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Wednesday - October 08, 2008

From: Kansas City North, MO
Region: Midwest
Topic: Pollinators, Pests, Erosion Control, Shrubs
Title: Landscaping for slope in Kansas City
Answered by: Barbara Medford


We have a down sloping back yard and patio on the lower area. We need some water absorbing plants near the foundation and some in the front of the house, where water isn't a problem. We are allergic to bees and wasps. What plants can we use around the foundation both in the front and back of the house? Also, what should the slope be away from the house? We are new to gardening.


This is one of those questions where we could write a book in answer. Some of your questions we really can't answer fully because we don't know what the sunlight amounts are, or the soils. What we can do is point you to some of our How-To Articles on beginning gardening, plus give you help in finding the plants that will work for you in our Native Plant Database.

First, some articles for beginners (and pros, too). Under "Why Natives?", learn why we at the Lady Bird Johnson Wildflower Center will recommend only plants native to North America and to the area in which they are being grown. These plants, because they are already adapted, will require less water, fertilizer and maintenance. Next, under "Gardening with Native Plants," read "A Guide to Native Plant Gardening" and then "Gardening Timeline". 

Just to touch on the bees and wasps subject; both of these are beneficial insects, and ordinarily will not bother you, if you don't bother them. Bees are important pollinators, and we want to encourage them to continue to work the gardens. Unless you just antagonize one, or stick your hand into a swarm, they are too busy with their work to be bothered with humans. Wasps feed most of the time on harmful insects and flies, and only part of the time, like now, in the Fall, do they become a problem, because their normal food sources have run out. They are attracted to sugars, and love picnic grounds. They do build nests that sometimes have to be eliminated because they are in a location where coming in contact with humans is a problem. Please read this previous answer concerning yellow jackets, and ways to deal with them. It's probably not going to freeze as soon in Missouri as it is in New York State, but at least the end of this year's threat is in sight.

Next, the question about the slope away from the house. We're a little unclear on what you mean, if you are wondering what the degree of slope should be, or how to deal with it. You probably don't have a lot of control over what the degree of slope is; your main concern is to keep water from washing down into the back of your house, carrying mud with it. The best thing for erosion of that sort is to plant grasses. With their fibrous roots and ability to hold their positions nearly year-round, native grasses are the most useful. We are assuming that some sort of ground cover or grass is already in place, and you will have the opportunity over the winter to observe how well this works and what needs adjustment.

To begin with the back, where there is apparently some problem with water standing, try to find ways to drain that water away or at least make the soil more able to drain. If the area is directly beneath the roofline of the house, some sort of guttering, moving the water off to an area where it can drain naturally, would be a big help. Most plants, even those tolerant of wet soils, cannot tolerate having their roots in water a lot of the time. The roots will drown, and the plant will die. If the soil is sandy, it should drain pretty well on its own. If, however, water stands on the surface for half an hour or more after rain or watering, it is probably clay, which does not drain well. Mixing some organic material, such as compost, into that clay will improve the texture and drainage.  If you really want to find out about standing water problems, read this article on Drainage. It's probably going to tell you more than you ever wanted to know, but at least it's a start.

Okay, plant selection for around your house. Again, because we're unsure on what you're looking for in terms of evergreen or deciduous, bloom, amount of sun available, etc. we aren't prepared to recommend specific plants. We'll begin with our Native Plant Database, Recommended Species. Click on Missouri on the map, which will take you to a list of native plants recommended for your area. Go to Narrow Your Search, and select, for instance, Shrub on the "Habit" drop-down. Choose the Light Requirement category that best represents how much sun the area has each day. and finally the Soil Moisture. It sounds like your back area at the house should be either "Moist" or "Wet". Now click on search and you'll get a list of shrubs that fit those qualifications. We gave this a trial run, asking for Shrub for Habit, Sun (6 or more hours a day) for Light Requirements, and Moist, soil looks and feels damp, for Soil Moisture. This gave us a list of 6 shrubs to consider. By following the link from the botanical name for each, you can read a webpage with height, blooming time, deciduous/evergreen, etc., and at the bottom of the page, find a Google link for still more information. We selected Physocarpus opulifolius (common ninebark), a deciduous, blooming shrub, just as an example. You can play around with this, selecting on Herb (herbaceous plant), indicating if you want an annual or a perennial, Tree, Vine, Fern, whatever you're interested in, with different sun exposures, soil moistures, etc. Another resource for local information on gardening you should look into is your County Extension Office. Since we didn't know which of four counties you are located in, we selected the University of Missouri Jackson County office for you to check out. When you get the home page, click on "Home and Garden" and find out what kind of help they have available for you.

Now, where to begin, or perhaps when to begin? On the USDA Hardiness Zone map, it looks like you are in Zone 5b. It would probably be better to wait until the last average freeze date to start planting, so you have the winter to make plans, perhaps correct the drainage, amend the soil with compost, etc. Go to our Native Plant Suppliers section, type in your town and state in the "Enter Search Location" box and you will get a list of native plant nurseries, seed companies and landscape consultants in your general area. They can help you even more with plant selection and instructions. Happy gardening!




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