Q This exotic looking plant grew up spontaneously in my vegetable garden. I would like to know what it is.
A The plant in question is one healthy canna plant. It should produce a showy bloom in a possibility of several colors. Cannas are long-lived perennials in most of our state, but can sometimes get nipped in Northwest Arkansas winters. It thrives in full sun.
Q I hope you can help identify the problems with the established hedge that looks like a big portion has died and a diseased or infested Rudbeckia. I did not notice any insects or evidence of insects on the leaves of either plant. If either problem is treatable, what should I do or use?
A The shrub looks to me like it has been burned. Was anything really hot close to it, or was something sprayed? The pattern does not look like a disease to me. Keep an eye on it and see if it spreads. The Rudbeckia does look like it is suffering from a disease, but it looks like it is blooming fine. There are fungal and bacterial diseases that can affect Rudbeckia. Avoid giving the plant too much water. Try to keep the foliage as dry as possible and cut out the heavily damaged leaves. If problems persist, take a sample to your local county extension office; they can send it to the disease lab for diagnosis. You might want to call before you go, to see how they are handling foot traffic. A thorough fall cleanup this year will also be helpful.
Q In one of your recent columns, you told about a fertilizer you sprinkle on your outdoor potted plants and water in, doing this about every two weeks. What brand do you use? When I went to a local nursery, they sold me some Osmocote which I think is a great fertilizer, but you put it on every 4 months. I can remember every two weeks but certainly will forget every four months. I also forgot the three numbers in your fertilizer and don’t have the article anymore.
A All complete fertilizers come with 3 numbers on the bag or box. They represent nitrogen, phosphorous and potash. An even mix is what I find works best for me. I use a variety of brands. I usually don’t buy anything higher than 10-10-10 for my container plants. Right now, I have two bags of 8-8-8 and some of 4-6-3. I love Osmocote for a slow-release fertilizer, and I do use it when I am planting my containers and the annuals and perennials in the ground. Since I water so frequently, I follow up in the summer with a faster acting granular form of a complete fertilizer. If you have a small number of containers, water-soluble fertilizers also work, but I have a large yard and I fertilize a lot, so I would not want to keep mixing and pouring. Look for something evenly balanced. I know many gardeners want to go with a fertilizer with a high middle number for more blooms, but phosphorous (which is the middle number) stays in the soil fairly well, while nitrogen is needed to keep things growing well and a good green color.
Q We have a beautiful hibiscus, bought a couple of years back. I overwinter it in the garage. This year, it seemed to struggle for a while. I promised to quit singing to it, and it perked up. We have gorgeous yellow blooms. They take a week or so from first sign of bud and produce magnificent blooms, but they last one day only. The next morning, they are rolled up similar to the ones about to bloom. What can I do to make them hold on?
A Unfortunately, that is the nature of the beast. Most tropical hibiscus flowers only last one day. A few new varieties can last up to 3 days, but that isn’t common. If you keep your plants well-watered and fed, they should have continuous flowers in the summer months. Since you do save yours from year to year, remember they bloom on new growth, so a really woody, older plant will have fewer blooms. Repot it every spring and prune it to encourage better flowering.
Retired after 38 years with the University of Arkansas Cooperative Extension Service, Janet Carson ranks among Arkansas’ best known horticulture experts. Her blog is at arkansasonline.com/planitjanet. Write to her at P.O. Box 2221, Little Rock, AR 72203 or email