"To me the Canadian hemlock is the most beautiful evergreen tree that grows wild or under cultivation in all of New England. This is a "grand" native plant with soft evergreen needles on arching branches. The needle is 1/2 to 3/4 inch long and flat with a rounded tip, making it soft to touch. The top of the needle is dark green with a glossy finish. The bottom side of the needle has two silvery stripes running from end to end. When the wind blows, the underside of the needle becomes visible and makes the plant almost shimmer as it sways with the wind.
The Canadian hemlock grows in a rounded pyramidal shape. The new growth gives the tree a soft and almost feathery look. The plant is always thick and will hold inner foliage for many years, making it a wonderful privacy plant or noise barrier plant. The hemlock will also keep needles on the lower branches, right to the ground, unlike many evergreen trees as they mature and grow tall. When allowed to grow naturally and not pruned, the hemlock will grow to 70 feet tall and 25 to 35 feet wide.
Canadian hemlock looks great on your lawn as a single plant or in groups with underplantings of large leaf evergreens such as holly, rhododendron and azaleas. When planted on 10-foot centers, these plants will quickly grow together, creating a wonderful hedge. Prune the front and back of the hedge to control the width of the plant but not the sides. This will help fill in the space between plants faster. Once they fill in, prune both the front and back. The height is up to you--from 6 feet to the clouds. To control height, prune during March or April before the new growth starts. This way the new growth will fill in any spaces you open up during pruning, and the new growth that develops will keep the plant soft-looking, even though you have cut the plant like a wall.
Hemlocks will grow in sun or shade but must have a soil rich in organic matter--like compost or peat moss--that is able to hold moisture. When planting in clay type soils, add organic matter to improve the drainage, and the plant will do well. Sandy soils, like those on Cape Cod, must be conditioned with organic matter and watered regularly to have a nice plant. Hemlocks prefer a soil that is acid so do not add limestone near the plants!
The Canadian hemlock will make a small brown cone 1/2 to 3/4 inches long on new growth, dangling down from the tips of the branches with the point at the bottom. When there are many cones noticeable on the plant, they look like Christmas ornaments decorating the tree. Birds of all types love this tree, as it makes a great nesting plant. During the winter, the birds that stay around can hide in the thick foliage and stay out of the fury of the storm. Planted in an area where you feed the birds, the hemlock is perfect as birds can check out the feeding area for the neighbor's cat before they fly to the feeder.
When planting hemlocks, use plenty of peat moss or compost and water two time a week. Use a plant root stimulator like New Plant Thrive or Bio-Tone that contains mycorrhizia. This will increase root development much faster. Hemlock has one problem in Southern New England and south. A little insect called "wooly adelgid," that looks like small pieces of cotton, develops on the underside of the needles. Thanks to Bayer Lawn and Garden research, a product called "Tree and Shrub" applied to the base of the tree yearly will keep the tree insect free. It works systemically; just pour on the ground at the base of the tree and it will move right up to the top of the tree without spraying. Best of all, you can do it yourself--saving money. One application will last one year. Feed young plants yearly with Holly-Tone or Acid Adoring fertilizer. As you travel into Northern New England, you will see the Canadian hemlock growing with pines, spruces, maples and oaks in perfect harmony. The cold winters keep the wooly adelgid away in Northern growing areas, or the forest would have some real problems with this insect. This is a GREAT plant for your property."