Caller wants to grow an olive tree in his apartment, wonders if it is feasible to do so in Toronto, and where to get seeds/trees.
Olive trees (Olea europaea) are hardy to zone 8 or higher. As a houseplant, a dwarf variety of olive, which can grow to 1.8 metres (6 feet) in height, is recommended. These can be pruned to keep them a manageable height.
As to where to find the plant, try your local nursery; we are not permitted to provide specific recommendations on where to purchase plants. Ontario’s Ministry of Agriculture, Food & Rural Affairs has a website entitled Fruit Tree Nurseries in Ontario which provides the names & contact information for several nurseries. These mainly relate to trees to be grown outdoors, e.g., peaches, apples, etc., but these experts may be able to help you source an olive tree to grow in your apartment.
Note that pits from olives that have been cured (like we purchase from the grocery store to eat) will not germinate. Even if you have access to fresh olives – i.e., can pick the fruit in early autumn directly from the tree, the germination rate is low. So your best bet is to purchase a small plant.
Once you have your little olive tree in hand, make sure it gets at least 6 hours of direct sunlight each day. Ensure the leaves do not touch the window glass, as this can burn them. And keep them away from heat vents and radiators.
Fill a large container half full with a potting mix that drains well, e.g., one that contains sand. Place the tree in the container and add potting mix, making sure it is planted no deeper than in the original pot. Water thoroughly. Check the soil periodically and water thoroughly when the soil is dry to a depth of 2.5 cm (1 inch) – check with your finger. Be patient with the olive tree, it will grow slowly during the autumn and winter, don’t overwater! But don’t let the soil dry out completely, either.
Olive trees can tolerate relatively dry air, so there is no need to spritz yours with water. In autumn and winter, fertilize once a month with a balanced (houseplant) fertilizer (e.g., 20-20-20). Starting in spring, feed twice a month or use a timed-release fertilizer. Your olive tree likely will not produce fruit, as it needs a big drop in temperature between day and night and two months of temperatures under 10 degrees C (50 degrees F) to trigger flowering. The plant can be moved outside once all danger of frost has passed (i.e., after the Victoria Day weekend) – help it adjust to the outdoors gradually by keeping it in a sheltered area for several days, then putting it out where there is more sun and wind. Make sure the soil does not dry out. After about a week, you can put the tree in full sun, and it can stay outside until just before the first frost. Bring it inside gradually, i.e., move it to a partly shady spot for a week, before bringing it back inside.
If the roots look overcrowded, repot the tree. And remember to prune the growing tips if the tree is getting too spindly – this helps it remain bushy. Cut around 0.6 cm ( ¼ inch) above the spot where leaves attach to the stem.
With care, your indoor olive tree can survive for up to 9 years.