Q: This last summer one of my new roses developed blackspot on every leaf. I removed all the affected leaves and sprayed. Do winter temperatures in the Boise area kill blackspot or shall I look forward to fighting it in the spring?
A: Blackspot is a fungus, and is spread by spores via splashing water. If leaves are moist when a spore splashes or blows onto them, blackspot develops. Therefore strict sanitation is advised to control blackspot. Do not compost affected leaves, but carefully gather them and put them in the trash.
We seldom have that problem in our dry climate, but it does happen when humidity or watering practices result in damp leaves. Therefore it's a good prevention to lay a mulch under your roses that will prevent splashing water. I don't think winter will kill the spores. They are rather ubiquitous anyway. If prevention doesn't work, use a fungicide to kill the blackspot.
Q: Powdery mildew was a problem last fall on several of my roses. If I set up a routine of spraying every two weeks, would this eliminate this disease? This is the first summer I've had this mildew problem with these established roses.
A: Powdery mildew often occurs when plants are crowded together and there's poor air circulation. But this is a fungus disease too, and depends on humidity and moisture on leaves to get a foothold. Be sure you water early in the morning so leaves have a chance to dry before cool evening arrives, install a non-splashing mulch, and if the disease shows up, spray a fungicide as often as it comes back.
Some people are using a spray of 1/3 or 1/4 skim milk to 2/3 or 3/4 water on fungi such as blackspot and powdery mildew, and reporting success in killing the fungi.
Q: We've turned our vegetable garden into one for ornamental plants, but still want to grow some vegetables for our own use. Could we use containers?
A: Yes, you can, but you will have to be attentive to their water needs. Plants such as tomatoes may need to be watered more than once each day. You can buy polymer crystals at garden stores in this area that will store water then release it to plants so you may get by only watering once per day. I'd recommend the book, "The Bountiful Container" by Rose Marie Nichols McGee and Maggie Stuckey.
If you plan to adapt containers for plant use, such as those white buckets you get cheaply from bakeries or from Hap Tallman's store, instead of drilling holes in the bottom for drainage, drill holes in the sides, an inch or two above the bottom for drainage. It works better.
Q: What sort of vines will grow well in shade?
A: Some varieties of Clematis will grow and thrive in dappled shade or at least three or four hours of direct sun per day. Zepherine Drouhin, a lovely climbing rose, tolerates some shade. For deep shade, perhaps ivy would work best. There are very interesting variegated ivies available now.
Q: Is there an alternative to dragging heavy hoses around?
A. This question is from my amputee friend in Atlanta, so she's still faced with watering. Look forward to the day when you can either have your husband install or hire someone to install a sprinkler system. Until that time, shop carefully, and heft the hoses you're looking at. Lightweight plastic hoses often kink. The rubber hoses are best, but they're heavy. If you find a light one "guaranteed not to kink," take a photo of it and pin it to the guarantee.
Q: I've heard you can stretch moss plantings by mixing moss with buttermilk in a blender and painting it on surfaces you want to grow moss. Can you do this with lichen? (This question was asked by a Boise-area reader some time ago, and I can't find her post. I didn't forget the question, however.)
A: I asked this question of Roger Rosentretter, with the BLM in Idaho, but an international authority on lichen. He said you can do that so long as you keep it well moistened until it takes hold. Mist it often. As he said, it's easier to do in a humid climate.
Question: Should I put fireplace ashes on my garden?
Answer: No. They will increase the alkalinity of your soil. Our soil is very alkaline to start with.