Tall grasses, upright shrubs provide screening

Question: I am looking for a dense tall grass to form a barrier between my property and the gravel road. Any suggestions?

Answer: Tall ornamental grasses provide screening from early summer through winter. Most gardeners cut the grasses back in late winter to eliminate the dead foliage. This will leave you a couple of months with no or limited screening.

You might want to add some upright shrubs to the border. They would provide some additional screening throughout the year, especially as the grasses are growing to their full size.

Select an upright shrub that tolerates the growing conditions and road salts (if an issue) and that will fit the space when it reaches full size. Northwind and Heavy Metal switchgrass are cultivars of our native switchgrass (Panicum). These are narrow upright grasses that grow up to 5 or 6 feet tall and withstand the rigors of snow and ice.

Karl Foerster Feather reed grass (Calamagrostis x

acutiflora “Karl Foerster”) is a bit shorter and more narrowly upright. Maiden grass is a popular ornamental grass that comes in a variety of sizes, depending on the cultivar.

Do not plant Miscanthus sacchariflorus or Miscanthus sinensis species because both are invasive. Instead, use one of the vegetative propagated and named cultivars of Miscanthus sinenesis that have not been found to be invasive. Zebrinus, Variegatus, Cosmopolitan and other banded or striped cultivars pose the least risk. If you plant several Miscanthus

sinensis cultivars in the same location, watch for and remove seedlings to prevent the spread.

For more information on these plants, visit my website, melindamyers.com. Go to

miscanthus.cfans.umn.edu for more information on

invasive concerns with Miscanthus.

Q: In a previous column you mentioned you had success growing Imperial Star artichokes. I tried this variety for my third year with no success. I get a beautiful plant for the entire summer, but it never produced a choke head. I mulch heavily in late fall in the hope that it will come back, but it always dies.

A: The key to success is starting seeds indoors in late winter or purchasing transplants and getting them into the garden the first week of June. I failed the first two years, when I didn’t get them planted until the end of June. Last year I made sure to get them in the ground by the first of June.

Artichokes are not hardy in our area, but like you, I tried mulching this winter to see if I could get them to survive. I’m pretty sure our below-zero temperatures killed them.

Q: I have a few different patches of iris and daylilies in my yard. All three patches are becoming overgrown with quackgrass. Is there a way to get rid of the grass or kill the grass without killing my iris and daylilies?

A: Quackgrass is a common problem in ornamental plantings, with no easy solution. Continual removal of the weeds while leaving the desirable plants in place is the only non-chemical option.

You may decide to dig any plants worth saving and then kill the weeds. Edge the bed and cultivate monthly for two seasons to eliminate this and other perennial weeds. Or edge and cover the bed with clear plastic for 6 to 8 weeks during the hottest sunniest part of the growing season to kill the grass and many of the weed seeds.

You can also smother the weeds with black plastic. Cover the edged bed with black plastic for at least one growing season. Make sure you have removed all the quackgrass roots and root-like rhizomes before planting the iris and daylilies in this or any other garden.

A total vegetation killer carefully applied to the leaves of the grass weeds while protecting the nearby daylilies and iris is a chemical option. Concern has been expressed over the health and environmental issues surrounding the most common total vegetation killer, glyphosate. Products like Fusilade II for Turf and Ornamentals can be applied to control grassy weeds in a variety of ornamental beds. Some people have observed injury to monocots like iris and daylilies, while others have not.

You may want to spot-treat the perennial grass weeds and avoid your good plants just to be safe. Always read and follow label directions carefully whether using organic or synthetic chemicals.