properties and contraindications, photo

Author: Elena N. Category: Garden Plants Retrained: Last amendments:


  • Planting and BOLOGOLOV CARE
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    • How to Seine Seeds
    • The genus is represented by only four species. Most of all in culture, spotted hemlock is known.

      Planting and caring for hemlock

      • Planting: sowing seeds for seedlings - at the end of winter, transplanting seedlings into open ground - in mid-late May.
      • Flowering: in June-July.
      • Lighting: bright sunlight.
      • Soil: fertile, fertilized with humus.
      • Watering: frequent and plentiful.
      • Top dressing: not needed.
      • Reproduction: seed.
      • Diseases: fungal infections.
      • Pests: is not damaged.
      • Properties: is cultivated for medicinal purposes. The plant is very poisonous!

      Read more about the cultivation of hemlock below

      Botanical description

      Spotted hemlock is grown exclusively for medicinal purposes, since the plant does not differ in decorative qualities. What does hemlock look like? Its root is fusiform; a hollow and bare stem, covered on the outside with thin grooves and a bluish bloom, can reach a height of 60 to 180 cm. Reddish-brown spots cover the lower part of the stem, which is why the plant received the specific epithet "spotted". During the first year, the hemlock develops only a bunch of basal leaves, and the stem and the leaves covering it in the next order appear the next year. In the lower part of the stem on the petioles are thrice pinnate leaves resembling parsley in shape. The middle and upper leaves are almost sessile, not as large and less complex in structure than the lower ones.

      In the photo: Hemlock blossoms

      Small white five-dimensional flowers are collected in small umbrellas that form corymbose-paniculate inflorescences with 12-20 rays. Hemlock blooms in July, and fruiting occurs in August-September. The fruits are round or elliptical light brown two-seeded seeds with wavy ribs, which, when ripe, break up into semi-fruits 3-3.5 cm long. A characteristic feature of the hemlock is the mouse smell and the extreme toxicity of all its parts. It is said that Socrates was poisoned with the poison of this plant.

      Growing hemlock in the garden

      How to sow seeds

      The best way to grow a hemlock plant is by seedling: at the end of winter, hemlock seeds are sown in a seedling substrate, shallowly covered, covered with film or glass to create greenhouse conditions and germinated in a warm place. Care for hemlock seedlings should be the same as for flower seedlings. In mid-May or a little later, seedlings are planted in soil well fertilized with humus in a sunny area at a distance of 80-90 cm apart.

      Hemlock care

      As already mentioned, in the first season you should only expect the formation of a rosette of basal leaves. Water the plant as the soil dries out on the site, but it should be said that hemlock is moisture-loving, so watering should be both frequent and plentiful, especially during the dry season. This plant is not afraid of cold, but if the temperature in your area drops below -30 ˚С, you need to cover the hemlock with a layer of spruce branches or straw on the eve of winter, and as soon as the snow falls, throw it over the shelter.

      Pests and diseases

      Pests of hemlock are practically not damaged, but when grown in poorly drained soils, the plant can be affected by fungal diseases that occur due to stagnant moisture in the roots. If symptoms appear, remove diseased specimens, and treat healthy ones with fungicidal preparations.

      Collection and storage of hemlock

      Medicinal raw materials are fruits, leaves, stems and inflorescences of hemlock. Collection of grass - leaves and tops of flowering branches - is carried out at the very beginning of flowering, that is, in June or July, in windy weather.

      Due to the extreme toxicity of the plant, the collection should be carried out with rubber gloves, without allowing children to participate in the process.

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      Plants should be approached from the side where the wind is blowing. Try not to inhale the poisonous fumes emitted by the hemlock, and in no case do not taste the raw materials. To collect grass, you can use a sharp knife, pruner or scissors.

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      After harvesting, thick and coarse stems are removed, and the grass is laid out in a thin layer (no more than 5 cm) on paper or cloth and dried in the shade with good ventilation and a temperature of 20-25 ˚C. In order for the grass to dry evenly, not to cake or rot, it is turned over or ted from time to time. The raw material is ready when the stems of the hemlock break with a dry crack, and the leaves are easily ground into powder.

