Pruning and winter maintenance
From the end of October to beginning of November, the hybrid teas and floribundas, used as male or pollen parents are pruned to about 6 inches (15 centimeters) while selected OGRs are only cut back lightly. All plants, including the hardies, are sprayed with a dormant oil and sulfur combination. Soil is then hilled up around each tender plant to cover the above ground stems as much as possible. Thermal blankets are not used since the under material seems to attract mice. More detailed information on pruning is available from a number of books, publications and the internet.
Maintenance
During the long winter months we take care of the seeds harvested from the summer’s pollinations and also search the catalogs and the web for new introductions. When Spring arrives and the earth has thawed, the soil around each plant is removed and a further light pruning to remove diseased or broken canes is given to all the rose bushes. Fallen leaves from the previous season’s growth are collected and burned or placed in the garbage. These leaves are never mulched as they may be diseased. Dormant oil combined with sulfur is again applied to the bare canes to lessen the number of fungal spores, fruiting bodies and insect eggs.
Spraying
After the buds have broken and leaf growth occurs, parental rose bushes and others known to develop black spot and/or mildew are sprayed with Funginex, a systemic anti-fungal chemical. Most other fungicides and insecticides are no longer available to the gardening public in several provinces in Canada due to their toxicity, so an earth friendly control approach will now have to be undertaken. More recently, effective black spot/mildew biological fungicides have been introduced to the market in the United States and approved for use in many other countries. Northern Hybrid Roses has not tested these new fungicides to date. In the meantime, sulfur can be used alternately with Funginex. Baking soda at the rate of 1 tablespoon per gallon of water with the addition of 1 or 2 drops of a pure soap or dish detergent has also been reported to control black spot.
As well, most toxic insecticides have been removed from the market, so Bacillus thuringensis will be used in an attempt to control caterpillars. There are a number of biological products already on the market to control other insects which attack roses.
Even with biological products, an individual should dress in the recommended attire in order to protect oneself. Information is generally available in Grower Pesticide Safety Course Manuals published in the USA, Canada and other countries.
Fertilizing and watering
With the emergence of leaf growth on the plants our fertilization program begins. Granular rose fertilizer (6-9-6 - ½ cup per mature plant and a handful for a small plant) is applied around the base of each plant. As leaf growth develops, alternate applications of soluble feedings are applied about every 15 days until the end of July: (a) 20-20-20, magnesium sulphate (Espon salts), and chelated iron, (b) 18-24-16, fish emulsion and chelated iron. Again, care is taken when applying the amount of iron as too much can cause iron toxicity to the plant. Roses seem to love water every bit as much as fertilizer so they must be well watered (1 gallon or about 4 liters) or more on a weekly basis. In the hot dry weather experienced during the past summers, plants had to be watered two and occasionally three times a week. Drip irrigation is the most effective way to save water and is very beneficial to the plants. A small amount of soluble rose fertilizer (18-24-16) can be added to the irrigation water two or three times a week.