hemlock foliage and cones

Hemlock Species Guide

What Is Hemlock?

Hemlock is a type of tree that grows in many parts of the world. It has long needles that are dark green in colour and small cones. Hemlock trees can grow quite tall, up to 100 feet in some cases, and they are often found in forests or other natural areas. Hemlock trees are also known for their distinctive smell, which is sometimes described as a mix of pine and citrus. In addition to its natural beauty, hemlock has a fascinating history, having been used for everything from traditional medicine to poison. It is also sometimes grown as a bonsai tree, which requires careful attention and a lot of patience. Continue to read to expand on each of these points.

Historical significance of hemlock

Hemlock has a long and fascinating history, with many significant events and cultural references tied to the plant. Here are some key points:
  • Hemlock was used in ancient Greece as a method of execution. The philosopher Socrates famously drank hemlock poison as a form of punishment for his philosophical beliefs.
  • In traditional medicine, hemlock was used for a variety of ailments, including coughs, colds, and digestive problems. It was also used topically for skin conditions.
  • In North America, hemlock was used by Native American tribes for medicinal purposes, as well as for making tools, baskets, and other useful objects.
  • Hemlock bark was used by early European settlers in North America to tan leather, due to its high tannin content.

Physical characteristics

Here are some key physical characteristics of hemlock:
  • Needles: Hemlock needles are typically around 0.4-0.8 inches (1-2 cm) long and dark green in colour. They grow in pairs along the stem and have a slightly flattened shape.
  • Cones: Hemlock cones are small and egg-shaped, typically around 0.5-1 inch (1.2-2.5 cm) long. They have thin, woody scales and are often found hanging downwards from the branches.
  • Bark: Hemlock bark is gray-brown in colour and has a distinctive scaly texture. As the tree ages, the bark becomes more deeply furrowed.
  • Size: Hemlock trees can grow quite large in the wild, with a typical mature height of 40-70 feet (12-21 meters). However, when grown as a bonsai, they can be as small as a few inches tall.
  • Smell: Hemlock has a distinctive scent that is often described as a mix of pine and citrus.

Geographical distribution

Hemlock is found in various parts of the world, although it is most commonly found in temperate regions of the Northern Hemisphere. Here are some key points on the geographical distribution of hemlock:
  • North America: In North America, hemlock is found primarily in the eastern and western regions of the continent. Eastern hemlock (Tsuga canadensis) is found from the Maritimes to northern Georgia, and west to Minnesota and Manitoba. Western hemlock (Tsuga heterophylla) is found along the western coast from Alaska to northern California.
  • Asia: Hemlock is also found in various parts of Asia, including Japan, China, and Korea. In Japan, the Japanese hemlock (Tsuga diversifolia) is an important tree in forests and also cultivated as a bonsai.
  • Europe: Hemlock is found in various parts of Europe, including the United Kingdom, where the common hemlock (Conium maculatum) is a common plant that is sometimes used for medicinal purposes.
  • Other regions: Hemlock is also found in other parts of the world, including the Caucasus Mountains and the Himalayas.

Growth requirements

Hemlock has specific growth requirements to thrive, including soil type, water, light, and temperature. Here are some key points on the growth requirements of hemlock:
  • Soil: Hemlock prefers well-drained soil that is slightly acidic, with a pH range of 5.0 to 6.5. It can tolerate a wide range of soil textures, but prefers loamy or sandy soils when planted in the landscape, if planting for bonsai you will need to use a more open mix using Akadama, Pumice and Lava Rock.
  • Water: Hemlock requires regular watering, especially during dry periods, to maintain adequate moisture levels in the soil. However, it is sensitive to waterlogged conditions and can be damaged by flooding or poor drainage. Using a good free draining soil can help prevent water logging.
  • Light: Hemlock grows best in partial shade to full shade conditions, although it can tolerate some sun exposure. In general, younger trees require more light than older trees to grow and develop properly.
  • Temperature: Hemlock grows best in cool and moist climates, with temperatures ranging from 7-21°C (45-70°F) during the growing season. It can tolerate some frost and cold temperatures, but is sensitive to extreme heat and drought conditions.
In addition to these requirements, hemlock is also susceptible to certain pests and diseases, including hemlock woolly adelgid and hemlock sawfly. Proper care and maintenance, including regular monitoring and treatment, can help keep hemlock healthy and thriving. When grown as a bonsai, hemlock requires careful attention to soil moisture, pruning, and fertilization to ensure healthy growth and development, but we will talk about bonsai specific care later in this article.

