Don Kinzler, Published November 15 2013
Fielding questionsQ I thought my bittersweet vine was the American variety (Celastrus scandens), but now I’m not sure, and I’ve been hearing horror stories of the type from the Orient (C. orbiculatus) taking over and strangling large trees.
If mine is the Oriental variety I want to get rid of it. What is a good way to tell them apart?
– Jim Nelson, Walcott, N.D.
A Thanks for giving us the chance to discuss a potentially serious problem. Our native American bittersweet is one of our good, hardy landscape vines.
In 1860, Oriental bittersweet was introduced from Asia as a new ornamental. It has since escaped cultivation, and its extremely invasive habit is choking and girdling trees and shrubs in eastern United States and has been found in locations in Minnesota.
It has further been discovered that some vines sold in the nursery trade as American bittersweet are actually the Oriental variety.
Listed as Zone 4, Oriental bittersweet is not as hardy as the native species, which should limit its spread into our colder regions. However, the two types hybridize in nature, which will probably lead to its developing increased hardiness.
When in fruit, the two are easily distinguished because Oriental bittersweet has yellow bracts on the berries, which are born along the sides of stems. American bittersweet has orange berry bracts born only on stem ends. Leaves of the Oriental type are folded in half inward along the midrib, while American bittersweet cups inward without the distinct fold.
Q I have a small baby blue spruce I got as a seedling for Arbor Day, and it has remained healthy. Last year I covered it with a Styrofoam cone, and it overwintered in good shape. Should I do this again this year?
– Patricia Jasek, Fargo
A Blue spruce is well-adapted, so hardiness won’t be a problem. Its small size makes it susceptible to other injury, so protection will help.
I haven’t tried the Styrofoam cones on evergreens, but I think your idea is good while the seedling is tiny. When it increases in height, it will overwinter fine on its own.
Spruce grows more rapidly if soil is kept cultivated or mulched in at least a two-foot circle. Grass greatly slows evergreen growth if allowed to encroach up to the trunk, especially when seedlings are young.
If you have a gardening or lawn care question, email Don Kinzler at ForumGrowingTogether@hotmail.com. Questions with broad appeal may be published, so please include your name, city, and state for appropriate advice.