Tropical Gardening: Hamakua Harvest festival focuses on healthy farming for healthy communities

If you enjoy farming and gardening, don’t miss Hamakua Harvest’s second annual Farm Festival from 8 a.m.-3 p.m. May 21 in Honokaa.

It’s a great opportunity to support island farmers and learn some valuable farm and garden techniques. There will be vendors of fresh produce, nursery plants and crafts. There also will be educational presentations on everything from composting and mulching to grafting fruit trees by Ty McDonald with the University of Hawaii College of Tropical Agriculture and Human Resources.

The day will be vibrating with music, entertainment and Hawaiian cultural activities. The ever-popular Dominic Yagong will emcee for the day, featuring island dance and musical artists. The day also kicks off Honokaa Western Week.

For more information, contact Lori Beach at info@hamakuaharvest.org.

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Now, let’s explore ways you can make your gardening experience more enjoyable, environmentally sound and sustainable.

For example, when weather conditions are dry, it is a good time to consider ways to conserve water. Organic material is essential to good soil. Decomposed organic matter helps increase water- and nutrient-holding capacity of the soil. Unrotted material such as leaves and clippings used as surface mulch can help conserve moisture and keep weeds under control.

Nematodes, those little microscopic worms that feed on roots, will do less damage in a high organic soil. Organic matter also can increase the minor element and microbiological activity of your soil.

For those reasons, it is vital to save your grass clippings and leaves. They are like money in the bank. You can store these materials in a corner of the garden.

Decay of plant material deposited in a compost pile can be hastened through the use of fertilizer and manures.

For each bushel of leaves or grass clippings, add 2 cups of balanced fertilizer (composed of nitrogen, phosphorus and potassium) and 1 cup crushed coral, dolomite or hydrated lime.

Build the compost pile in layer cake method, with a layer of plant material 6 inches deep. Continue until the pile is 4 feet high or so.

After the pile shows signs that decay is well underway, usually four to five weeks, mix the pile by turning it over. A pitchfork would come in handy at this point. The compost is ready to use in about three months. It is an excellent material to mix with soil for vegetable gardens and new plantings.

Anthuriums especially thrive on compost. They love that high organic, well-aerated mix with good water retention capability, yet good drainage. A good mix needs to be able to anchor roots and the stem so the plant will not topple over as it grows upward yet provide sufficient moisture, nutrients and aeration to the plant. Cinder or crushed rock added to composted wood shavings, macadamia nut shells or peat or tree bark will serve to better anchor roots.

Even with composting and mulching, you will still need to fertilize your garden.

Some Hawaiian soils are very young and low in nutrients. Larger amounts of fertilizer are needed for fast-growing plants and lawn grasses than where soils are older and better developed.

The soil is not only lacking in primary elements, such as nitrogen, phosphorus and potassium, but it is deficient in secondary elements such as calcium and magnesium. Then there are those “minor elements” such as manganese, iron, copper, zinc and boron. Even if all elements required are there, they might not be available because of high alkalinity or very acid soils.

When plants are grown in these mineral deficient soils and fertilized with ordinary plant foods, they often develop various deficiencies.

Several years ago, plant doctors studied these deficiencies and learned not only how to recognize the affected plants but also that they could be corrected by applying the minerals in which the plant was deficient.

But what average gardener has the training that enables him to recognize deficiency symptoms in plants?

To overcome this problem, the “nutritional spray” was developed. It is a mixture that contains about all of the minerals in which a plant can be deficient. This is especially effective with alkalines that are not easily neutralized.

At first it was necessary to add lime in order to neutralize these solutions, but now garden stores have mixes that require no lime.

Some plants are more subject to mineral deficiencies than others. Especially vulnerable to mineral deficiencies such as dieback, mottled-leaf, small-leaf and yellow-leaf are hibiscus, gardenia, mock orange, ixora, mango, avocado, macadamia, coffee and citrus.

Two to three times a year is usually enough to apply a nutritional spray.

Commercial growers apply the nutritional spray as a preventive measure. It is easier to prevent deficiencies than correct them.

In new gardens, it might be necessary to apply a nutritional spray about every three months for the first year in order to keep ahead of deficiencies.

Along with the nutritional spray, it is a good idea to use a soil application of the minor elements. Magnesium, iron and zinc are the most important elements, but occasionally we find plants with boron, manganese, copper and other trace element deficiencies. There are several “shotgun” combinations available at your supply store.

Certain plants require larger amounts of various elements than other plants. As you get acquainted with our tropicals, you will find for example that iron is especially important for ixoras, hibiscus, azaleas and gardenias or that magnesium keeps leaves of coconut and areca palms from getting orange-colored and dying prematurely. Zinc is the vital element in growing queen palms, royal palms and palms in the date group. Howea, or kentia palms, and our native Pritchardia, or loulu, palms suffer from twisting distorted growth patterns because of boron deficiency.

Increasing your soil organic matter and using a shotgun treatment of trace elements as a spray or soil application or both will keep your plants from having these deficiencies under most conditions. Remember to follow directions on the label. Too much of the important plant nutrient materials can be as bad as than too little.

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Another fun event to catch on the 21st if you can is the Vireya Rhododendron Society meeting at Keaau Community Center. It is a potluck at noon, with the program presented by Stephanie Williams on tropical rhododendron propagation made easy. For more information, call Sherla Bertelmann at 966-9225

If in doubt about your soil type and pH, you can have your soil tested. This information is supplied by the University of Hawaii College of Tropical Agriculture and Human Resources. For more information about soils and testing, contact the office near you.