I trust all is well with you and your family, friends and acquaintances.
We live on the 12 floor of a downtown Toronto condo with a west facing balcony. Our balcony is only open on 1 side, i.e., the west facing side and gets sun from approx. 11am to 8pm.
We are looking for a dwarf tree or shrub with the potential to thrive in this very hot, sunny environment. And of course, the normal overnight temperatures of Toronto.
Hello and thank you for posting your question on the Toronto Master Gardener ASK site. How lucky you are to have a sunny west facing suite! This opens up countless possibilities for a balcony garden. First however, before you spend a penny on any plants you must ensure that you are properly set up for their care.
Regulations – Make sure that there are no weight restrictions for your balcony, as even a small shrub or tree will eventually be very heavy.
Containers – You may want to look at fiberglass or a sturdy plastic container as clay or concrete will be too heavy. At the same time, you want to make sure that your container is weighted enough that it does not blow around in windy weather. I would stay away from metal, as in your sunny situation it will become extremely hot and will overheat the plant’s roots. You will need to insulate your planter for overwintering, so get the largest size you can, to accommodate this as well as the growing roots of your tree. Whatever you choose, make sure that it has holes ensuring proper drainage.
Watering – Watering will be key to ensuring the success of your tree or shrub. Container grown plants will require more water than those grown in the ground, as the sun and wind quickly dry out your soil. Also, you will not get adequate rainfall due to overhanging balcony or roof. I would make sure to invest in a watering system that will provide a constant supply of water, even when you are not at home.
Soil – Important to use a “soil less” planting medium. Regular soil will become rock hard in a container. Look for a medium that is called “Veranda” or “Container”. A quality garden center will assist you in choosing a good mix. As these mixes are very low in nutrition, you will need to fertilize your plant regularly to replace what is available in nutrition rich garden soil.
Plant selection – As a rule of thumb when gardening above ground you should select plants hardy to two zones lower that your location. So, in Toronto look for plants hardy to zone 4, this is two zones lower than Toronto which is zone 6a. Also try to stay away from trees or shrubs with large leaves. Wind will be a factor on the 12th floor.
Here are some suggestions:
Spirea – Dozens of varieties are available of this easy-care shrub. Look for diminutive names such as “nana” or “little prince” to denote a compact variety. These are extremely winter hardy and enjoy a sunny location. You will need to keep soil moist, and prune yearly for a tidy rounded shape
Lilac (Syringa) Lilacs are excellent candidates for your location, they like a sunny location and tolerate windy conditions. Korean lilacs such as “Miss Kim” with its lovely rounded shape are perfect for growing in containers.
Serviceberry (Amelanchier )is a great small to medium tree. It provides year-round interest, delicate white flowers in spring, red berries in summer and excellent fall colour. Shadblow serviceberry forms a multi – stem shrub that can grow up to 20 feet tall. A. laevis ‘Cumulus’ is a smaller more compact cultivar which grows to 10 feet.
Similar to Serviceberry, but smaller is Chokeberry (Aronia melanocarpa). It gets its name from it is technically edible but bitter berries. It is a wonderful “tough as nails “shrub; drought tolerant, tolerant of compacted soils and has good winter hardiness.
Another tough plant is Ninebark (Physocarpus) It has small white flowers in the spring but is best known for its gorgeous foliage. This shrub is very winter hardy and is somewhat drought tolerant once established. “Diablo” is one of the most common, but look also for the brilliant “Ginger ale, Coppertina and Amber glow” varieties.
You might also consider an evergreen. Conifers are not as showy as flowering shrubs, but they provide little bit of green even in the deepest winter and some varieties make excellent container trees.
Juniper (Juniperus) – There are dozens of different Junipers, with many available shapes and sizes. Look for one that is advertises prostrate, spreading or mounding. One that is excellent in containers is J. squamata “Blue Star” it will only grow up to 4 feet. J. chinensis will grow a bit taller but with a graceful arching form and pretty mint green colour.
Like Junipers, False Cypress (Chamaecyparis) offers much choice in size and colour. Look for C.obtusa “Nana Aurea” or C.pisfera “Filifera Aurea” for attractive gold foliage and good winter hardiness.
I cannot fail to mention the very popular Alberta Blue spruce (Picea) it is almost made for containers, with its hardiness and conical shape that requires little to no pruning.
I hope that you will find these suggestions helpful. I wish you all the success for your balcony garden.
Here is some additional information on balcony gardening: