One of the advantages of living in Hawaii is that we can garden all year, and winter is actually the best season for planting a number of vegetables. It is also a time when gardeners can perform tasks that will help plants do well all year.
Among them is pruning ornamental shrubs and trees. It’s easy to follow the architecture of a tree to encourage outward-facing growth and eliminate crossing branches. Discard dead, broken or diseased branches when they occur. As a rule, do not remove more that 25 percent of the tree canopy at once.
However, deciduous trees such as monkeypod, which lose their leaves seasonally, can be pruned extensively during the dormant season.
Plumeria benefits from pruning after the leaves have dropped, but it’s best to prune judiciously to enjoy blooms through spring.
If your plumeria has struggled with rust, whitefly or other pests, clear debris to prevent further infestation.
Pikake is usually pruned from November to January. Hybrid tea roses grown at elevations of more than 3,000 feet may be pruned during semidormancy in the winter.
Insect pests slow down during winter, but keep an eye out for downy mildew on crucifers, roses and basil. The disease can be especially prevalent in areas with high humidity and rain when mornings are cool.
Basil downy mildew was discovered in Hawaii in 2011, and in a few years it has done much damage.
To check for downy mildew, look for yellowing with some brown spotting on the upper surface of leaves and fuzzy, grayish-brown growth on the underside of leaves. If your plants are affected, dispose of infected plant parts and be sure to sanitize hands and tools afterward.
For more on downy mildew, visit ctahr.hawaii.edu/site/downloads/bdm/ factsheet.pdf. The information is published by the College of Tropical Agriculture and Human Resources, or CTAHR.
In lower-elevation gardens of less than 1,000 feet, almost anything can be planted during winter. In particular, lettuce, cabbage, beans, bell peppers and mustard thrive when temperatures hit 65 to 75 degrees.
The same goes for medium elevations of 1,000 to 2,000 feet, though eggplant, iceberg lettuce and okra are not recommended. At higher elevations, between 2,000 to 3,500 feet, avoid planting peas, various types of beans, corn, potatoes and tomatoes. In the case of potatoes and tomatoes, leaf diseases can seriously damage crops.
For further details on what to plant when, contact the master gardener program in your area.
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Lorraine Brooks is an urban horticulture extension agent and the Maui master gardener coordinator with the University of Hawaii’s Cooperative Extension Service, part of CTAHR. Email Brooks at llb@hawaii. edu. To find your community’s master gardener program, visit ctahr.hawaii.edu/UHMG.