      Pictured: Growing hemlock in the garden

      The fruits are harvested after they have matured and dried under the same conditions as the grass until the seeds begin to fall freely from the umbrellas.

      Store medicinal raw materials of hemlock in hermetically sealed glass jars, placed in a dry, dark place out of the reach of children.

      Do not store hemlock near other medicinal plants and foodstuffs.

      Shelf life of raw hemlock under proper conditions is 2 years.

      Species and varieties

      In nature, four types of hemlock can be found, but only spotted hemlock is cultivated and used as a medicinal raw material, which we described at the beginning of the article.

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      Properties of hemlock - harm and benefit

      Medicinal properties

      The composition of hemlock includes alkaloids coniine, conicein, conhydrin, pseudoconhydrin and methylconiine, and the fatty oil of the plant contains glycerides of petroselidic and petroselinic acids. The highest concentration of alkaloids is found in unripe hemlock seeds. In addition to the listed components, the flowering grass of the plant contains flavonoids kaempferol and quercetin, as well as other biologically active substances.

      The use of hemlock as a medicinal raw material is advisable for uterine cancer, venereal diseases, induration and tumors of the thyroid, prostate, mammary and lymphatic glands. Treatment of scrofula and diseases of the nervous system with hemlock is justified. Externally, hemlock is used in the form of poultices, baths and compresses for tumors and eye diseases.

      Hemlock medicinal preparations are:

      • herb extract, which is prepared by thickening the plant juice in a water bath;
      • external plaster for tumors, glandular hardenings and calluses;
      • tincture of hemlock leaves and immature seeds in alcohol.

      However, traditional healers believe that hemlock tincture, which is prepared from the flowering tops of the herb, has the strongest healing effect.

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      Since all parts of the hemlock are poisonous, you can use its preparations only according to the doctor's prescription and strictly observing the dosage, but you should know that even therapeutic doses cause an increase in blood pressure and accelerate the rhythm of heart contractions . The action of the coniine contained in the plant resembles the properties of curare and nicotine: in case of an overdose of hemlock preparations, dry mouth, profuse sweating, burning and spasm in the throat, nausea, vomiting, cramps in the stomach and intestines, reddening of the face and the appearance of cyanotic areas are also observed.


      1. Read related topics on Wikipedia
      2. Peculiarities and other plants of the Umbelliferae family
      3. List of all species on The Plant List
      4. More information on World Flora Online

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      Hemlock where it grows and how it looks, uses, useful properties and contraindications + photo

      Hemlock is a very interesting, ubiquitous plant that has a controversial reputation. This herb has long been used for medicinal purposes, widely known for its healing properties. However, it's no secret that hemlock is poisonous and requires precise dosage. Therefore, it must be used very carefully. Let's discuss what hemlock looks like, how it can be treated with it. Separately, we will touch on contraindications for use. The material is provided with photographs of hemlock leaves and fruits, so that even an inexperienced herbalist could not make a mistake.


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      Botanical description of the plant

      wild herbaceous plant with a two-year life cycle. In the first year it does not form reproductive organs and does not form a long stem. The aerial part is represented by a lush rosette of basal leaves. Flowering occurs in the second year, usually in mid-July. Many white thyroid inflorescences are formed. The fruits are tied no earlier than August. The plant belongs to the umbrella family. It reaches a height of more than 1.5 m, under favorable conditions it can grow above human height.

      The leaves of the plant are strongly dissected, openwork, reminiscent of carrots. The lower leaf plates can reach a length of up to 50 cm. The fruits are typical for umbellate, round or ovoid, slightly laterally compressed, brown, about 3 mm long. The stem is smooth, hollow. Spotted or speckled hemlock is ubiquitous. It is called so because the stem has characteristic red-brown spots. Hemlock exudes a peculiar unpleasant smell.

      Hemlock has an unpleasant odor

      The distribution area of ​​this plant is quite wide. It grows along roadsides, in landfills, along river banks, on forest edges, wastelands, vegetable gardens, etc. It occurs naturally throughout almost the entire territory of Europe, in the Asian region with a temperate climate, in China, almost throughout Russia, incl. in the Caucasus and Western Siberia.

