Learn to Water Effectively
Improper watering is one (if not THE) major reason why plants perform poorly, do not overwinter well and are constantly prone to insect infestations and disease. Learn to use proper watering techniques on all plants including perennials, annuals, vegetables and grasses (ie lawn). Water deeply and less frequently. In order to be of use to the plant the moisture must penetrate deep into the soil -- at least 6-8". Deeper is better. Water your plants and test the soil to see how deep the moisture has penetrated. You will be amazed at how much watering is necessary in order to be effective. Avoid shallow, frequent watering which creates a humid, moist atmosphere around the plant and promotes fungal diseases, rot, and attracts insects. Frequently watering also encourages the germination of weed seeds. Allow the top 1-2 inches of soil to dry out completely between waterings. By watering deeply and less frequently you will be growing plants with deeper roots which are then more able to withstand drought, winter temperatures, and also diseases and pests.Defensive Alternatives
Sometimes despite best efforts, insects or disease attack a perennial, and it may be necessary to take some type of action.
Applied very early in the season, an ammonia soak can be very effective, particularly around Hosta. Combine 1 part ammonia with 20 parts water. Soak the soil surrounding Hosta and/or other perennials. This must be applied before plants have emerged from the ground and NEVER directly onto a plant. Caterpillars, Aphids and Other Undesirable Insects
Some larger insects such as caterpillars may be also be controlled by hand picking, but usually they are too small and too numerous. A similar but more effective alternative is the shake and destroy method. Spread newspaper or scrap cloth under the plant. Then shake the plant vigorously, dislodging the bugs and hopefully dashing them to the ground. Carefully gather up the groundcover and burn, soak in water, or dispose of in a tightly sealed garbage bag.
Sometimes bugs can be blasted away with a steady stream of water. If using this method, make sure the spray is hitting the underside of the leaves. The water jet method works best if used on a regular basis -- even daily -- during periods of high infestation.
The most popular methods for controlling bugs are sprays, and there are many effective home remedies. Most are cheap, safe, and easy and convenient to use. Following are some recipes that I use on persistent bugs. If one recipe does not appear to be effective, try another or slightly change the ingredients. Basic Soap Spray
Quart hand sprayer filled with warm water
Add a squirt of non-detergent soap such as Ivory or baby shampoo Do not use detergent as this could harm your plants. Additions to the Basic Soap Spray
It is most convenient to prepare additives in larger quantities and store the mixture for future use in a glass container, such as a small jam jar. When using the mixture, just add a teaspoon to your quart container of basic soap spray. It is best to test the mixture on one or two leaves before spraying the entire plant, to ensure that no leaf damage will result.
1. Oil Additive
Add a teaspoon of vegetable oil to the basic soap spray to improve adherence.
2. Garlic Spray
Combine about 1/2 cup of mineral oil with a dozen or so crushed cloves of garlic. Allow to stand for 48 hours. Strain. Start by using roughly 1 tsp in your quart sprayer.
3. Hot Spray
In a food processor, liquify a small onion and an entire bulb of garlic. Seep this mixture in a cup of olive oil. After 48 hours, strain the olive oil and discard the pulp. Add a half teaspoon of cayenne pepper. Store in a glass jar. To use, add a teaspoon to basic soap spray. Nicotine Spray
Soak an old broken up cigar in a quart of water for 48 hours. Strain and use. If this "tobacco tea" is very dark, it can likely be diluted.
"Safe" sprays are available commercially, the most popular being insecticidal soaps. When buying these products, carefully read the ingredients on the label to ensure that no toxic ingredients have been included. Do not rely on the product name alone. A name like "Green" or "Environmentally Safe" does not mean that the product is non-toxic.
Generally, studies have shown that home remedies are as effective as commercial spray. However, home remedies may damage plants if used in high concentrations. Cautious experimentation is advisable. It is also helpful to keep some notes documenting mixtures and their effectiveness for future reference, and to share with fellow gardeners. (Just like cooks share recipes.) Plant Diseases
Well-maintained, vigorous, perennials are generally disease free. However, certain popular varieties are prone to persistent fungal conditions such as powdery mildew, rust, and botrytis.
Mildew is a white, powdery fungus that covers the leaves and stems of infected plants. Although rarely fatal, it does rob the plant of its beauty. Plants most routinely affected are Summer Phlox, Monarda, and Asters.
Rust is another type of fungal infliction that disfigures the plant's beauty but rarely kills. Members of the Mallow Family, in particular, Hollyhocks, seem most prone to this disease. Rust usually attacks the leaves, causing conspicuous red-orange blemishes.
Botrytis is a very serious fungus disease which may destroy the entire plant if not treated early. It is most frequently seen in Peony and is characterized by brownish-gray mould on the foliage, which subsequently wilts and turns black. At the first sign of this disease, remove infected parts and burn them.
Many fungal diseases can be discouraged by good garden sanitation. It also helps to locate susceptible plants in moist, fertile soil, in a spot with good air circulation. Water-stressed, or crowded, plants are more prone to fungus infections. Excessive moisture on the plant's foliage is also a factor that contributes to the spread of fungal spores. Watering the plant is therefore best done at ground level, rather than spraying water over the plant.
There are several home remedies available that will control and act as a preventative for many fungal diseases: Baking Soda Spray
1 quart of water
1 teaspoon of baking soda
1 squirt of liquid, non-detergent soap
Spray infected leaves thoroughly, including undersides and stems. In damp weather repeat regularly. This is an effective mixture to help prevent botrytis, black spot, rust, and powdery mildew. Potato Starch Spray
1 quart of water
2 to 4 tablespoons of potato flour
1 squirt of liquid, non-detergent soap
In addition to fungal diseases, this blend is also an effective insect spray. Sulfur
Sulfur has been used as a natural fungicide for thousands of years. It can be purchased as a liquid or a powder. Sulfur acts as a preventative, and should therefore be applied before the disease is evident. It is useless to spray after the blight is already visible. Bordeaux Mix
Bordeaux mix is a very powerful, organic fungicide that has been in use for centuries. It is available commercially as a powder which can be dusted onto plants, or mixed with water and sprayed. Read the directions very carefully, and if in doubt, use a solution that has been severely diluted. In excessively high concentrations, Bordeaux Mix can kill the plant.