Hemlock in Medicine

Hemlock has a long history of traditional medicinal uses, although it is important to note that it can be toxic in large doses and should only be used under the guidance of a qualified healthcare practitioner. Here are some traditional medicinal uses of hemlock:
  • Pain relief: Hemlock was traditionally used as a pain reliever for a variety of conditions, including headaches, menstrual cramps, and toothaches. The plant contains compounds called alkaloids, which have pain-relieving properties.
  • Respiratory conditions: Hemlock was also used to treat respiratory conditions such as coughs, bronchitis, and asthma. The plant contains essential oils that can help relieve congestion and inflammation in the respiratory system.
  • Sedative: Hemlock was used as a sedative for anxiety, nervousness, and insomnia. The plant contains compounds that can help promote relaxation and calmness.
  • Topical use: Hemlock was also used topically as a poultice for wounds, burns, and skin irritations. The plant contains compounds that can help reduce inflammation and promote healing.

Hemlock as a Poison

Hemlock is a highly toxic plant that contains several potent toxins, including coniine and γ-coniceine. These compounds are found in high concentrations in the seeds, flowers, and leaves of the plant and can cause a range of symptoms when ingested.
When consumed, the toxins in hemlock interfere with the normal functioning of the nervous system, leading to paralysis and respiratory failure. Specifically, the compounds in hemlock bind to and block nicotinic acetylcholine receptors, which are responsible for transmitting signals between nerve cells and muscle cells. This results in muscle weakness, paralysis, and ultimately, respiratory failure.
The symptoms of hemlock poisoning can appear rapidly and include nausea, vomiting, dizziness, tremors, muscle weakness, seizures, and respiratory failure. The severity of symptoms depends on the amount of hemlock consumed and the individual's sensitivity to the toxins.
It is important to note that hemlock is a highly toxic plant and can be fatal if ingested. As such, it should never be consumed or used as a home remedy or self-treatment. If you suspect that you or someone else has ingested hemlock, seek emergency medical attention immediately.

Hemlock as Bonsai

Hemlock is a popular choice for bonsai enthusiasts for several reasons. Here are some reasons why hemlock is used as a bonsai:
  • Attractive foliage: Hemlock has small, needle-like leaves that are attractive and add to the overall aesthetic appeal of the bonsai. The needles are typically dark green in colour and have a glossy appearance. The compact nature of the needles makes it easier to create a padded look for you bonsai.
  • Interesting trunk and bark: Hemlock has an interesting and unique trunk structure, with a distinctive fluted appearance. The bark is also attractive, with a gray-brown colour and a rough texture that adds to the bonsai's overall visual appeal. Trees with rough bark tend to give an aesthetic appearance of age.
  • Tolerant of shade: Hemlock is a shade-tolerant tree, which makes it a good choice for low-light bonsai environments like those with balconies that only receive a short amount of sunlight each day.
  • Long lifespan: Hemlock bonsai trees have a long lifespan and can live for several decades or even centuries with proper care and maintenance.
  • Cold hardiness: Hemlock is a cold-hardy tree that can withstand freezing temperatures, making it a good choice for bonsai enthusiasts in colder climates.

