HOMEOWNER'S GUIDE- Landscaping

The way you landscape can help reduce groundwater and ocean pollution by preventing erosion and filtering out runoff pollutants. Here are some landscaping tips:

• Maximize your vegetation use- lawns, shrubs, trees and gardens all help capture runoff. Trees and shrubs require less water, fertilizer, pest control and maintenance than grass;
• Use deep-rooted plants which absorb water and nutrients better than shallow- rooted plants;
• Mulch planting beds with compost, algae, woo
  
  d chips, grass clippings and other organic material to suppress weeds, retain moisture and recycle nutrients;
• Use native plants that are adapted to local soil and water conditions. It is prohibited to take these from the wild but there are a number of nurseries you can get them from;
• Remove invasive exotic plants such as Miconia, ivy gourd, fountain grass and banana poka as they may dominate the habitat, stress out other plants and cause more erosion through their short roots;
• If your garden is sloped try and plant across it instead of up and down;
• Don’t cut the grass too short as it can stress the grass and encourage pests and weeds.
• When cutting the grass leave cuttings on the lawn so that nutrients can be recycled.

Fertilizer Use
Fertilizer in the groundwater can increase movement of nitrates and phosphates into the ocean- this directly contributes to algal blooms and coastal pollution which threatens our marine life. If you are going to use fertilizer it must be used at the right times and in the right amounts.

• Test your soil for pH, nitrogen, phosphorous and potassium to see what nutrients your plants need before applying them. You can either do it yourself or thr ough the Cooperative Extension Service 322 4892;
• Phosphorous can be applied to the root zone of your soil before planting since it doesn’t move through most soils;
• Your soil pH should be 5.8 to 7.5 pH. The correct pH allows for phosphorous, potassium and nutrients to be more available for plant uptake. If you need to increase the pH add lime or dolomite. To decrease the pH add sulphur;
• Use slow-release fertilizers to reduce nitrogen loss- this is especially important near runoff areas;
• Use organic fertilizer that is lower in nitrogen and releases nutrients slowly;
• If your soil has adequate levels of phosphorous and potassium you could use a nitrogen-only fertilizer. This may be the case for lawn and woody plants;
• Use grass with low nitrogen requirements, such as centipede grass (Eremochloa ophiuroides) or St. Augustine grass (Stenotaphrum secundatum);
• Use a calibrated spreader to apply the right amount of fertilizer evenly;
• In the winter when plants are growing more slowly you can reduce the amount of water and fertilizer;
• Don’t fertilize on windy or rainy days;
• Don’t fertilize in areas where there is high runoff, such as near storm drains or on walks and driveways;
• Water lightly after applying fertilizer;
• Compost green waste and kitchen scraps to make organic mulch for the soil. For more information about composting contact Recycle Hawaii 329 2886.

 Pesticide Use
Try to use as little pesticide as possible- this includes insecticides, herbicides, fungicides and rodenticides. Pesticides are chemicals that are designed to kill things and can be harmful to human health and the environment if used in improperly. Pesticides can leach into ground water tables and end up in our water table or the near shore ocean. It is estimated that home gardeners use more pesticides per square foot then farmers use in their fields. Here are some ways you can cut down on pesticides and still have healthy landscaping:

• Water lightly after applying fertilizer;
• Buy disease and pest-resistant plants;
• Rotate your vegetables to minimize pest populations;
• Use herbs and flowers that repel pests and attract beneficial insects (pest predators), for example crown flower, sweet alyssum, mints, basil, marigold, and chrysanthemum. Plant these as borders around your garden or between rows of vegetables;
• Introduce natural predators such as ladybugs, preying mantises, or area specific parasites that kill pests;
• Remove pests by hand- put eggs, larva
  
  e, cocoons, and adults in soapy water to kill them;
• Construct insect barriers such as screens over plants, or wrap aluminium foil around each plant base;
• Spray water from the garden hose to dislodge pests such as mites and Aphids;
• Remove insect attracting debris such as fallen fruits and vegetables, baskets, pots, old sacks, and rubbish;
• Soil rich in boron, iron, magnesium, manganese, zinc, or copper may be more resistant to pests and disease;
• If you use pesticides make sure you dispose of them properly. Call the National Pesticide Telecommunications Network at the EPA (800) 858-7378 or Hawaii 974-4142;
• If you have to throw pesticides away at a proper landfill wrap small amounts well in plastic and use kitty litter to absorb and dispose of larger quantities.

Pesticide Alternatives:

• Pesticides that use synthetic pyrethroids rather then organophosphate or carbamate bases remain in the environment for less time;
• Pyrethrum is a direct spray on pesticide that is not very toxic to mammals.
• Putting 8 drops per quart of dish soap in a bucket and wiping leaves with it can kill pests;
• Mixing 1 cup of cooking oil with 1 tablespoon of dish soap and then add 1 to 2 teaspoons of the mix to a cup of water is a great spray on alternative pesticide. This is very effective against white-flies, aphids, and spider mites;
• Insecticidal soap applied every 7 to 9 days is effective against aphids, mealybugs, whiteflies, scales, earwigs, rose slugs, crickets, spittlebugs, and others;
• Horticultural oil can been sprayed on scale insects, red spider mites, mealybugs, and
  whitefly larvae;
• Copper fungicide can be used to coat leaves which will protect them for weeks from mildew and blights.

Some common household pests can be controlled with these methods:

• Ants: Find where the ants are coming in by following the ant trail. Then pour cinnamon, red chili pepper, salt, dried mint, or old perfume and block the entrance. Use ant traps as they are localized and don’t spread chemicals;
• Mosquitoes: Remove any pools of standing water. Use citronella candles. Keep natural predators including spiders, dragonflies, and praying mantises;
• Roaches: Use technical-grade boric acid or borax in cracks and dark areas. Seal all food in jars, wash dishes immediately, pick up any leftover food bits, and don’t leave pet food out overnight. Use roach traps as they are localized and don’t spread chemicals.

Water Use
Overwatering can create runoff and leach nutrients and pollutants into the groundwater.

• Minimize use of plants that need a lot of water, or group them together in wetter areas;
• Water only when necessary and preferably when its coolest in the early morning or after sunset;
• Water longer and less often up to a depth of 4-6 inches;
• Use drip irrigation systems which can reduce the amount of water use by 50%;
• If you use sprinklers direct them away from paved surfaces as they waste water through evaporation.
  
  Photographs: Robert Shallenberger, Doug Sell and Andrew Walsh.