We had a tremendous amount of heat in July and August. Many of our bushes suffered greatly from heat stress. Leaves turned brown, looked wilted and/or just fell off to preserve the moisture in the bush. Extra watering or, better yet, more frequent watering to keep the root ball moist is like CPR.
Leaves will also turn yellow from the heat or be susceptible to black spots. Pick those off the branches and off the surrounding ground to reduce the fungus from spreading. Remember to sterilize your pruners after each bush to reduce the spread of the black spots. Note: We are not totally past severely hot days this summer; protect your roses. Even putting a cover/shade or umbrella over them during the hottest part of the day will save them from the worst part of the heat.
You may also see aphids now. For the majority of cases, just using a high pressure hose spray will wash off those soft bodied pests. Do it every couple of days until the problem is reduced greatly or cleared. Also, make sure your irrigation systems is working correctly so that your plants receive proper moisture.
Rose of the Month: Angel Face
Remember when pruning: Toss plant debris into your city compost bin and not your own compost pile. The Napa City compost center produces higher temperatures to destroy the spores while your backyard pile will not do so. When it comes time to add mulch, consider getting it from the Napa recycling center.
If you have questions about the Fuller Park Rose Garden and the Master Gardeners (MGs) who maintain the rose garden, we are usually in the garden the first Sunday and third Thursday of each month between 10:00 and 12:00, weather permitting.
You can also go to our Master Gardner website: napamg.ucanr.edu for more details.
Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143. Volunteers will get back to you after they research answers to your questions.