Starting
off Right
Selection.
When choosing roses, select varieties that are adapted to
your growing region. If specific diseases such as black spot are known
to be a problem in your region, choose disease-resistant varieties.
Location.
Roses require a location that's sunny at least six hours a day.
Ideally, the location should provide good air circulation and receive
morning sun to help dry off leaves early in the day, which will help
minimize disease problems.
Soil
preparation. Once you have outlined
the shape of the rose bed, it's time to improve the soil--before planting
the roses. Because roses are rather finicky about soil, it's a good
idea to have your soil tested. Most university extension services will
do this for a nominal charge. Once the soil analysis is complete, you
will know exactly what should be added to the soil and in what amount.
This is not the time for skimping. Any extra effort you put into advance
preparation will pay off in superior results for years to come.
Care.
Standard care includes watering, fertilizing, and pruning. Roses
need regular applications of water for top production of flowers. It
makes no difference whether the water comes from a hose or from rain.
Just make sure the roses receive enough water to moisten the soil to
a depth of 18 inches every week during the growing season. The easiest
way to check this is with a long screwdriver or stiff piece of wire,
such as a straightened-out coat hanger. Either device will be easy to
push through moist soil, more difficult once it hits dry soil. In arid
summer climates, consider watering your roses with a drip system that
is connected to a timer.
At least two applications
of fertilizer should be made, once when new growth first starts in the
spring and again in midseason. Favor non-burning, natural formulations
that feed the soil as well as the plant.
Managing
Pests
Vigorously growing roses will be far less susceptible to attack from
pests and diseases than those that are struggling. However, roses are
susceptible to attack from a variety of pests, so it's helpful to have
some controls at the ready should you find your roses affected.
Disease
Sprays
1. Anti-transpirants, which are normally used to protect
plants from drying out, are believed to work as fungus controllers by
coating the leaves with waxes, plastic polymers, or silicones, thus
preventing fungal spores from entering the pores in the leaves. Apply
just as you would an anti-transpirant; follow label directions.
2. A mixture of baking soda and horticultural oil is an
effective method of controlling powdery mildew. This fungicide also
reduces or eliminates black spot to acceptable levels on resistant rose
varieties. Use one rounded tablespoon (approximately four teaspoons)
of baking soda (sodium bicarbonate) mixed with one tablespoon of horticultural
oil per gallon of water, sprayed on a weekly basis or after a heavy
rain. Note that baking soda can burn leaves: Apply in early morning
and not at all during hottest weather.
3.
Sulfur-based fungicides have long been the organic gardener's
weapon of choice for battling fungal diseases. However, they can leave
residues on the leaves and petals and cannot be used when temperatures
exceed 90F.
4. Whole neem oil is a promising new product for controling
black spot, powdery mildew, and rust as well as many insects and mites.
(Neem oil comes from the tropical neem tree, Azadirachta indica.)
Insect
Pest Sprays
5. Water. Nothing
fancy here, just plain old water. Keeping plants clean helps prevent
problems with spider mites before they start, and a strong spray of
water can knock aphids, spider mites, and other pests off plants. Spray
in the morning, so the leaves will dry quickly.
6.
Bt (Bacillus thuringiensis) is a microbial insecticide
that kills only moth and butterfly larvae and is harmless to most other
insects and animals. However, don't spray throughout the garden or excessively.
It won't discriminate between pest caterpillars and those of desirable
moths and butterflies.
7.
Horticultural oil is a more highly refined version of
traditional "dormant" oils applied to leafless trees and shrubs in winter.
Horticultural or "summer" oils control a wide variety of rose pests,
including rose scale and whitefly. These oils also control soft-bodied
pests, such as aphids (and their eggs) and spider mites. Don't use horticultural
oils when you expect temperatures to rise above 90oF.
8.
Insecticidal
soaps. These specially formulated soaps are a key element in
any least toxic pest-control strategy. They are effective against a
wide range of mite and insect pests, particularly soft-bodied insects
such as aphids, immature scale, leafhoppers, mites, thrips, and whiteflies.
9.
Neem oil extracts contain the substance in whole neem
oil that is believed to be the most insecticidal. This product provides
effective control of insect pests, and, unlike many other pesticides,
synthetic and organic, neem is not harmful to most beneficial insects.
