The Wonderful World of Olive Trees as Bonsai
by Jerry Carpenter

Living in San Jose, South Bay, has presented me with some issues raising bonsai. Not only do I live in San Jose city area but I also have an apartment with a balcony. Water conditioning and lighting can be a challenge to manage. In the Spring most of the light is filtered well but in the summer the sun blasts the balcony and finding the right niche to shelter trees that cannot be in direct sun is always a constant worry. I have found ways to rig shade for the maples and other deciduous trees using corners and standing shade walls. Water is a serious problem and not one so easily resolved as shade. Water here in the apartment is heavy laden with salts.

In my early days of watering trees I used to top water almost everything with tap water. I began to quickly notice white salts on leaves and worse, white salts standing on the soil and at the root base of my trees. Some trees died within a few years and the rest need repotted often to clean the salts. Olive seem to thrive though. Now I use filters to fill most every watering can I use. It is time consuming but has helped some.

The reason I speak of shade and water is because the Olive grows well here and is very tolerant of the water condition. They are tolerant to salts, can take the heavy blasts of sun and grow like crazy year after year.

Most olives have deep green leaves with greyish undersides, and produces yellowish-white flowers followed by green or black fruit in late summer or early fall. Getting one to actually flower and fruit has been an effort of mine. I have not had much success at that yet most like due to sun conditions and temperatures in the spring.

The olive is a robust tree - it is tolerant of wind (both hot and cold), soil condition and elevation and can live 800 to 1000 years in the ground. It is much loved by bonsai enthusiasts as much for its rich historical and mythical lore as it is for its elegant shiny green leaves and trunk which takes on an aged, stony appearance after as little as five years of growth.

Olives have their own family: the Oleaceae family. They take a full sun in summer, less require much less light in winter. For this particular reason they will tolerate display and living condition indoors in the winter requiring 1000 Lux as an indoor plant.

Growing in the Bay area can present some challenges as far as consistent temperatures for constant development. Leaves can withstand temperatures down to 43F. The can just stop growing when night time temperatures drop to low. They will sit and look dormant. The roots dislike freezing temperatures. The olive can be successfully grown as an indoor plant, but it is best to keep it outdoors in the summer, and should be kept below 64F in winter to allow a dormant phase. To encourage fruiting, the plant should be kept for several weeks with nightly temperatures of 35F and daily temperatures of 60F.

You must water an olive thoroughly, but keep slightly dry. Reduce watering in winter. The olive may benefit from daily misting. I give mine water every other day, except for the hottest days, and mist regularly.

You should feed every two weeks from spring to autumn. Do not fertilize for three months after repotting. Use liquid bonsai fertilizer such as seaweed, or granular 5-5-5 for topsoil feeding. I use VF-11 almost every other watering, HB101 to condition water after hot days, and some organic water soluble feeding once a month in the summer months.

Now for the good part. Wiring is used sparingly on olives due to their ability to scare quickly and very easily. Use wrapped wire, wire with plastic tubing for anchors, and even bamboo sticks to help space braches. Wire as little as possible.

Using bamboo sticks cut to length with wire running through or over and anchoring them to braches will help you gain space between limbs or help position them. Here is an example of some work done by Kathy Shaner on my olive to spread a multi-trunk group apart. This has aided in getting less straight groups of trunks on the group.

You can style in various except broom. Creating your own jin/shari is not a good idea as the bark cracks easily, leaving the tree exposed to fungal infestation. Do your most severe trimming and pruning before repotting or in the fall. Repot the olive when the air temperatures are consistently above 45 degrees. This puts repotting in May and June at the latest. Olives seem to perform better having their roots worked only when the soil can be warm. If you are doing a drastic root pruning, complete defoliation is advised or be prepared to lose lots of leaves. I like to prune first to reduce the canopy before doing major root work on older olives. Repot in free-draining typical soil.

Olives have some famous pests such as aphids, ants, black mold, scale. If you get a bad infestation of scale like I sometimes seem to; use a alcohol soaked cotton swab and rub gently over infected areas to kill the eggs.

Keep in mind that trees like olive are notorious back budders, which is both good and bad. It is good from the standpoint that you will have a lot of growth to work with, but it is bad from the standpoint that you will need to frequently rub off new buds that develop in the wrong places; like within existing branch forks or at the base of branches and along the lower portion of the trunk.