Posted by Brent Wilson on 3/14/2023 to Fertilizing & Watering Tips
When planted right and in the right spot, Canadian Hemlocks, scientifically known as Tsuga canadensis, are very easy to grow.
Shade can be a challenge for gardeners, but the Canadian Hemlocks are one of a few coniferous evergreen plants that perform well in part to full shade. Their flat, needle-like leaves provide a unique texture and contrast in the landscape.
Here's a breakdown of what you need to know regarding planting and caring for Canadian Hemlocks...
Canadian Hemlocks prefer a moist but well-drained soil of average fertility. They prefer sandy loams often with an abundance of ground or coarse rocky material, but adapt to a wide range of soils. As with so many other ornamental plants and trees, constantly wet soil due to poor drainage can and often will causes root rot and other harmful plant diseases.
How To Test Soil Drainage
If you are uncertain about soil drainage in the area you intend to plant, it's well worth taking the time to test the drainage in the planting area before planting. To test soil drainage, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, may signal potentially dry site conditions. A slower rate indicates poor draining soil and is a caution you need to improve drainage, plant in a raised mound or bed, or look for plants that are more tolerant of wet or boggy conditions.
Canadian Hemlocls grow best in an acid soil ranging between 4.0 to6.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
How To Test Soil pH
Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline.
If you're unsure about the pH of your soil, and whether or not it's suitable for growing Canadian Hemlocks, it's a good idea to test the soil pH in the planting area. You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Learn More: What is Soil pH and How To Adjust It?
Canadian Hemlocks will grow in part shade to full shade. Morning and evening sun are okay but avoid direct sunlight during the midafternoon hours. will tolerate full sun in regions that have cooler summers, but prefers part shade conditions in hot areas. They grow remarkably well and look their best in a woodland environment.
Planting A Canadian Hemlock
Start by digging your planting hole at least two to three times as wide and only as deep as the height of the root ball of your plant. The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp.
Depending on the type, fertility and porosity of the soil in the planting area you might need to mix in a soil amendment to the native soil removed from the planting hole. When planting in dense clay or other compact soils it is beneficial to thoroughly mix in some good organic matter such as bagged top soil and/or a good planting mix at a 25-50% ratio with the soil removed from the planting hole. When planting in very sandy or quick-draining soil mixing in some top soil and/or compost will help to retain moisture in the soil.
Be careful not to damage your Canadian Hemlock when removing it from its nursery container. It's best to cut the container away.
If you are planting in well-drained soil, set your plant in the planting hole so that the top edge of the root ball is at or slightly above ground level to allow for settling. If your soil is moderately drained, meaning it drains slowly after rain, the top of the root ball should be 2 inches or more above ground level, as shown in the illustration below. If necessary, add some backfill soil mixture to the bottom of the hole to achieve proper planting height.
Note: If the soil is poorly drained (constantly soggy or wet) take measures to improve drainage or select a different plant species tolerant of wet soils.
After setting your Hemlock in the planting hole, use one hand to hold the plant straight and your other hand to begin back-filling your soil mixture around the root ball, tamping as you go to remove air pockets. When you have filled the hole to the halfway point you can soak the soil. Then continue back-filling to the top edge of the root ball. If you are planting the root ball higher than ground level, as shown in the illustration above, taper your soil mixture gradually from the top edge of the root ball to the ground level. To avoid suffocating your plant, avoid placing any soil on top of the root ball.
Step 6 (Optional)
When planting your Hemlock in a site far away from a water source, and in well-drained soil, you can use remaining soil mixture to build a water retaining berm (catch basin / doughnut) that is 2 inches or so high around the outside perimeter of the planting hole. This basin will help to collect water from rainfall and irrigation, which helps to reduce the need for hand-watering. The berm can be removed after the first growing season.
Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost, you can water your newly planted Hemlock with a solution of Root Stimulator, which stimulates early root formation and stronger root development, reduces plant shock, and promotes greener, more vigorous plants.
To conserve moisture and suppress weed growth, apply a 1 to 2" layer of cured, shredded or chipped wood mulch or pine straw around the planting area. Avoid the use of freshly chipped wood for mulch until it has cured in a pile for at least 6 months, a year is better. Avoid placing or piling mulch directly against the base of your plant as this could cause the bark to rot.
Caring for A Canadian Hemlock
Canadian Hemlocks are easy to grow and care for. Below are some helpful care tips that will have you growing them like the pros.
How To Fertilize Canadian Hemlock
Canadian Hemlocks are not heavy feeders but will benefit from fertilizer to maintain good foliage color and support growth and overall health of the plant. Feed as directed on the product label with a granular shrub & tree type fertilizer or organic plant food.
How To Water Canadian Hemlocks
Canadian Hemlocks prefer a moist but well-drained soil. They are moderately drought tolerant when established but will appreciate supplemental water to keep the soil moist during summer drought. As with so many other ornamental shrubs and trees, they will not tolerate constantly wet soil conditions or standing water, which can lead to root rot and other harmful plant diseases. So be careful not to over-water them!
At Planting Time
Immediately after planting deep soak the soil in the planting area to a depth equal to the height of the plants root ball. For an extra boost, to stimulate early root formation and stronger root development, you can also water you newly planted Hemlock with a solution of Root Stimulator, which reduces transplant shock and promotes greener, more vigorous plants. When planted during the winter dormant season plants will require less water. So, be extra careful not to overwater during winter!
During the First Growing Season
In average garden soil you should not have to water your newly planted Hemlock every day. More often than not, this causes constantly soggy soil conditions that can lead to root rot and other harmful plant diseases. In the absence of sufficient rainfall, water only as needed to keep the root ball and surrounding soil damp to moist.
Note: Keep in mind that deep soaking less frequently, and allowing the soil to dry out somewhat before watering again, is much better than splashing just a little water on the plants every day. Hemlocks planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!
Established Hemlocks will tolerate short dry periods. That said, during drought, especially in summer, they'll appreciate some supplemental water to maintain a moist soil.
Note: When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliage diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil moist, not wet.
Pruning A Canadian Hemlock
Canadian Hemlocks do not require pruning. That said, they respond well to an annual light shearing in late winter, before new growth begins to emerge, to control size or for shaping purposes. Damaged or dead stems or branches can and should be removed as they appear.
Plant Long & Prosper!
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