By LINDA BRANDT, Correspondent
The idea of making your own garden supplies is seductive. And so some gardeners look to their kitchen to concoct their own pesticides, fertilizers, weed killers and soil amendments from familiar and harmless ingredients that may cost a fraction of what they find in the store. How harmful could vinegar, dishwashing soap, vegetable oil, garlic, onion and baking soda be? It turns out, as with any garden powder, spray, soak or amendment, some caution is required. Children and pets should not be directly exposed to any of these solutions, and people with allergies or breathing problems need to take the precautions they would with any product. Also, homemade doesn’t mean organic — that depends on the ingredients you use.
Soil type, rainfall, sun exposure, plant type, insect identification, time of year and time of day play a role in what works. A mixture that will kill harmful insects can also kill beneficial ones. Ditto for weed killers, and just like any fertilizer, over-application can lead to problems. Because of the ingredients in them, most sprays should be applied in early morning or evening.
Plants should be sufficiently watered before fertilizers or insecticides are applied and diluting them to a safe concentration is important. If you are using a fertilizer or insecticide for the first time, test it on a few leaves to be sure it will not damage the plant. Do not apply to tender new growth on plants or to fruit trees in bloom.
Each ingredient has a function.
Soap helps sprays stick to leaf surfaces. It smothers insects and penetrates their protective coverings, but it can do the same thing to the protective waxy coating on leaves.
To minimize damage to plants, rinse plant with water two or three hours after application of insecticides. Most of the formulas below call for mild dishwashing or liquid castile soap (based on vegetable oil rather than animal fats) or baby shampoo.
Avoid detergents that contain a degreaser. Antibacterial soaps may discourage the development of beneficial bacteria.
FIRST, A WORD OF CAUTION
Entomologists at the University of Florida recognize that home gardeners have an interest in making their own insecticides. The calcium, magnesium and iron found in hard water can render insecticidal soap useless.
Dr. Don Short suggests making a test jar of water and the kind of soap you will be using. Wait 15 minutes. If the mixture is uniform and milky, your water is fine. If a film develops on the surface of the water, he suggests using a product such as Calgon to soften it.
Oil smothers insects and also helps foliar fertilizers and insecticides stick to leaves. Try to treat only the affected plants and only the offending insects. However, for a severe infestation, spray the plant from the top down and from the bottom up, coating all upper and lower leaf surfaces.
Formulas containing hot pepper powder or sauce can irritate eyes, noses and mouths of pets and wildlife, which have no way of washing it off. Eye infections may result from excessive scratching after exposure.
Because you probably already have on hand the ingredients for these formulas, they will cost you little or nothing. They have been used successfully by other gardeners and are certainly worth a try. And if they are successful, you can use the money you save to buy a new pruner or rake, decorative pot, statuary or decorative stone for your garden.
INSECTICIDES
Before making an insecticide, you will want to know what kind of infestation you have.
One way to get rid of insects, especially at the first signs of infestation, is a strong stream of water. Homemade insecticides are only effective if they come in direct contact with the insect.
All-purpose insect spray: Chop, grind, or liquefy 1 whole garlic bulb and 1 small onion. Add 1 teaspoon powdered cayenne pepper; mix with 1 quart of water. Steep 1 hour, strain and add 1 tablespoon liquid dish soap. Mix well. Store refrigerated for up to 1 week.
Basic insecticidal soap spray for aphids, earworms, borers, mites, whiteflies, maggots and moths: With 1 quart water, combine 1.5 teaspoons liquid soap, castile soap or Ivory. To use on scale, add a quarter cup isopropyl alcohol.
Spider mite spray: Combine 1/8 cup buttermilk, 1 cup whole wheat flour and 1 gallon plus 1 quart water.
For soft-bodied mites, aphids, mealy bugs: Combine 1 tablespoon canola oil and a few drops of Ivory soap in 1 quart water.
