Growing Guide Olive Tree
Olive trees (Olea europea) are slow-growing and keep their leathery, gray-green leaves year-round. The plant is tied to a support, so please check the ties from time to time and loosen or remove them if they become too tight and cut into the stems.
GROWING IN A CONTAINER: In areas colder than Zone 8 (10°ree;F), Olive trees must be grown indoors during the winter. Choose a place for your Olive tree that receives full sun (at least 6 hours of direct sun each day). A location near a sunny, south-facing window is ideal. Take care to position your plant away from heat vents and radiators and not too close to a window, which can act as a magnifying glass and literally “fry” the leaves.
When the potting mix feels dry 1 inch below the surface, water thoroughly. Your tree will require less water in fall and winter, the seasons when Olive trees naturally take a rest, but don’t let the soil mix dry out completely.
During fall and winter, fertilize once a month with a balanced houseplant fertilizer (such as 20-20-20). In spring and summer when your tree is in active growth, fertilize every two weeks or apply a timed-release fertilizer.
If you would like to move your tree outdoors for the summer, wait until the danger of frost has passed in spring, then gradually acclimate your plant to conditions outside over a week’s time. Set the pot outdoors in a sheltered, lightly shaded spot, increasing the exposure to sun and wind each day. Check the moisture of the potting mix and water thoroughly if it’s dry. Once acclimated, keep your Olive in full sun for the summer, and bring it back inside before frost in fall.
After a year or more, when the roots of your Olive have become crowded, transplant it into a larger pot. Choose a pot that is 1–2 inches wider in diameter, with a drainage hole in the bottom. Use a fast-draining potting mix, and begin by filling the container about half-full of moistened mix. Remove the plant from the pot by grasping the rim, turning the pot upside down, and tapping it against the heel of your hand. Gently break up the sides of the root ball with your thumbs and tease apart any roots that are circling at the bottom. Then set the root ball on top of the mix and adjust the amount of mix in the container so that the top of the root ball will be about 1 inch below the rim. Fill in around the root ball with potting mix to bring the level to about 1 inch below the rim, and firm lightly. Finally, water thoroughly.
GROWING IN THE GROUND: Gardeners in Zones 8 (10°ree;F) and warmer can grow Olive trees outdoors. Before planting, give your plant a gradual introduction to direct sun and stiff breezes. Set the pot in a sheltered, lightly shaded spot, increasing the exposure to sun and wind each day. Check the potting mix and water thoroughly if it’s dry 1 inch below the surface. At the end of a week, your plant will be ready to go into the ground.
Choose a spot for your Olive that receives full sun (at least 6 hours of direct sun each day) and is protected from drying winds. The soil should be fertile but very well drained. Amend the soil, if necessary, by digging in organic matter (such as well-rotted compost) and grit or pea gravel (which improves drainage). Dig a hole about twice the width of the pot but no deeper than the height of the pot. Remove the plant from the pot by grasping the rim, turning the pot upside down, and tapping it against the heel of your hand. Gently break up the sides of the root ball with your thumbs and tease apart any roots that are circling at the bottom. Set the root ball in the center of the planting hole. Push soil back into the hole and just over the top of the root ball, and firm the soil by pressing down with both hands. Then make a rim of soil around the edge of the planting hole to form a basin, which will hold water and channel it down to the roots. Finally, fill the basin with water.
In spring, about the time small white flowers appear on your Olive, begin fertilizing monthly with a balanced, granular fertilizer (formula 10-10-10). As an alternative, use a timed-release fertilizer that lasts for up to 3 months. Do not fertilize after October.
PRUNING: After bloom in spring, clip the tips of the branches to encourage a full, bushy head on your topiary. Make the cuts about G inch above the point where a pair of leaves attaches to the stem. How much you cut off depends upon your preference for the overall shape of your topiary, but we recommend that each branch measure at least 6 inches long.
PESTS: Olive trees sometimes fall prey to soft-bodied scale, small yellow-brown insects that fix themselves to the stems and suck sap from the plant. On container-grown plants, spray the entire plant with insecticidal soap, BioNeem, or a superior oil (available at garden centers) labeled for indoor use, following the directions carefully. Dabbing the scale with a cotton swab soaked in rubbing alcohol is another remedy, but the process is time consuming and usually doesn’t entirely eliminate the scale.