Hawaii’s climate is well suited to growing many types of tropical and subtropical fruits in nearly all parts of the island. Fruit is always great and even better if it comes fresh and at its peak of ripeness from the yard. And a diet of fresh fruits is a good source of minerals, vitamins and fiber that are a part of a well-balanced diet.
Long-standing choices for backyard fruit trees are avocado, citrus (tangerine, pumelo, lemons, lime, oranges), banana, lychee, longan, mango, papaya, pineapple, breadfruit, coconut, guava, passion fruit and mountain apple. The list can also include mangosteen, figs, soursop, egg fruit and many dozens more. And we cannot forget some of the subtropical/temperate fruits such as low chill peaches, apples, pears, blueberries and plums, which are fairly common on Hawaii Island.
If yard space and waiting time are not a factor, and risk taking is in your disposition, you can plant and grow all the different fruits on your list. But for many of us, one of the hardest decisions to make is what to grow because of space limitations and environmental factors. When selecting fruit trees to plant, the first thing that comes to mind is what you want to eat and be able to share the remainder. There is no point to planting fruit trees that sound exotic, planted to impress your relatives or because it just looks good in the yard. Other important considerations are wind, rainfall and elevation. Excessive wind can batter your developing flowers and fruits, reducing the quantity and quality of harvested fruit. Rainfall amounts influence the humidity and moisture levels surrounding the plant including canopy and root zones and will influence the development of disease and insect pests. Drier does not mean better as some fruit will do better while others will not and this goes for disease and insects also. Elevation influences the temperature and the higher you go the cooler it gets, making it perfect for those subtropical and low chill varieties.
Considerations to make after you have decided on what fruit trees are suitable for your area is to locate the perfect spot in your yard. The amount of sunshine, soil availability and depth, space requirement and time to fruit tree maturity should all be considered. As mentioned before some fruit trees prefer cooler or warmer, dry over wet, well-draining soils to high moisture soils, or shallow soils to deep soils. Living in Hawaii, our soils are nearly always a product of volcanic activity, separated by the level of aging and weathering it has undergone. Here, rainfall is a major influence on how fast volcanic rock will weather and the major reason why the windward side tends to have deeper soils. In general, soil nutrient levels can be amended to the proper level and even rock can be broken down mechanically.
It is also important to know that all fruit trees have a maximum size they will attain if provided nutrients, water and room to grow. This information is well-established in the many growing guides available. If the selected site is smaller than the required space, or too close to the home, several options are available. Selecting a smaller stature variety would be a good first choice such as dwarf varieties. In their absence, pruning can also be employed to control tree size to a manageable size. A benefit to a smaller size tree is ease of harvesting, although it may produce less fruit.
Another consideration is whether the selected fruit tree has a propensity to become an invasive species. While many fruit trees we tend to plant are non invasive, you can check out the Hawaii-Pacific Weed Risk Assessment site for a list of about 1,600 plants already assessed, including fruit trees. If your plant is not on the searchable list, you can complete the questionnaire of 49 questions that ask about the plants ability to set seeds, its ability to potential disperse and naturalize into the surrounding environment, how long seeds stay viable in the environment, and how competitive it is to determine a plants tendency to be invasive with 95 percent accuracy that it would be an invasive plant.
If you need help in finding the right fruit tree or have a question about trees you already have in your yard, you can call the Hawaii Island Master Gardeners hotline at the Komohana and Kona Cooperative Extension Service offices. Trained volunteers can find answers to many of your fruit tree questions.
So who trains these volunteers? Well, it is a group effort of experts in various areas related to agriculture. The newest member to join the team is Alyssa Cho, who will be joining the University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources on July 1. She will be based in Hilo at the Komohana Research and Extension Center where she will conduct research projects in the area of sustainable fruit production for Hawaii.
For more information on this and other gardening topics, visit the UH CTAHR website at http://www.ctahr.hawaii.edu/Site/Info.aspx or any of the Cooperative Extension Service offices around the island. Nagata can be reached at russelln@hawaii.edu.