Garlic oil spray for whiteflies, aphids, beetles: Combine 3 to 4 cloves minced garlic with 2 teaspoons mineral oil. Let sit overnight; strain out garlic and add to 1 pint water and 1 teaspoon biodegradable dish soap. To spray, use 2 tablespoons spray in 1 pint water.
Hot pepper spray for mites: Mix 2 tablespoons hot pepper sauce or cayenne pepper, a few drops of biodegradable dish soap and 1 quart water. Allow to sit overnight.
Simplest soap spray for aphids, scale, mites and thrips: Add 1 tablespoon dishwashing soap to 1 gallon water.
To get rid of slugs: Wait until dark when they come out to feed and then spray them with diluted ammonia or sprinkle them with salt. You can also trap them under overturned flower pots with a stone placed under the rim to allow slugs to crawl into the dark, damp space. Use grapefruit halves in the same way. Or set a wide board on the ground near where they feed. They will hide under the board to avoid the sun.
Fungal diseases: Combine 2 tablespoons baking soda and 1 quart water. Spray affected area every few days until problem has cleared up. Cinnamon is a natural fungicide: wet affected leaves and sprinkle cinnamon on the fungus.
Powdery mildew: Combine equal parts milk and water. Spray on infected plants 3 times a week. Or combine 1 tablespoon baking soda, 1 tablespoon vegetable oil and 1 tablespoon dish soap in a gallon of water. Spray on plants to prevent fungal spores from germinating.
FERTILIZERS AND SOIL AMENDMENTS
Banana peels: Throw 1 or 2 banana peels in the hole before planting to provide a shot of potassium to new plants. Or bury peels under mulch to compost naturally for established plants.
Coffee grounds: Acid loving plants such as tomatoes, roses and azaleas will benefit from coffee grounds mixed into the soil or sprinkled on top of the ground before watering. Or soak 6 cups coffee grounds in a 5-gallon bucket of water.
Let it sit for 2 to 3 days and then saturate the soil around your plants.
Egg shells: Crush and then work the pieces into the soil near tomatoes and peppers. Also work them into homemade potting mix. Egg shells are high in calcium carbonate, the same ingredient as lime.
Seaweed fertilizer spray: Make a concentrate of 1 ounce dried seaweed (available in Asian markets) mixed with 1 gallon warm water. Shake well. To use, add 3 tablespoons concentrate to 1 gallon water. Use as a foliar spray or root soak.
Sugars: Molasses, dry molasses powder, brown sugar and corn syrup feed aerobic bacteria in soil and in compost tea. Sugars should be dissolved in compost tea that has brewed at least 1 to 3 days. Adding too much at one time may cause a temporary nitrogen deficiency. Unsulfured molasses acts as a mild natural fungicide.
Molasses fertilizer: With 1 gallon of water, combine 1 cup compost tea, 1 ounce molasses, 1 ounce cider vinegar and 1 ounce liquid seaweed fertilizer (see above). Let cure for 24 hours before spraying on plants.
NOT FROM THE KITCHEN, BUT FREE AND EASY
Sun brewing: Add a big handful of weeds to 2 or 3 cups water in a glass jar and set out in the sun for 1 to 2 days. Strain. Stovetop: bring weeds and water to a quick boil. Remove from heat and cover. Allow to soak for a few hours; strain. Dilute 1 part weed tea with 4 parts water for a root soak fertilizer. To use as a foliar spray, add a quarter teaspoon liquid soap.
Grass clippings: Make a nitrogen-rich fertilizer by filling a 5-gallon bucket of grass clippings and filling with water. Let sit, covered, for 3 weeks, stirring once a week. Make a concentrate by mixing 1 cup of this concentrate with 10 cups of water. Dilute at a rate of 1 part concentrate to 4 parts water before applying to plants.
Weed killers: Household vinegar sprayed full strength or diluted will kill many common weeds, especially immature weeds. Boiling water will kill weeds as well. Use a funnel to be sure it only goes on weeds and not surrounding plants. Or mix 1 tablespoon rubbing alcohol with 1 quart of water. Spray on weeds.
For tougher weeds, increase the concentration of alcohol.
