Canadian hemlock trees are shade-tolerant and make very little mess, keeping their graceful look throughout the seasons. Plant Canadian hemlock in the early spring. Plant the trees 30 to 40 feet apart. These shallow-rooted trees need protection from the wind, or else you might return home one day after a storm only to find your tree lying on the ground.
Light
Unlike many large trees, Canadian hemlocks grow best in full to part shade and will tolerate full sun in cold northern climates. Their sunlight requirements provide quite a bit of flexibility if you live in a cold climate (USDA zones 3 to 5).
Soil
These trees require soil that is moist but has good drainage. They prefer a loamy, acidic soil.
Water
Hemlock trees require a fair amount of water. They can tolerate less favorable conditions (partial sun in average soils of alkaline pH) if sufficient supplemental water is given during the dry periods of summer, but the soil must be well-drained. This tree does not tolerate standing wet soil nor prolonged periods of drought. The best method of watering is slow watering once a week. Start the watering process with a general spray of the trunk and leaves. This will help to wash away insects and pollution residues. Then, place the garden hose at the base of the tree and allow it to run for 15 to 20 minutes—this will distribute the water to the root system effectively.
Temperature and Humidity
This tree grows in regions with cool, humid climates. In the northern areas, January temperatures average 10 degrees Fahrenheit and July temperatures average 60 degrees Fahrenheit. Precipitation ranges from less than 30 inches.
Fertilizer
This tree needs a well-balanced fertilizer (10-10-10) about once a year. Do not add fertilizer to your hemlock right after transplanting because it can burn the root system and it could lead to the death of the tree. Wait a few months until the tree is established.
Types of Canadian Hemlock
Many cultivars of Canadian hemlock have been developed for landscape use, they have been bred for circumstances where a taller tree is not suitable.
‘Gentsch White’: This dwarf shrub-like cultivar has white or cream variegated foliage and a round, globe-like shape. It matures at only five 5 in height (by about the same width).‘Aurea Compacta’ (also known as ‘Everitt’s Golden’): This bright golden-colored cultivar has an upright habit and reaches 5 feet in height, with a spread of only about half that.‘Sargentii’ or ‘Pendula’: Also known as weeping Canadian hemlocks, these two cultivars are large shrub forms with an attractive weeping or arching habit. They reach about 12 feet tall or more (and can be twice as wide).
Pruning
Canadian hemlock trees do not need much pruning unless limbs are damaged by weather or disease. Prune in spring and early summer because the tree is in active growth and will easily recover. Avoid pruning hemlock trees in fall or winter because the tree will become confused, returning to active growth instead of going dormant to withstand the winter. Compact cultivars, which are essentially shrubs, are commonly used as privacy hedge plants or in foundation plantings. If you begin pruning them when young, they are fairly easy to shape.
Propagating Canadian Hemlock
Canadian hemlock cuttings can be taken from semi-hardwood branches for propagation in late summer.
How to Grow Canadian Hemlock From Seed
Sow hemlock seeds in the fall so they can spend the winter outdoors. The chill of the long cold winter period (cold stratification) is necessary for seedlings to emerge in the spring.
Potting and Repotting Canadian Hemlock
Canadian hemlock is a tall and wide tree meant to be planted in the landscape. Even dwarf varieties are not suitable for growing in containers, except when grown as a bonsai.
Overwintering
As a tree that is native to North America and whose northern habitat range runs along the southern border of Canada, Eastern hemlock is a very cold-hardy tree that does not require any winter protection.
Common Pests & Plant Diseases
Canadian hemlocks have two major enemies the wooly adelgid insect and white-tailed deer. Hemlock woolly adelgid (Adelges tsugae) is an invasive, tiny sap-sucking insect (a relative of the aphid) that has become a threat to the hemlocks in their native areas of eastern North America and home landscapes. Infested trees have white woolly masses at the base of the needles on the undersides of the twigs. Treatment with pesticides is available but controlling an infestation is extremely difficult. Canadian Hemlocks can also be damaged by browsing deer. If you have a heavy deer population in your area, perhaps seek an alternative tree or shrub with better deer resistance.
