Adding Trees to the Garden

Article: Maria MacRae

Photograph: Amy Walters, iStockphoto

Trees are the bones of any garden. Not only do they give structure to the garden, but they also influence growing conditions for other plants by affecting light and moisture availability. They are one of the best choices for creating wildlife habitat by providing shelter, nesting sites and food sources. Therefore, the first decision in choosing plants for your garden should be what trees you want to add.

The first step in successful tree planting is to decide on the type of tree to plant. Examine the site carefully and think about your purpose in planting the tree. Consider the following:

•The size of the site will determine what kinds of trees can be added. Is there a lot of overhead space or are there utility lines above the site? Is the area large? Determine the distance to any building, driveway, sidewalk, streetlight or other structure. Is the tree likely to interfere with the sight lines of nearby traffic intersections? What volume of soil is available for the tree’s roots? Are there any underground utilities in the area? Remember that a tree spreads as much underground as its canopy does above.
•Find out the mature height and width of any tree species you are considering. Will it fit in your site?
•What are the characteristics of the site? Determine how much sun the tree will get. Also, look at soil pH and texture, drainage, exposure to winter winds, and soil depth. Choose a tree species that matches the characteristics of the site. If the site is very dry and you choose a tree that prefers very moist areas, it won’t survive for long.
•In urban areas, it is important to consider the tree’s exposure to salt from winter roads and snow clearing, air pollution, drought and compacted soil. You may also need to consider branch strength to avoid damage during winter ice storms. Some tree species are better adapted to the stresses of urban life. Your municipal parks department may have suggestions for good trees for your urban area.
•What is the purpose of your tree? If you hope to attract wildlife, consider what food and shelter the tree will provide. Will it be a source of seeds, nuts or fruit? Does it bloom in spring or summer to provide nectar for butterflies and other pollinators? Is there already year-round shelter in the vicinity or should you consider adding some evergreens?
•How much of your yard will be shaded by the tree? Will the new shade affect other plants in your yard?
•Trees, if placed to decrease the amount of sunshine hitting your walls, roof and windows, can lower your energy bill in the heat of summer by minimizing your need for air-conditioning. The ideal tree for this purpose is tall with a wide umbrella-shaped crown to provide maximum shade. Deciduous trees are the best because they will provide shade in the summer, yet allow the sun through in the winter to provide heat when it’s needed. If saving energy is one of your goals, place shading on the west wall of the house to protect it from the hot afternoon sun. Trees that provide summer shade from morning sunshine on the east side of the house can provide even further energy savings. If you are planting on the south side, ensure that shade from tree trunks and branches won’t interfere extensively with winter sun reaching south-facing windows.
•To cut those winter heating bills, dense trees planted along the northwest side of the house will protect the house from frigid winter winds. Evergreens, with their impenetrable winter foliage, are the only choice for this purpose.
•Hardiness is an important consideration. How will the tree you select survive in your local climate? If you choose a tree that is native to your region and place it in an appropriate spot, hardiness should not be an issue. If you choose a non-native species, avoid any invasive species such as Norway maple and both glossy and common buckthorn.
•Try to choose a number of different tree species for your property. If you plant a diversity of trees, you can provide habitat for a greater variety of wildlife and limit damage from any one insect infestation or weather disturbance.

Once you have chosen your tree(s), the next step is planting. Trees will be a focal point in your garden for decades to come so it is worth paying a little extra attention to make sure they make it through that first period of adaptation. Once well established, they should be able to take care of themselves.

Follow these important steps when planting:

•The best time for planting bare-root trees is early spring (before the leaf buds open) or late fall (after deciduous leaves have fallen). Potted trees have a wider window of opportunity for planting, but try to avoid periods of extreme heat and drought, and ensure that fall plantings allow enough time for adjustment before frosts start.
•Choose early mornings, evenings and rainy days to do the work. Avoid planting seedlings under the hot sun.
•Keep the roots moist at all times, but don’t immerse them in water. If you must store them, do so in a sheltered, cool, shaded spot. Bare-root trees and seedlings should be planted as soon as possible.
•In the case of seedlings, remove a patch of sod about 3 to 6 centimetres wide and dig a hole 3 to 10 cm deep for each one — just deep enough to allow the root of the plant to be buried up to the root collar (where the roots join the stem). There should be enough space to spread the roots out without bending or curving them around.
•In the case of larger bare-root trees, you can build a cone-shaped mound in the centre of the hole that will allow you to spread the trees roots out over the mound.
•For large plants, the hole should be the same depth as and two to three times the width of the root ball. Allow at least 15 cm of extra space around a root.
•Leave a radius of at least one metre between plantings. Consult an expert on the spacing required between each species of tree or shrub.
•Use the soil that was removed to refill the hole. Break up any hard-packed clumps.
•Add the soil gradually. Gently tamp the soil or add water to eliminate any air pockets. Be sure not to compact the soil. Add more soil and water again. This step ensures that air pockets are filled with healthy soil. Do not press very wet soil or it will become too compacted.
•Water the tree immediately. Add the water slowly, letting it soak in before adding more.
•Stake trees only if absolutely necessary — for instance, if the site is very windy. Be sure to use soft, wide fabric strips and tie loosely to allow some movement. Gradually loosen the ties over time so the tree can develop its own strength.
•Ensure your tree has adequate water for the first few years. Start with frequent watering and gradually lengthen the time between waterings. Water requirements will vary depending on the size of the tree, soil type, time of planting and amount of rainfall. Generally, the smaller the tree at planting the more quickly it will adapt. Ask your supplier for specific advice for your area and the particular tree.
•Prune only to remove dead or broken branches.
•A layer of wood chips or other mulch material around the tree or shrub will keep the tree’s roots cool and moist, prevent soil erosion and weed growth, and protect the tree’s trunk from lawn mowers and trimmers. The tree should be mulched as far out as its drip line, but be sure to keep the mulch 15 cm back from the tree trunk to discourage access by mice. To break up large areas of mulch, add forest plants such as Solomon’s seal, ferns, wild ginger or foamflower.
•Continue weed control until the tree is big enough to compete with weeds. Keep watch for this problem for at least two years.
•Surround trees with fencing to protect them from any grazing animals or human damage.
•Mesh “socks” or covers can be placed over the leading shoots of young conifers to protect them from grazers.
•Protect the trunks of your deciduous trees from rodents in winter by encircling them with tree wrap or chicken wire. You can also use a length of plastic corrugated and perforated drain pipe (available at hardware stores). Make sure you choose a pipe is wide enough around to leave space between the tree and the pipe.

If you take care of your new trees until they can take care of themselves, they will return the favour by giving you shade and cool air on hot summer days and shelter from wind on those chilly winter days.