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IN THE GARDEN: Evening primrose, black-eyed Susan ready and willing to fill large, sunny spaces

by Janet B. Carson April 15, 2023 at 1:31 a.m.
A reader worries that transplanted from the wild black-eyed Susans and evening primrose plants will overrun this flower bed. (Special to the Democrat-Gazette)

Q: I am writing for advice. I live in a rural, farming area in the North-East corner of our state near Jonesboro. Last summer I dug some evening primrose and black-eyed Susans from ditches in the area. I thought both plants were so beautiful! Now, after reading about them I am concerned they will develop into trouble. I originally planted the evening primrose under an oak tree with spiderwort and catmint. When I saw how well it spread, I started harvesting it and planting it on the banks of the gravel road in front of the house. The ditch had recently been cleaned out and I was hoping the evening primrose would help with controlling any erosion. See how the EP are growing over the rock border [the reader sent a photo]? Can I control them by weed-eating or will the runners invade the yard? Will they choke out the spiderwort and catmint (if they are controllable)? I planted the black-eyed Susans in a perennial bed behind the house. I knew they would reseed and thought I could thin as needed/desired, but now I'd like to know if that was a mistake. I know plants perform differently in different areas, but I am hoping you can let me know what you think. Are they controllable or should I eradicate asap? And finally, if the evening primrose needs to be removed, what would you suggest for affordable ditch bank cover?

A: Showy evening primrose is a beautiful pink wildflower but it can be aggressive. I think where you have them, and with the room you have to grow, let them grow. Learn to recognize them and thin accordingly if they start encroaching into other areas. You know the saying, one man's weed, another man's wildflower. While I wouldn't recommend them for a traditional small yard, I think you should be OK as long as you manage them. Same for the Rudbeckia or black-eyed Susans. They are a great perennial and very popular with bees and butterflies. If they begin to spread too much, just thin them out, keeping space for your spiderwort and catmint.

[Gallery not showing? Click here to see photos: arkansasonline.com/415janet]

Q: Can you help settle a difference of opinion in our household? We have three Eastern red cedars in our yard. In the past, any suckers apparently have been trimmed, maintaining a "clean" lower trunk. Over the past two years, several suckers have started growing. One of us says they should be trimmed so that nutrients are not diverted from reaching the upper branches. The majority vote holder says they should be allowed to grow for the birds. I've included photos to help you weigh in. How should we proceed?

A: The answer is either one you choose. Lower branches are not diverting nutrients from the upper limbs, it is simply a matter of preference — do you want a tree-formed Eastern red cedar, or a bushier form? The choice is yours to make.

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Q: I read your article "In the Garden: Battling bag worms ... ." Was wondering when you recommend spraying trees with BT in Bentonville. The trees were infested last year so want to avoid a problem this year. Thank you for your guidance!

A: I hope you removed as many of the "bags" as you could have this past fall/winter. The insects overwinter inside the bags and emerge the following late spring. While weather conditions do play a factor, typically the larvae emerge in May and begin feeding. As the larvae crawl and feed, they construct the sack or bag around their bodies from the plant they are feeding on, often a juniper or cedar, but they can branch out. These bags protect them from predators and insecticides. They are typically in their crawling/feeding stage for about a month from mid- to late May through June depending on the weather. The key is to apply the insecticides according to label directions once a week from mid-May through June when the bagworms are in their juvenile stage and before the individual bag or sac is constructed. Don't spray the whole yard, just the affected plants. Once you see dried bags in late June or later, the only control is hand-picking.

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 jcarson@arkansasonline.com


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