Canadian Hemlock – great privacy tree which  also tolerates shade.

Canadian Hemlock are a great choice for a privacy screen in sunny or shady locations. They belong to the Tsuga genus, and have a botanical name of Tsuga canadensis. They grow slowly, about one foot per year, to be large evergreen tree with flat needles, naturally airy shape, but can be pruned smaller and denser. They will grow more slowly in shade.

Hardiness Zones

Canadian Hemlock thrive in hardiness zones 3 through 6. In North Carolina, for example I only see them growing naturally in the mountains, where it is zone 6a. A good option for zone 6b or higher(warmer) and have a shady location to screenare Nellie Stevens Hollies  

Soil Types

These trees do not like dry or compacted soils at all. They prefer acidic soils that drains well. If your privacy screen is elevated and dry, possibly add a ring of mulch above the  tree's root zone and consider installing a drip irrigation system. Don't bank the mulch or dirt after planting up against the trunk itself, this is best advice for any species of tree. A sandy, clay and chalky soil with a ph of between 5.0 and 6.0 is ideal for planting Canadian Hemlock since it does best in moderately acidic soil. Canadian Hemlocks like a soil rich in organic matter--like peat moss or compost--that can hold moisture. If you plant in clay type soils, still add organic matter so the plant thrive. Sandy soils should also be conditioned with organic matter and watered regularly to have a nice plant.

Spacing

Twenty foot spacing is plenty wide to let them grow with no pruning or topping. Ten or Fourteen foot spacing is good for Canadian Hemlock privacy screens, if you plan to prune them and also top them before they reach 4 times whatever distance you spaced them. The zig zag pattern allows you to plant that far apart but get closure in ½ the time as a single row. Plant two parallel rows with the zig zag pattern, space them twelve feet on center along each row and staggered so there appears to be a tree every six feet. When each tree attains six foot width, the screen will begin to provide “closure”

Pruning and Watering

You can actually prune evergreens any time of year. If you prune in early spring, the new growth will appear and fill in any spaces you created during pruning. Watering Their root system should stay moist, but not wet, with frequent watering. All tree roots need to aspirate or breathe, so water at most every other day, not every day.

Pests - Hemlock Wooly Adelgid.

Canadian hemlock has one pest that does bother them, but is easily handled. The hemlock wooly adelgid is a small, aphid-like insect that hides inside a woolly sac. Check your Hemlock at least once a year, this will help prevent serious damage from this pest. The insect appears like a small pieces of cotton, and is found on the underside of the needles. October is the best time to treat these pests, using either insecticidal soap or horticultural oil. You can use a product called "Bayer Advanced 12 Month Tree and Shrub Protect and Feed II Granules ". It is available to nurseries under the name “Merit” usually in larger quantities. When this product is applied to the base of the tree yearly will keep the tree insect free. It has systemic action; just pour on the ground at the drip line of the tree, it will be absorbed by the root system so will protect the entire tree without spraying. The active ingredient is Imidacloprid. The label may say "not for sale to NY", always follow label instructions.

Canadian Hemlock

Canadian Hemlock is the best choice for a privacy screenin shady locationsin hardiness zones 6 through 3.