Small Trees for Small Spaces
Even if you have a small or very small garden, you can have a small tree. Trees come in a huge variety of sizes and shapes. And, much of their growing conditions can be manipulated to keep trees on the small side.
From a garden design standpoint, a tree helps to draw the eye upwards instead of drawing attention to the fence line. A small tree can act as a focal point, as a specimen, be part of a mixed border (you can underplant a tree with smaller shrubs and perennials), as a screen to mask unwanted views, and as a home to birds. Trees also provide natural cooling and reduce C02 emissions; learn more here.
Trees need space to grow. If you have a small front yard or back yard, don’t plant a big tree. A good rule of thumb to follow is: the tree canopy you see above ground is mirrored below ground by the tree's root system.
All trees are small when you plant them; you need to know how tall and wide the tree will be at maturity. Plant trees well away from the foundations of your house and the fence line (you don’t want to annoy the neighbours).
Hardwood trees tend to be slow growers and can also live a very long time. The most common hardwood species in North America are oak, maples, hickory, birch, and cherry. In other words, if you change your mind about the tree later, moving it is a big job; your only option then will be to cut it and plant a smaller tree.
A small tree in a small garden has to do double or even triple duty: take into account interesting foliage, flowers (if any), fruit or berries (for human or bird consumption), and interesting bark. In Canada, the winters are long and it is always great to gaze outside and see bark that has texture and colour against the bleak landscape.
In a small garden, you are probably better off with interesting foliage and interesting bark rather than spectacular flowers on a tree than only last a week, or so.
Think twice before planting a fruit tree
Many first-time urban gardeners are excited by the prospect of planting a fruit tree and picking their own fruit. Please inform yourself on the basics of orchards. Most fruit needs to be preventively sprayed, to guard against insects. For example, apple trees will be full of worms by the fall if unsprayed.
Maturing fruit is also a magnet for wildlife: raccoons, possums, and deer (if you live near a conservation area or preserved green space).
And, beware that when the fruit is ripe, you will have a glut on your hands and you have to preserve it, give it to friends, or let it rot on the ground. There is lots of clean-up required with fruit trees.
Small trees to investigate
Lily (or tulip) magnolias – grow to 15 feet tall and wide
Cornelian cherry dogwood – grows to 20 feet
Flowering crabapple (Red jewel) – grows to 20 feet (white flowers in May)
Golden desert ash – grows to 30 feet high and 15 feet wide
Pyramidal Mountain Ash (Sorbus aucuparia 'Fastigiata’) – White flower panicles in June and red fruit in the fall that attracts birds. Grows to 25 feet high with a spread of 10 feet.
Japanese maples – these come in upright and spreading habit varieties
Ivory Silk Japanese Tree Lilac – grows to 25 feet high and 20 wide (fragrant white flower panicles in June)
Eastern redbud – 30 feet high and 30 feet wide (deep pink flowers on bare branches in spring). Take a look at the ‘Hearts of Gold’ Redbud. Fabulous leaves. Lavender Twist Redbud (Cercis canadensis 'Covey') grows to just 6 feet high with a spread of 8 feet and has a weeping habit.
Venus Flowering Dogwood (Cornus ‘Venus’) – Height and spread of 20 feet. White flowers in early summer. Great fall colour and sculptural grey bark in winter.
How to keep trees small
Containerize the tree, even in the ground. You will have to check on the health of the root system of a containerized tree every couple of years. You may need to do root pruning. You will, in effect, be keeping a large outdoor bonsai tree.
Prune or shear trees to keep them small, but do not top. Topping the tree means cutting the leader, the main branch that determines the tree’s height. Learn why this is a harmful pruning practice.
Pleaching – Weaving the branches of the tree into itself. Learn about pleaching.
Espalier - Espalier is the ancient agricultural practice of controlling woody plant growth for the production of fruit, by pruning and tying branches to a frame. This is popular for fruit trees in France.
Pollarding – Pollarding is a pruning system in which the upper branches of a tree are removed, promoting a dense head of foliage and branches. Not all trees can take pollarding; dogwood, willow, and mulberry can withstand pollarding. All weeping mulberries, like the one below, have been pollarded. Gnarled and twisted branchwork provides winter interest.