Everyone loves evergreen trees, but unfortunately needle-evergreens, or conifers as they are more correctly called, almost all need sunny locations to do well. So when we meet a conifer that will not only tolerate shade, but actually prefers it, this is a plant to take notice of. The Canadian Hemlock is such an evergreen, thriving in the shade of deciduous trees or on the north side of a home and bringing its special charm to any shady location. Unlike many other evergreens, it has foliage that is soft and pleasant to touch, so it can be planted where it is brushed against without causing prickles. It has another virtue too as it can be clipped and pruned as needed and makes an excellent evergreen hedge for a shady location.
Canadian Hemlock, Tsuga canadensis, is native to south-eastern Canada and the north-eastern United States from Maine through the Appalachians to Alabama. It grows in mature woodlands beneath deciduous trees. Its timber is soft and has limited uses. It is found mostly in damper locations and it is not very drought-resistant. It is not the plant the philosopher Socrates was poisoned with and in fact it is in no way poisonous, so it can be safely grown around children. Our Canadian Hemlocks are grown from seed taken from quality trees specially selected for their elegant form, rapid growth and good health. Beware of cheaper trees that will often be of poor quality.
Growing Canadian Hemlock Trees
Canadian Hemlock can be grown as a specimen tree in sunny locations in cooler areas or beneath large deciduous trees in warmer regions. It grows steadily into a large tree with elegant drooping branches sweeping down to the ground in a broad conical shape. It has small, soft needles in double rows along the twigs. It is also an excellent hedge plant for shade, particularly because being evergreen it will provide privacy all year round. It has a soft, dark-green appearance and makes a perfect back-drop for woodland plants like azaleas, camellias and hydrangeas, which also prefer the same damp conditions.
Canadian Hemlock is hardy from zone 3 to zone 7, so it is a prime choice for cooler, rainier areas of the country, where it is a very suitable plant to grow as a specimen or as a hedge. It can be grown in full sun in zones 3, 4 and 5, but in warmer zones it should be protected from sun, especially the hot afternoon summer sun. This tree will grow best in moderately rich soil with a good organic content and does not need well-drained soil, in fact it will do best with a steady supply of moisture. It prefers acid soils but will grow well on all kinds of soil except those which are very alkaline.
Size and Appearance
The Canadian Hemlock grows into a large tree and some trees have been recorded at well over 100 feet tall, but this takes many, many years. Most trees found in gardens are 20 to 70 feet tall if left un-pruned. It has small, dark-green and slightly glossy leaves never more than an inch in length and usually smaller, giving the tree a delicate, airy appearance. Un-pruned it will grow with a central trunk, with long, sweeping side branches that hang down as the tree grow wider. A mature tree may be 25 to 35 feet wide. With pruning it is not difficult to keep a narrower tree if desired, and it can also be clipped into neater conical shapes if desired.
Using as a Hedge
Because of the ease and adaptability to pruning, Canadian Hemlock is an excellent choice for hedges in shade. To plant a hedge, place the plants 3 to 4 feet apart in an even row and place the row 3 feet from a fence or wall. Canadian Hemlock hedges can be kept just 3 or 4 feet tall, or grown into tall hedges 15 feet high, depending on your needs. This tree is a little slower growing than some other hedging plants, but it is the only tree that will form a good hedge in full-shade. Feed your hedge regularly with an evergreen fertilizer each spring and through the growing season to get the maximum growth. Stop feeding at the end of August to prevent possible cold injury.
Care and Maintenace
Prune your Canadian Hemlock hedge in late winter, shortly before new growth begins and again in early summer. In very cold areas, prune your hedge only during mild weather. Start pruning lightly as soon as you have planted your hedge – do not wait until it has grown large or you will find it hard to develop a dense structure. Always prune the top a little narrower than the bottom so that the face of the hedge leans in slightly. This will make sure that light reaches the lowest parts and you keep dense foliage right to the ground. Frequent light pruning is better than occasional hard cuts and you will develop a lovely dense texture that way. Like other conifers, Canadian Hemlock will not sprout from bare branches, so never cut thick stems that do not have leafy shoots on them.