Here are some tips for growing a hemlock bonsai:

  1. Location: Hemlock bonsai trees prefer a cool, Partly shaded location If they are in a full sun environment then the watering schedule will need to be maintained.
  2. Watering: Hemlock bonsai trees prefer moist soil, so it is important to keep the soil evenly moist but not waterlogged. Water the tree when the soil begins to feel dry to the touch.
  3. Soil: Hemlock bonsai trees prefer well-draining soil that is slightly acidic. A good soil mix for hemlock bonsai trees is Akadama, Pumice and Lava Rock in a 1:1:1 Ratio.
  4. Fertilizer: Hemlock bonsai trees should be fertilized with a balanced, slow-release fertilizer during the growing season. Avoid over-fertilizing, as this can lead to excessive growth.
  5. Pruning: Hemlock bonsai trees should be pruned regularly to maintain their shape and size. Pruning should be done in the spring after the first flush hardens or in the fall, and any dead or diseased branches should be removed promptly.
  6. Wiring: Hemlock bonsai trees can be wired to shape their branches and trunk. Wiring should be done carefully and gradually, as the branches can be brittle and may break easily.
  7. Repotting: Hemlock bonsai trees should be repotted every two to three years, depending on their growth rate. Repotting should be done in the spring. As the tree gets older the repotting time will become longer as the tree begins to slow down.


In conclusion, hemlock is a fascinating and versatile plant with a rich history, physical characteristics, and traditional medicinal uses. However, it is important to note that hemlock is also highly toxic and can be fatal if ingested. As such, caution should be exercised when handling or consuming any part of the plant.
When grown as a bonsai, hemlock can be an excellent choice for bonsai enthusiasts who are looking for a tree with attractive foliage, interesting trunk structure, and adaptability to different growing environments. With proper care and maintenance, a hemlock bonsai tree can thrive and provide years of enjoyment.
Whether appreciated for its historical significance, physical characteristics, or potential as a bonsai tree, hemlock remains a plant that is both captivating and potentially dangerous. As with any plant or natural substance, it is important to respect its properties and handle it with care.

Leave a comment

Please note, comments need to be approved before they are published.

  • Brach Cutter + Scissor Bundle

    These are the 2 most essential tools in bonsai, so why not buy them together and save? Both tools are high quality Japanese Steel from one of the most trusted brands in bonsai. Click the image above to get your discount.

  • Essential Scissors Bundle

    In bonsai you will need a set of scissors to cut the foliage on top and the roots down below. Save when you buy both pairs with this bundle offer. Both tools are high quality Japanese Steel from one of the most trusted brands in bonsai. Click the image above to get your discount.

  • Protect Your Tool Investment

    When investing in high carbon steel tools it is wise to protect them with tool oil to maintain optimal performance. Save 10% when you bundle the tool oil and the applicator together. Click the image above to get your discount.

  • Cut Paste Bundle

    When we trunk chop or break branches during wiring it is best practise to get the wound covered straight away with cut paste or putty. Putty is used for larger wounds while paste is used for cracks, breaks and grafts. Get both today at a discount price when bought as a bundle. Click the image above to browse our range and select your pastes.

  • 100g Bonsai Wire Deal

    Wiring you bonsai trees will be a large part of your practise, make sure oyu have all the wire you need on hand and ready to go with our 100g bonsai wire deal. Add any 5 rolls to your cart and only pay for 4! Click The Image Above To Choose Your Rolls.

  • 500g Bonsai Wire Deal

    If you are a serious wiring machine and require a little extra wire on hand our 500g rolls are perfect, What makes them even better is if you add any 5x Rolls to your cart you will get $10 off. Stock up and be ready for any wiring job. Click The Image Above To Choose Your Rolls.

1 of 6
bonsai artist with bonsai tree

Author : Joshua Hooson

Joshua Hooson is an author and enthusiast of the art of bonsai. He has built his knowledge and understanding of bonsai through a combination of self-experience, lessons learned through hands-on practice, and extensive research. His articles reflect his passion for the subject and offer insights gained through his own personal journey in the world of bonsai. All the information provided in his works is a result of his own experiences and the knowledge he has gained through his studies. He is dedicated to sharing his love of bonsai and helping others grow in their understanding and appreciation of this ancient and beautiful art form.

Learn Bonsai Online With Josh