If you choose a variety with known disease resistance, rather than being random or just selecting from what’s available for sale, you will have success. Local rose societies such as Seattle or Tacoma compile lists of recommended disease resistant roses. These lists will be available at my talk. Start with free, local information. Remember that the first year is critical with keeping your plant watered during our June-August drought. Please take few extra reading minutes and read the article I wrote for the January/February West Sound Home and Garden.
Identify the problem with your roses
Before taking any action, be certain that you identify the insect or fungal disease and use the Integrated Pest Management (IPM) approach to a pest free garden. If your roses do not have to be perfect, then you can tolerate a certain amount of insects. If you want exhibition quality roses, then you may have to rely on more chemical control.
Fungal diseases do not go away when no action is taken. Once a leaflet shows disease, it will not go back to the way it was before infection. You can begin by cutting off (not tearing) the infected parts of the bush. If you wait too long, the plant will naturally shed the leaves (defoliate) but in the interim, the fungi spores continue to multiply and blow around your yard.
Below is an example of blackspot
Below is an example of Powdery Mildew
Below are examples of the early infection of Botrytis, also called gray mold
Roses will uptake maximum nutrients when the soil pH is between 6.0 and 6.5. This reading changes in different locations of the garden. Other factors that change pH include use of chemical fertilizer and when the pH is tested, before, during or after the rainy season. West of the Cascades, the native soil tends to be acidic. (East of the Cascades the soil is alkaline) My Kitsap garden beds have had readings on October 2, 2016 between ph 4.5, pH 5.0 and pH 6.2. I applied granulated lime according to directions on the bag after these readings. You may have heard that lime is a slow acting soil amendment. I waited three months, until late December, to find pH in all rose beds to be pH 6.3 and pH 6.6.
I did not think this chart would project very well in the Rainier Room and even if it were projected, it seems to me to be something to study to fully understand.
The excitement is building now that the holidays are behind us. The 2017 Northwest Flower and Garden Show will be here before we realize it. This is the traditional kick off to spring in Seattle. Speakers and vendors crowd the convention center for a jam packed five days of garden glory. I love the display gardens to get inspired for the growing season. This year I will be speaking about roses on Saturday to kick off the the bare root rose growing season. I am so excited I can hardly wait. My program is finished and gets tweeked every week.