      Hemlock is able to grow almost anywhere where winter temperatures do not drop below -30 C° and there is snow cover for the biennial plant to successfully overwinter. In areas rich in nutrients, such as near livestock farms where there is a lot of manure, hemlock grows quite violently. Prefers a moisture-intensive, not waterlogged substrate and well-lit areas.

      Important! Hemlock has a number of popular names, these are: puzzle, poisonous umbrella, stinker, omega, tar, mace, etc.

      Application of hemlock

      Treatment with hemlock has a very ancient history. There is evidence that for the first time small doses of preparations based on this plant were proposed by Hippocrates. Interest in hemlock treatment methods either weakened or increased again. Now, when there is an increase in phytotherapy in our country, this plant is not forgotten either. Patented medicines based on hemlock have appeared, although they are most widely used in homeopathy.

      The most valuable properties of hemlock in the treatment of tumors, including cancer. The strong plant alkaloid kaniin, contained in the organs of the plant, acts as an antigen. It triggers immune responses that, under normal conditions, cannot occur in the human body. In the blood, special antibodies of a protein nature are formed, which, when decomposed, inhibit cancer cells.

      Hemlock is used to treat various diseases

      Several regimens for taking hemlock are popular, among them the methods developed by the following specialists have found the widest use:

      1. Tishchenko V.V. (royal).
      2. Danikov N.I.
      3. Nikoforov Yu.V.

      Therapeutic doses of preparations prepared from hemlock leaves, seeds or stems are used to achieve the following medicinal effects:

      • analgesia;
      • wound healing;
      • improve immunity;
      • fight against tumors of various etiologies;
      • treatment of chronic infectious disorders;
      • soothing;
      • disinfection;
      • improve the functioning of the vascular system;
      • elimination of failures of hematopoietic activity.

      It is recommended to prepare an alcohol tincture, you can use vodka for this purpose. Since the vegetable alkaloids and fatty oils contained in hemlock are better soluble in ethyl alcohol. In addition, the water tincture is stored for only a few days. While an alcohol-based preparation can be stored in the refrigerator for at least 1 year, and often much longer.

      Tip. In the treatment of tumors using hemlock, you can prepare a tincture with good homemade moonshine. Since it is believed that microscopic doses of fusel oils help to get rid of malignant neoplasms.

      Raw hemlock must be collected with care. Since the plant contains a huge amount of essential oils, its inflorescences have a strong smell. When collecting, headaches and ailments may occur. To avoid such troubles, you need to approach the plants from the leeward side.

      Contraindications to the use of hemlock

      Never forget that hemlock is a nerve poison. The strongest alkaloids in the composition of the plant, if the dose is exceeded, can cause poisoning.

      Do not use hemlock in children

      Primary signs of overdose are:

      • irritability;
      • increased blood pressure and heart rate;
      • tremor;
      • nausea;
      • speech disorder;
      • dilated pupils;
      • pale skin.

      In case of poisoning, immediately go to the hospital. Where in the conditions of a hospital the qualified help will be rendered. Otherwise, paralysis, convulsions, respiratory failure, loss of skin sensitivity are possible.

      Important! Even in ancient Greece, hemlock was used as an effective medicine. However, at the same time it was also used as a poison for the execution of dangerous criminals.

      Often people do not believe in the effectiveness of herbal treatment, they treat such drugs as weak. But in the case of hemlock, we must not forget that its chemical composition contains toxic substances. Contraindications for use:

      1. Pregnancy and lactation.
      2. Old age.
      3. Immune system disorders.
      4. General exhaustion.
      5. Postoperative period.
      6. Diseases of the liver.
      Remember that hemlock is poisonous and should only be taken under medical supervision.

      Also, most doctors agree that giving hemlock to children is very dangerous. This is where the “do no harm” statement comes into play. In addition, you need to understand that in the treatment of oncological diseases, it is always necessary to consult a doctor. Since hemlock tincture can cause sometimes unpredictable immune reactions, the specialist should be aware of the use of the remedy. What's more, hemlock can interfere with the effectiveness of chemical or radiation therapy. It is extremely important to consult with your doctor about all the drugs that the patient intends to take.

      Hemlock, like many other poisonous plants, can have a healing effect on the human body. Starting complex processes, accelerating the heart rate, increasing blood pressure, this plant is healing.

      Learn more