Black Olive Bonsai Care Guide
Bucida spinosa does not actually produce edible fruit like a traditional olive tree and in fact isn't even related to fruit-producing olive trees. This species is found in the upper Florida Keys as well as the Caribbean, although its native status in Florida is a matter of debate among some people. It is protected in most of its native habitats, so cannot be collected in the wild.
Dwarf Black Olives practically bonsai themselves – they have a naturally interesting appearance, making them a favorite among bonsai artists.
This semi-deciduous evergreen has a smooth, grayish-brown trunk (with age the trunk becomes more textured) and dark, leathery blue-green leaves. The spinosa has the smallest leaves of all Bucida, making it favorable for a bonsai. It stays true to its name – spinosa – with thorny spines growing along the branches.
The Black Olive's branches naturally bend at an angle of about 25-35 degrees between every internode, making it even more desirable as a bonsai. If grown outside in the ground, this species may grow to a height of 15-20 feet, though 12 feet is more typical.
Bucida sp. produces small, mild-smelling beige to yellowish flowers. The tree will drop some leaves, though not all, during the winter, and sometimes throughout other parts of the year as well. The leaves can turn to red or orange before dropping and new growth regenerates quickly, in about a week.
Black Olive is a tropical, and thus must be kept in temperatures above 40 degrees Fahrenheit at all times. It is, however, a semi-deciduous tree and should be kept below 64 degrees Fahrenheit in winter if possible.
This bonsai loves sunlight and although it can be kept indoors, outdoors is best in summer and when inside, the tree should be exposed to as much natural sunlight as possible.
Bucida is a water-loving species, so neglect of monitoring and watering could result in the tree dropping leaves. Assess the tree's water needs regularly, never allowing the soil to become completely dry. Water when the surface of the soil appears dry, and use a gentle method, avoiding soil disturbance as much as you can.
This species may need watering every day, particularly in hot, sunny climates where the tree is outdoors in long hours of full summer sun.
This particular species enjoys frequent fertilization. We recommend using a liquid bonsai fertilizer and apply each month, excluding winter. In the growing season the plant can benefit from a nitrogen boost.
Some growers prefer a time-released formula with a ratio of 18-6-8. Other time-release options for general fertilizing are Vita-Gro, and Biogold. (Biogold is the most popular among the pros.)
The Black Olive lends itself beautifully to windswept form, as that is its propensity in nature. It can, however, be coaxed into a variety of shapes with the use of bonsai wire, due to the trunk and branches being flexible when the tree is very young. Check the tree often when wired because the bark will scar if the wire is left on too long or not adjusted. You may want to use rafia for protection.
Because this variety of tree is a slow grower, be cautious with pruning branches. To develop foliage, pinch the shoots rather than cut, and never remove all new growth. Unlike other bonsai species, the Dwarf Black Olive does not grow new shoots at the site of a pruned branch. It's best to avoid creating your own jin, as the bark is fragile and may crack.
May be propagated from seeds or cuttings, although difficult. Large cuttings typically don't take, rather tip cuttings should be used, and they are slow growing.
Seeds should be collected without touching if possible, and are most likely to germinate if planted within 10 days after ripening. Plant the seeds in a well-drained soil mix of vermiculite, loam, and peat, in a community container. Germination may take up to 35 days. Transplant two-inch seedlings to single pots and cover with plastic for five days. Place the plants in shade for about four weeks. Expect roughly two inches of growth per year, although it can be accelerated slightly by gently bending the branches below the growing tip.
The Dwarf Black Olive should ideally be repotted in early summer – once every few years – so that the roots have time to regenerate before winter. This tree has a sensitive root system and no more than one third of the roots should be pruned during repotting.
Insects/Pests & Diseases:
This tropical bonsai is relatively resistant to pests and disease. It may occasionally experience ants, eryphide mites, or aphids. A gentle insecticide may be used if necessary.
Bucida sp. may also suffer from mold, particularly during the wet fall and winter months. A mild fungicide can be applied to control this problem.