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Sunday - June 21, 2009

From: Lake Forest, IL
Region: Midwest
Topic: Water Gardens
Title: Understory plants for Lake Forest IL
Answered by: Barbara Medford


We have a large mostly hardwood lot in Lake County. It floods when it rains hard and remains damp most of the year due to the amount of shade and clay based top soil. Besides the hardwood trees and a few spruce trees the undergrowth appears to mostly ferns, some non-native monkey grass and some other ground cover. What flowering bushes or flowers would be good to add to the lot as there is a lot of open bare ground? Something that would also be a food source to birds and animals would be of interest as well.


A shady, wet environment is going to call for some ingenuity and maybe some work, before you plant anything. The clay soil and hard rains are two strikes against most plants. The first thing you need to do is assess the drainage. Where does water stand the longest? Are there any barriers (natural or otherwise) that could be moved to permit better drainage? When you are ready to commit to planting in certain areas, you need to do everything you can to improve the drainage there. The first, best move is to work a lot of compost or other oganic material (not peat moss, please) into the selected areas. Compost is like a wonder drug; it adds nutrients to the soil, it helps make trace minerals in the soil available to the plant roots and, most important, it keeps the roots from drowning because of water standing on them. Raised beds are another possibility; read this article from Popular Mechanics magazine, How to Build and Install Raised Garden Beds.

The next criteria you need to consider before you select plants is the amount of sun available to each area you have designated for planting. The plants in our Native Plant Database are all categorized as to their tolerance of sun (6 or more hours of sun a day), part shade (2 to 6 hours of sun) and shade (less than 2 hours of sun). It would be very useful for you to make a daily or weekly record of how long the sun is on each of your prospective planting areas. This will change slightly, of course, through the seasons as the position of the sun and the length of daylight change.

As you can see, selecting plants is not the first step, but the last in a situation like this. Start out by reading this website Fighting Drainage Problems by Landscaping with Native Plants. The plants listed are not all necessarily native to your area, but it does refer to the Northeast United States, so many of them could be. Have you considered creating a pond area in your landscaping to handle some of the drainage? From previous answers by Mr. Smarty Plants, we found some answers on screening plants around a pond in Illinois. The situation was somewhat different, but the plants would still apply. Construction of a pond is way out of our comfort zone, but take a look at this University of Virginia Cooperative Extension website on Pond Construction: Some Practical Considerations

At last, some plant suggestions. You can go to our Recommended Species site, click on Illinois on the map, and then Narrow Your Search by looking for plants that can take shade (and you can check both shade and part shade) and wet soil. Start out by searching on herbs (herbaceous blooming plants) under Habit, and then you can search on shrubs, ferns or grasses. We are going to make a couple suggestions from each category, and you can expand on that. You should note the soil requirements, if the plant will tolerate clay, if it needs acid or alkaline soil and so forth. Because you are interested in attracting wildlife, you want to select plants that are either larval hosts or nectar sources for bees and butterflies, have berries or provide shelter and nesting materials. For some more tips on wildlife gardening, read our How-To Article on Wildlife Gardening. On the list below, follow the plant link to the webpage on that plant to find out the wildlife benefits and other features.

Herbaceous flowering plants for Illinois

Asclepias incarnata (swamp milkweed) - blooms pink, purple June to October, sun or part shade

Lobelia cardinalis (cardinalflower) - blooms red May to October, sun, part shade or shade

Shrubs for Illinois

Cephalanthus occidentalis (common buttonbush) - evergreen, blooms white, pink June to September, part shade or shade

Viburnum opulus var. americanum (American cranberrybush) - blooms white May to October, part shade

Grass, grass-like plants for Illinois

Calamagrostis canadensis (bluejoint) - sun, part shade or shade

Typha latifolia (broadleaf cattail) - evergreen, sun or part shade

Ferns for Illinois

Athyrium filix-femina (common ladyfern) - part shade or shade

Osmunda cinnamomea (cinnamon fern) - sun, part shade or shade

Asclepias incarnata

Lobelia cardinalis

Cephalanthus occidentalis

Viburnum opulus var. americanum

Calamagrostis canadensis

Typha latifolia

Athyrium filix-femina

Osmunda cinnamomea






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