Tsuga canadensis 'Pendula'
Canadian Hemlock, Eastern Hemlock
Type Tree, woody plant
Hardy range 4A to 7A
Height 50' to 75' / 15.20m to 22.80m
Spread 25' to 35' / 7.60m to 10.60m
Growth rate Slow
Form Weeping
Exposure Full shade to full sun
Persistence Evergreen
Bloom Color Green and yellow
Bloom Time Spring
Environment
This plant tolerates some drought and a little salt.
This plant will grow in dry soil.
Suitable soil is well-drained/loamy or sandy.
The pH preference is an acidic to neutral (less than 6.8 to 7.2) soil.
Leaf Color Green
Fall Color No change in fall color
Culture Notes
Hemlock transplants well balled-in-burlap due to a branched root system and will grow in moderately dry or moist, acidic soil but prefers moist, well-drained sites. Trees are often found in shaded ravines in their native habitat growing where roots have ready access to moisture. However, root rot and bark splitting are common on sites which are constantly wet. Some die-back can be expected after transplanting if irrigation is not managed just right. Many people have success locating the plants on a slight mound several inches above surrounding soil to help roots become established. Be especially careful not to plant trees any deeper than they were at the nursery. The top-most root in the root ball should be within an inch or two of the soil surface.
Despite its like for shaded landscapes, plants grow well in full sun in the middle and northern part of their range provided there is plenty of open soil for root expansion. This is not a tree to plant in a lawn in competition with turf unless a large area of mulch is maintained around the tree. Nitrogen fertilizer applications should be kept to a minimum to help keep insect attacks from woolly adelgid in check; these insects kill trees. This is the state tree of Pennsylvania. National champion is 165 x 38 feet in Tennessee.
Plants grown in full shade will be thin and will not produce the screening effect so characteristic of Hemlock in full sun or partial shade. This is a picky plant but well worth the extra effort to cultivate it. Canadian Hemlock is tolerant of shearing and can be used for large or small, sheared screens. Unfortunately, infestations of woolly adelgid have been severe in New England and in the mid-Atlantic states and this may limit their use in these areas.
Tree establishment specifications
Choose good quality trees for planting. The most common cause of young tree failure is planting too deep. In most instances, the point where the top-most root in the root ball originates from the trunk (referred to as the root flare zone or root collar) should be located just above the soil surface. You may have to dig into the root ball to find the root flare. If there is nursery soil over this area, scrape it off. Never place ANY soil over the root ball. The planting hole should be at least twice the width of the root ball, preferably wider because roots grow best in loose soil. In all but exceptional circumstances where the soil is very poor, extensive research clearly shows that there is no need to incorporate any amendments into the backfill soil. Simply use the loosened soil that came out of the planting hole. Simply planting with the topmost portion of the root ball slightly higher than the surrounding soil might still install the tree too deep - be sure to locate the root flare.
Weed suppression during establishment is essential. Apply a 3-inch thick layer of mulch to at least a six-foot diameter circle around the tree. This area should be at least two feet in diameter for each inch of tree trunk diameter and maintained during the establishment period. Apply a thinner layer of mulch directly over the root ball but keep it at least 10 inches from the trunk. This allows rainwater, irrigation and air to easily enter the root ball and keeps the trunk dry. Placing mulch against the trunk and applying too thick a layer above the root ball can kill the plant by oxygen starvation, death of bark, stem and root diseases, prevention of hardening off for winter, vole and other rodent damage to the trunk, keeping soil too wet, or repelling water.
Regular irrigation after planting encourages rapid root growth that is essential for tree establishment. Trees provided with regular irrigation through the first growing season after transplanting require about 3 months (hardiness zones 9-11), 6 months (hardiness zones 7-8), or one year or more (hardiness zones 2-6) per inch of trunk diameter to fully establish roots in the landscape soil. Trees in desert climates may take longer to establish. Trees that are under-irrigated during this establishment period (and most trees are) often require additional time to establish because roots grow more slowly. Be prepared to irrigate through the entire establishment period, especially during periods of drought.
Irrigation also helps maintain and encourage the desirable dominant leader in the tree canopy on large-maturing trees. Instead of a dominant leader, trees that are under-irrigated during the establishment period often develop undesirable, low, co-dominant stems and double leaders that can split from the tree later.
Unlike established plants, which do best with deep, infrequent irrigation, research clearly shows that recently transplanted trees and shrubs establish quickest with light, frequent irrigation. For trees planted in spring or summer, provide one (cooler hardiness zones) to three irrigations (warmer hardiness zones) each week during the first few months after planting. Daily irrigation in the warmest hardiness zones provides the quickest establishment. Following the initial few months of frequent irrigation, provide weekly irrigation until plants are fully established. With every irrigation, apply one (cool climates) to two (warm climates) gallons of water per inch trunk diameter (e.g. 2 to 4 gallons for a 2-inch tree) over the root ball only. In most landscapes that receive more than 30 inches of rain or irrigation annually, if the mulch area is maintained weed-free, irrigation does not need to be applied outside of the root ball. Never add water if the root ball is saturated.
In cooler hardiness zones, in all but the driest years, irrigation of spring- and summer-planted trees usually can be discontinued once fall color has begun. Irrigation of fall planted trees, however, should be continued until foliage has dropped from the deciduous trees in the region. In warmer climates, irrigate fall-and winter-planted trees as described for the spring- and summer-planted trees.
In drier, desert climates there is benefit to be gained from applying additional irrigation outside of the root ball area. This is best done by making a large diameter berm four to six inches high, then filling it with water so it percolates into the soil. For the first two years, irrigate twice each week through the spring, once per week in summer provided monsoons arrive, and twice each week again in fall if it remains warm. Taper off watering to once or twice each month in winter and resume twice weekly next spring. For years three to five, water twice per month in spring, summer, and fall and once or twice per month in winter. During years five through seven, water once every three weeks in warm weather and once every six weeks in winter. After this, the drought-tolerant desert trees should be able to survive on natural rainfall.
Trees with good, strong structure need no pruning at planting, except to remove broken twigs. Do not remove branches to compensate for root loss - research has shown that this can be detrimental to establishment.
Spring transplanting best
Balled-and-burlapped and bare root trees recover best when transplanted in late winter or early spring in the cooler portions of North America. This usually corresponds to the initiation of root growth.
Pests, Diseases and Damaging Agents
Pests: Woolly adelgid, scales, weevils, bagworm, mites, sapsucker
woodpecker, loopers. Woolly adelgid and scale infestations can devastate a planting and kills many trees in their native habitat and in landscapes in the mid-Atlantic states and in other places. Insects increase in number on plants fertilized with too much nitrogen.
Diseases: Needle rust, cankers, non-parasitic bark splitting on heavy, poorly drained soil.
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