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In my last article, I wrote about plants that can be planted/transplanted in early fall. Since trees and shrubs were included in those plants we can work with in the early fall, you may want to plant something that will give you beautiful color next fall.

Japanese maples are noted for their brilliant fall color. Unfortunately, here in Minnesota, these beautiful trees are rated as a USA Zone 5, and therefore do not over winter well in our Zone 3/Zone 4 area. Stan Hokanson, Assistant Professor in the Department of Horticultural Sciences at the U, wrote about a Japanese-like maple that will survive our winters. One of my fellow Master Gardeners, who took Prof. Hokanson's class last fall, remembers his enthusiasm about the tree in lecture.

This is a small tree or shrub, commonly referred to as a Korean Maple or Purple-bloom Maple, and is generally listed as Zone 4 hardy. It has survived the cold winters of Bismark, ND (Zone 3) without damage, at temperatures as low as -43 F. Its genus/species name is 'Acer pseudosieboldianum'. Thankfully, I can write about it without having to pronounce it!

Its native habitat is Manchuria, Korea and China. There it grows in mixed forests on well-drained, stony soils, where it can attain a mature height of 15-25 feet with greater width. The species is openly branched with grey, black-striped branches. The leaves come out with a reddish tinge that turns to a dark green with some white on the underside. The leaves are 4-6 inches wide, with their fall colors described as brilliant yellow, orange and/or red. They hold their leaves throughout the winter, falling off when new spring growth begins.

As with any garden plant, the species is not problem free. Some test lots report an occasional tree being less vibrant in color and some winter damage. The Korean maple is thin barked, rendering it susceptible to mechanical damage and winter sunscald, especially where the mechanical damage appears. Damage to the trunk and stems can also provide sites for disease infections.

The main liability of the species appears to be its susceptibility to canker disease, which enters the tree at wound sites, causes dieback of infected branches or stems. Management strategies include maintaining plant vigor with adequate water and fertilization. Most importantly, remove and destroy infected twigs and limbs to prevent the spread of any disease. Fungicides can be used in conjunction with pruning or at any wound sites to protect against infections, although there are no fungicides labeled for such use.

While the species tolerates full sun and wind, it will perform much better with protection from the afternoon sun and prevailing winds. They grow well in heavy shade, but like all plants, will develop the best color when sited in sunnier locations.

Now that I have you all excited about planting a Korean maple, Dr. Hokanson did state that they are still improving its cold hardiness and resistance to canker disease. If you do plan to plant the species in the near future, make sure you deal with an established and trusted nursery or garden center.

Submitted by

Jerry Vitalis

Chisago County

Master Gardener

There are three remote drop off sites for samples in the county: Mannions Greenhouse and Floral in Rush City, North Branch Floral and Federated Coop (Cenex) on Highway 8 in Chisago City. There will not be a Master Gardener on site, but these businesses have agreed to hold the samples for pickup.

There will be Master Gardeners on site to answer your questions Thursday evenings from 6-8 p.m. at the Chisago County Hazardous Waste facility in North Branch.

The Lindstrom Farmers Market is now open. There is a Master Gardener there from 8 a.m.-noon every Saturday.

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Other ways to access information:

www.extension.umn.edu/county/chisago

Check out the “Hot Topics” box in the middle of the page for current Chisago County Master Gardener news and events. You can also click on “Ask a Master Gardener” next to the cute little flower on the right hand side of the page. Here you can search 1000s of answers from Master Gardeners around the state. If you don’t find your answer, you can submit a question online or search for University publications.

Bell Museum of Natural History

For information about snakes, skunks, raccoons or other wildlife around your yard, call the wildlife information line at (612) 624-1374 or www.bellmuseum.org.

Master Gardener voice mail: 651-237-3080

Leave a message and a Master Gardener will call you back within a couple of days.

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