Ask a Master Gardener: Ornamental Grass is Easy to Maintain and Aesthetically Pleasant – Brainerd Dispatch

Ask a Master Gardener: Ornamental Grass is Easy to Maintain and Aesthetically Pleasant – Brainerd Dispatch

Dear Mr. Gardener: I would like to plant a row of tall ornamental grasses along a curve in my driveway. What do you recommend?

AnswerOrnamental grasses are low maintenance, easy to grow, grow quickly, are usually free of disease and insects, and are aesthetically pleasing. What’s not to like? Most ornamental grasses grow best in full sun and many do well in open, exposed areas where other perennials may be damaged by wind gusts. They add beauty, shape and texture to your winter landscape, so don’t cut them to the ground until spring.

Here are some recommendations:

  • Feather reed grass (Calamagrostis) is a wonderful cool-season grass that makes an excellent vertical plant. It is hardy to zone 3. You see it often in commercial landscapes because it grows well in many soil types. The very popular Avalanche, Eldorado, Overdam and Karl Foerster reach 60 inches in height and 18-24 inches in width at maturity.
  • Calamagrostis brachytricha is a fall-blooming Korean reed grass that is hardy to zone 4, but has been thriving in my Brainerd area garden for years. This is one of the few ornamental grasses that tolerates some light shade but prefers full sun. Korean reed grass reaches 48 inches tall and produces 12-inch shafts with a pinkish-purple tinge in August.
  • Little Bluestem (Schizachyrium scoparium) is a zone 3, warm-season prairie grass that forms a dense clump. Blue Heaven was developed by the University of Minnesota and released in 2008. It grows 40-48 inches tall and 25-30 inches wide. It has stunning fall color. The color of the foliage ranges from dark blue to burgundy in the summer, then turns to red and purple in the fall. This grass needs good soil drainage in order to thrive.
  • Golden Sunset-Yellow Prairie Grass (Sorghastrum nutans) is another University of Minnesota ornamental grass released in 2020. It resembles Karl Foerster’s feather reed grass and is hardy in zone 3. Its shape is tall and straight (reaches 48-72 inches tall at maturity) It does not fall and is 36 inches wide. This herb features olive green leaves with numerous yellow and bronze-gold flowers.

Dear Mr. Gardener: I bought some potatoes and when I cut them in half to boil them there was a star-shaped hole in the middle with some browning around it. Can you still eat it?

Answer: Not only will you find this phenomenon in potatoes purchased at a store or farmers market, but gardeners are also discovering it from potatoes grown in their vegetable garden. This star cavity or lens inside the potato is called the hollow core. According to the USDA, “The cause appears to be a sudden change in tuber growth rate that usually occurs after a period of stress.” We have seen sudden changes in growing conditions this summer with drought and then heavy rains. Some research has shown that if the hollow core had brown edges, this occurred early in the potato’s growth, and those that were not dark occurred near the potato’s harvest. For those gardeners who grow potatoes in their vegetable gardens, it is very important to maintain soil moisture during dry periods. Yes, you can still eat it. The hollow core does not affect the taste, quality or nutrition of potatoes.

Dear Mr. Gardener:Should Astilbe be dead?

AnswerDeadheading Astilbe is an aesthetic issue. If the brown flower head bothers you, cut the flower back to the first set of leaves. If that doesn’t look good, cut it back down the stem to the next set of leaves. Removing spent flower heads will not expand or promote more flowers.

Dear Mr. Gardener: I have a magnolia tree in my house in Minneapolis. There are many pinkish-orange to brown dome-shaped protrusions on the branches. I’m not sure if it’s possible, but it seems to attract wasps. What is it and what should I do?

Answer: You appear to have magnolia scale, an insect problem that typically appears in late July and early August when the nymphs mature. The aphids produced by the scales attract ants, wasps and other insects. According to the U of M, magnolia populations can build up quickly within a single generation. Insecticide treatments should be performed in the same season in which they are observed on the plant. Use horticultural oils in late fall and early spring to suffocate overwintering nymphs. Additionally, apply a systemic insecticide in the spring.

Dear Mr. GardenerConeflowers have odd-shaped and misshapen flowers. Is this some kind of disease?

Answer: Unfortunately, your coneflowers seem to have a disease called star yellow. Starburst yellow tends to be more prevalent during hot years, which explains why you’re getting it this year. It is spread by leafhoppers, so you will need to remove infected plants immediately. If some of your plants don’t show symptoms, you don’t have to remove them, but monitor them. Remove anything that starts to cause symptoms. Do not put infected plants in your compost.

You can get answers to your garden questions by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. Our Master Gardener will return your call. Or email me at and I will answer you in the column if space permits.

Master Gardeners are trained at the University of Minnesota and volunteers are certified at the University of Minnesota Extension. The information in this column is based on university research.

    (tags for translation) Garden Tips for Growing in Minnesota 

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