Common Summer Garden Questions

By Ron Dieter, Sunnyfield Greenhouse & Gardens

July 28, 1999

   Now that the growing season is in full swing, I am getting a number of questions about the summer garden. I’ll try to answer some of them here. As with any other hobby or avocation, there is always more than one way to handle any given problem. If what you do works, don’t change your program. If it ain’t broke... you know the old saw.

My hostas are done blooming. Can I cut the flower stalks off?

   Gardeners can remove the flower stalks from hosta plants at any time, whether they’ve bloomed or not. In fact, many "hostaholics" don’t like the flower stalks at all and remove them as soon as they appear. Use a clippers and cut the stalks off where they join the plant.

My garden phlox and monardas have a bad case of mildew. What can I do?

   Join the club. Most gardens with these plants will have some mildew. You can reduce the problem by keeping the area clear around the plants so that air can circulate freely. This method, however, goes against the cottage style which calls for plants to be planted close together. A fungicide can be effective if used as soon as the problem appears or before. Chemicals applied after the problem appears will prevent further damage but won’t clean up the foliage already disfigured.

   I think the best solution is to use mildew-resistant varieties and position these plants at the back of the border where the foliage is behind other plants. Even the resistant varieties can get some mildew but it won’t be noticeable if the plants are behind others in the border. After flowering, the plants can be cut back to 8 to 12 inches above the ground if the foliage is unsightly.

Will I have to dig up my cannas this fall?

   Unlike tulips and daffodils, cannas are not winter hardy here in the Midwest and need to be dug up and stored for the winter. Many gardeners are now using cannas in their patio containers. As long as the containers are kept from freezing, the cannas can be left in them over the winter.

My water lilies have little black bugs crawling all over them. What can I spray them with?

   Those little bugs are probably aphids and are common summer water garden pests. Do not use any insecticides to kill water insects. The chemicals are very toxic to fish. Instead, use your garden hose and nozzle and wash the aphids off and into the water where your fish will eat them. I have seen goldfish in my pond actually "climb" across a lily pad to eat aphids.

My pond water is green and I can’t clear it up. What can I do?

   Algae suspended in the water give it a green color. Algae survive because there are enough nutrients in the water to support its growth. Reduce the nutrients and you will reduce the green color of the water. Nutrients come from fish waste, uneaten fish food, plant fertilizers, and runoff from the lawn. Be sure your pond is not overstocked with fish. Use fertilizer tablets to feed your pond plants, being careful to get them deep into the soil without letting them dissolve into the water. Chemical controls provide only a temporary fix and some can be harmful to aquatic life, so I don’t recommend them. Biological filters are the best cure for green water because they quickly reduce dissolved nutrients.

When should I plant broccoli, cabbage, and cauliflower for fall harvesting?

   Now is the time to set out these plants for a fall crop. Many gardeners tell me that they prefer the flavor of fall broccoli and cabbage over that of plants set out in the spring. Some folks no longer grow a spring crop because they enjoy the flavor of the fall crop so much more.