KONA — Tomatoes can be difficult to grow in Kona, especially at upper elevations. Our local weather patterns coupled with the many introduced insects and diseases that tomatoes host compound the challenge.
Many gardeners grow the more resistant cherry tomatoes as an alternative but another alternative exists. The tree tomato, with the new common name tamarillo, is a subtropical plant that grows well here and produces tasty fruit that resemble tomatoes and can be eaten and prepared in similar ways.
Tamarillo plants are an attractive, fast growing, semi-woody, small tree that can grow to 15 feet in ideal conditions, but will tolerate pruning to maintain it as a low shrub. The tree usually grows as a single upright trunk with lateral branches. The leaves are large, dark green ovals with pointed tips, making it an attractive plant to add to a small garden.
The tree tomato was originally known botanically as Cyphomandra betacea but has recently been reclassified as a member of the Solanaceae family with the current botanical name Solanum betaceum. This brings tree tomato relatively closer to tomatoes and others in the family including peppers and eggplants.
Native to many South American countries, the tree tomato is grown in gardens and small orchards throughout subtropical regions. Today it is cultivated in parts of Africa, India, China, Australia, New Zealand and the United States in backyards as well as commercial operations.
The popularity of the tree tomato in New Zealand led their national Tree Tomato Promotions Council to officially change the name to tamarillo in 1967. They wanted to distinguish it from the common tomato and add to its exotic appeal. Within 20 years the appeal made it popular enough for Australian grown tamarillos to become an internationally marketed crop. Commercial tamarillo orchards can now be found around the world.
This fast growing tree will likely begin flowering and bearing fruit within 18 to 24 months. Tamarillo’s fragrant rosy white blossoms hang in clusters from the lateral branches usually from May through October but often year round. Their color and fragrance attracts pollinators allowing as many as six fruit to appear out of each cluster. The egg-shaped fruit is green at first, ripening to yellow, orange, red or almost purple over a ripening period of six months or more. The ripening process varies within the clusters meaning that harvesting is staggered.
The red tamarillo is a slightly acidic while the yellow and orange varieties are sweeter. The fruit is best eaten fully ripe as it can be tough, bitter and slightly toxic when consumed unripe. The firm flesh is tasty, somewhat reminiscent of tomatoes in flavor and can be substituted for tomatoes in many recipes including salads and juices.
Tamarillos can be propagated from seeds as well as cuttings. The small black seeds are covered in a gelatinous protective layer that should be removed by washing, rubbing or fermentation to prepare them for rapid germination. Planted in a good seeding or potting mix, the seedlings will first develop an upright trunk of 3 feet or more before branching out.
To grow plants from cuttings, cut a disease free aerial shoot of 4 to 6 inches, dip it in a rooting hormone liquid or powder, place it in a mix of vermiculite and perlite or a medium that will retain some moisture while draining well. These plants will branch out earlier and lower than seedlings and can be out planted once they are at least 18 inches tall. Their growth habit will be more shrub like.
Plant tamarillos in a location that gets partial sun at lower elevations and full sun in cooler areas. They will grow best in a wind protected spot with light, fertile soil that drains well. Though somewhat salt tolerant, tamarillos shallow roots mean they can be easily uprooted in strong winds.
Tamarillos require very little maintenance. You can prune them to control size and shape or to remove branches that have previously fruited. If left in place they will produce inferior fruit the next time on the same branch. Mulching is advised to help maintain moisture in the shallow root zone and can help suppress competitive weedy growth. Regular fertilization with a balanced fertilizer will help keep the trees healthy and vigorous, producing numerous large fruit.
The tamarillo tree is generally resistant to pests. If scale, aphids, white flies or other destructive pests arrive, treat them as soon as you see them. A low-tox soap and oil mix should be all that is needed to control or arrest them.
In addition to providing an attractive plant with lovely flowers and colorful fruit, tamarillos are tasty. You can eat the fruit by scooping the flesh out of the skin or by slicing them and putting them in salads or sandwiches. They are also good fruit for making jams, jellies and sauces.
If you know someone growing tamarillo or you see them at a market, save the seeds to plant your tree. Seeds and an eBook on tamarillo are available online.
However you acquire a tamarillo plant, you will certainly enjoy its addition to your garden. Since tamarillos have a short life of about fifteen years, plan to add a new tree every five years for maximum production. Plant now to enjoy this somewhat exotic fruit and its many uses soon.
Diana Duff is a plant adviser, educator and consultant living part time in Kailua-Kona.