How to transplant part of a shrub, and options to control potato beetles
"Fielding Questions" columnist Don Kinzler also advises a reader on the best time of year to divide and share rhubarb.
Q: Could you please help me out? What is the name of the beautiful bush in the attached photo? Is there a good time of year to transplant a portion of it? — Diana N.
A: The shrub is a Weigela, most commonly pronounced "why-JEE-luh." The cultivar is probably Red Prince, which is frequently sold at garden centers throughout the region.
The best time to transplant a portion from the outer perimeter is in early spring before the shrub leafs out. Transplanting in midsummer when the shrub is in full foliage and flowering is very risky. There is almost always root loss when transplanting established shrubs, and the reduced root system would have difficulty supplying the relocated shrub with water and nutrients needed for survival.
In the photo I notice a little bit of dead wood, which is common as Weigelas age. These shrubs respond dramatically to heavy pruning in early spring. Every three or four years, prune the shrub back to 6 to 12 inches above ground level, which removes the old, woody branches, and the new growth that quickly emerges is fresh, lively and will bloom with renewed vigor.
Q: I’m seeing potato beetles eating the leaves of my potato plants. I know you can pick the beetles off, but there are getting to be so many. Is there an insecticide that works? — Tom M.
A: Colorado potato beetles, the rounded beetle with black and yellow stripes, can quickly defoliate potato plants. Adults emerge in spring and lay masses of eggs on young potato leaves, which hatch into red-orange larvae, eventually becoming adults.
In my own potato patch, I observed the early adults laying masses of orange eggs on the underside of some leaves. I removed as many infected leaves as I could find, but now I’m seeing the small reddish larvae beginning to feed.
Picking off adult beetles and larvae is a method dating back generations. My dad mentioned having the job as a young boy of picking off potato “bugs” and dropping them in a can of kerosene during the 1920s and '30s before many insecticides were available.
Colorado potato beetles have grown resistant to many of the insecticides commonly used in today’s vegetable gardens. The most effective insecticide currently is the active ingredient spinosad, which is relatively new, and the insects have not developed resistance yet.
Spinosad is an organic material, originating from soil bacterium discovered at an abandoned rum distillery. The active ingredient can be found in several insecticides at garden centers. Apply following label directions.
Q: My neighbor would like to get a start from my rhubarb plant. Do I have to wait until next spring to transplant some for them? — Bob N.
A: There are two times of year when rhubarb can be successfully transplanted: in early spring just as new growth is beginning to emerge from the soil, and around Labor Day in September, similar to when peonies are best transplanted.
There are two ways to share rhubarb divisions. You can dig the entire plant, and separate into divisions, if the plant is old and the center is no longer producing. Select the healthy sections around the perimeter.
If the rhubarb plant is healthy and still productive, and you don’t wish to disturb the entire thing, you can leave the plant intact and in place, and dig a small section from the outer perimeter to share.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at firstname.lastname@example.org. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.