Whether you choose a tree or shrub for the colour of its leaves, to provide shade for your favourite sitting area or because of its fragrant spring flowers or fresh fruit, a tree or shrub is a long-term investment in a beautiful green space. Although it will one day grow into a majestic part of nature, every tree and shrub will need a bit of help from you to get to that point.
How Much Water
Watering is the single most important step you can take to ensure the health of any plant. If you have an irrigation system installed, it is not sufficient to water trees (an irrigation system is sufficient to water shrubs). Supplementary watering must be done manually with a garden hose to ensure trees have enough water. Trees generally require 1gal (4.5L) of water per foot of height every week. Shrubs generally require 1gal (4.5L) of water per foot of height or spread (whichever is greater) every week. Deep and infrequent watering (once a week) is the best to encourage the roots to grow deep.
Watering Best Practices
When watering, wet the soil at the base of the plant in a 2 foot radius around the truck. Move the hose around the area and try to avoid creating streams of water that erode the soil and carry water away from the plant. If this happens, the soil in oversaturated and cannot absorb any more water. Move to another tree and return later once the water has soaked into the soil completely. Repeat as necessary until the tree or shrub has received the required amount of water. You can also attach a nozzle to your hose to reduce the flow rate and allow the soil to absorb the water at a slower pace to avoid runoff, but keep in mind that you will have to water for longer to deliver the required amount of water.
Newly planted trees need to be watered at least once a week for the first year after planting. You may need to adjust the frequency of watering depending on the season and weather.
Summer / Dry Periods
During the heat of the summer or an extended period (2 weeks) with little or no rainfall, an additional watering every week may be necessary. At a bare minimum, any rainfall must exceed ¼” (5mm) to have any effect on a tree or shrub. Any amount less than this does NOT help. As a rule, 1 day after a watering you should be able to stick a finger 2-3” into the soil at the base of a plant and have it come up damp. If it is dry, more water is required.
Spring / Fall / Wet Periods
Ensuring your tree or shrub has enough water is the most important thing you can do to make sure your plant stays healthy. Watering deeply once a week will provide your plant with enough water and help the roots grow deep.
During cooler months, or an especially rainy stretch, trees will need to be watered less frequently. If the soil at ground level is moist, the tree or shrub is sufficiently watered. If it is dry, do the finger test to check if the plant needs water.