Wet weather presents gardening challenges
Summer is usually rainy season here in West Hawaii. This spring has been a very wet prelude to our summer. Even Alii Drive is experiencing storms dropping measurable inches of rain in a single day. Start planning your garden now for what is likely to be a wet summer.
If you’d like to grow vegetables for cool summer salads or to put on the grill, plan carefully. Most vegetables take about three months to start producing. If you plant now, you’ll likely be harvesting in August. By then the rains may have slowed a bit, but the plants will be growing during wet weather.
Many vegetables prefer drier conditions. Tomatoes, for instance, don’t mind some rain as they start to grow, but once they start flowering and fruiting dry weather is essential to prevent disease from ruining your crop. Kombucha squash vines also grow better in drier winter weather. Planting in August should produce nice winter squashes. Earlier planting risks rotting fruit.
Years of experience show that lettuce is not a good crop to grow in our soggy summers. The lower leaves rot easily in muddy soil. If you want to grow greens, try chard, mizuna or mustard. Hearty greens are best for Kona summer production. Okinawan spinach tolerates dry and wet weather fairly well. If it gets really wet, it may develop a disease that causes black spotting on the leaves. This can be remedied by removing diseased leaves and thinning the plant for better air circulation. Once the weather dries a bit, the disease will die. Most brassicas, including broccoli, collards, and kale, are good choices for spring planting. Even cabbage and cauliflower can produce well in damp weather.
You’ll have a better harvest with peas and beans if you select varieties that adapt well to wet weather. Choose ones that have edible pods. Snow peas and snap beans are good candidates. Lima beans and others that dry on the plant will do better if you plant them in the fall.
Root vegetables seem to do well year-round and you can get some nice results even in rainy weather as long as you have soil that drains well.
If you plant them in the sun, you can get corn, peppers and eggplants to thrive even if we get a lot of rain. These plants will produce better tasting fruit, even in the rain, if subjected to hot, sunny growing conditions.
It might be time to try some edibles that take several seasons to produce. Asparagus planted now should give you some nice spears by next spring. The plants will get off to a good start with our summer rains. Pineapple tops planted now should give you some fruit next summer.
Some herbs do better than others in the rain. Tender new basil plants tend to get diseased in rainy weather. Low growing thyme can drown, lemongrass rust spreads rapidly when it’s wet. Try getting shrubbing herbs going in drier weather and by next summer they’ll have woody stems to better handle summer moisture.
Avoid spring planting of low-growing vegetables and fruit. Strawberries often produce fruit that sits on the ground. The increased insect population we experience in summer will get most of your fruit if rotting diseases don’t. Select other plants for the rainy season.
Though raised beds or large containers can keep plants drier, if they are outside and get similar rains, they may not do much better than they would in your garden. Mounding your planting beds can also help the soil drain, but when it rains hard for hours, as it has been doing lately, variety selection is going to be the best solution.
Now is a great time to plant trees and fruiting and flowering shrubs. Acquiring plants to install that have been growing for at least a season means they will be higher and drier during the summer rains. Citrus, avocado or macadamia nut as well as shrubs such as blueberry or raspberry will grow quickly in the rainy season. Try something exotic like acerola, mulberry, loquat or a tropical cherry — Surinam or Brazilian.
Tropical gardening helpline
Bonnie asks: I recently spotted an interesting red broom-like growth on the branch of a large ohia tree a little way down Middle Keei Road. Do you know what it might be?
Answer: Yes, it is an aerial root. Ohia lehua trees often produce these red broom-like structures from their branches to capture additional moisture.
Many other plants do this as well, but the ohia lehua is one of the most dramatic because the roots are bright red and large, often growing over 6 feet long. Though these aerial roots do not usually touch the ground they are tightly matted and able to collect lots of additional water from the air for the host tree.
They seem to appear unpredictably and are quite stunning to see. Once they appear, they stay in place for the life of the tree. Several folks have asked about this particular specimen. If you are curious, go take a look at this one which is in the middle of a field on the mauka side of the road. Another interesting aerial root specimen has been growing on an ohia near the entrance of Hawaii Volcanoes National Park for many years.
Email plant questions to firstname.lastname@example.org for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.
Diana Duff is a plant adviser, educator and consultant living on an organic farm in Captain Cook.