Tuesday, March 31, 2009

Cleaning Out the Birdhouse

A few years ago, I salvaged a little birdhouse from a teardown across the street. Every spring, we put it out in the back yard, and watch the birds come to investigate. They fly up to the hole, try to squeeze inside, poke their heads out and look around, and then fly away. Sometimes they fight over the rights to the birdhouse.

Last year, I placed it in the midst of some tall plants, and two small birds decided it was to their liking. They built a nest, laid several eggs, raised their young, and left. We sat in the hammock and watched them nonchalantly land near the birdhouse, look around to make sure the coast was clear, and then go inside.

Now that spring's here, I had fun prying open the birdhouse to empty it out. The nest was a thick bungle of twigs, grass leaves, mud, and feathers wedged tightly into the birdhouse.

Monday, March 30, 2009

Are All Trees Created Equal? Choosing Replacement Parkway Trees


For the last seven years, I’ve been nurturing a silver maple (acer saccharinum) seedling that I found growing in the backyard. The Siberian elms (ulmus pumila) that came with our house were nearing the end of their 60-year life span, and I wanted a replacement. We carefully moved the seedling to a spot away from power lines and older trees, and waited. It’s now about 15 feet tall.

When I started researching native plants, I was happy to find out that my little silver maple is a species that is originally from the United States. It is, in fact, one of the most common trees in the country. It’s also on the City of Elmhurst’s list of prohibited parkway trees and cannot legally be planted on the parkway. Silver maples apparently have wood that is susceptible to storm damage, and fibrous roots that can crack sidewalks or invade city sewer systems. My tree is nowhere near a sewer line, sidewalk, or house.

Elmhurst code prohibits nine different types of trees, as well as trees that produce fruit for human consumption. The prohibition seems to have more to do with issues of convenience or safety than ecological concerns. Many of the trees on the list grow quickly, resulting in weaker-wooded trees more likely to drop limbs, have vigorous root systems, or produce fruits that might be “messy.”

Some species on the approved tree list, such as the Norway maple (acer platenoides) and Callery pear (Pyrus calleryana cultivars) are cited by native plant experts as problematic because of their tendency to become invasive, choking out plant life in wild areas.

The Center for Invasive Species and Ecosystem Health notes that non-sterile species of the Callery pear have escaped and are invading natural areas throughout the eastern United States. In Maryland, it is listed as an invasive species of concern, and can be seen covering roadsides there. In 2005, the city of Champaign, IL, decided to no longer allow Callery pears to be planted on public rights-of-way. Though Elmhurst, IL allows the tree, it’s best to plant another type as an alternative.

The Norway maple, like the Callery pear, has invaded natural areas. This tree’s dense canopy and shallow root system make life very difficult for any plants that must grow beneath it. Often, Norway maples are surrounded by bare ground. The National Park Service and numerous other environmental preservation organizations list Norway maple as a species that has invaded forests, fields, and other habitats.

The Morton Arboretum recently recommended Ten Tough Trees for planting in the Chicago area. Of these, several are on the City of Elmhurst’s list of approved trees for parkways. Instead of the Callery pear or Norway maple, consider the hackberry (Celtis occidentalis), Kentucky coffeetree (gymnoclaudus dioicus), bur oak (quercus macrocarpa), or gingko (Gingko biloba) from the Morton Arboretum’s list.

Other trees not on the City of Elmhurst’s approved list, but which are native species, are the swamp white oak (quercus bicolor), sugar maple (acer saccharum), and red maple (acer rubrum). The liberty elm (ulmus Americana) is a variety of the American elm that is resistant to Dutch elm disease, and may be a good choice if you like elm trees.


The City of Elmhurst says on its web site that it plants 300 to 400 trees annually, 90% of them replacement trees, at an average cost of $110.00 per tree. About 250 to 300 trees are removed each year.

Sunday, March 29, 2009

Feed the Caterpillars! Why I'm Growing Milkweed, and You Should Too.

Last summer as an experiment, I bought three milkweed plants from the Morton Arboretum’s plant sale. About a month after we put the young plants in the ground, the kids and I spotted our first striped monarch caterpillar on one of the leaves. Clearly, the butterflies found the plants a welcome addition to the back yard.

This year, I’m planning to strip the sod off the low spot in the back yard that always floods, near the sidewalk, and plant water-loving natives, including more milkweeds. Milkweed (Asclepias) is the only source of food for monarch butterfly caterpillars. Douglas Tallamy, in his excellent book, Bringing Nature Home, notes that many insect caterpillars can eat only one type of plant. Consequently, monarch caterpillars eat only milkweeds—not lawn, hostas, or lilacs.

If we don’t plant milkweed, monarch butterflies cannot produce more monarch butterflies. And at least 11 other types of butterflies need milkweed plants.

Monarch Watch says that monarch butterflies are threatened by humans’ destruction of their habitats. Roads, shopping malls, and suburban housing all have destroyed areas that monarch butterflies need to feed their young and reproduce. Because some people consider milkweed to be a noxious weed, much of the butterflies’ food source has been destroyed. According to the Save the Prairie Society, today less than 1/100 of 1% (0.01%) of Illinois’ original prairies, which covered most of the state, remains. The landscape of Elmhurst, IL, where I garden, probably once looked much like the Wolf Road Prairie.

The Illinois Wildflowers web site lists three different milkweeds that are native to Northeastern Illinois and its original prairies and may be suitable for home gardens. Several milkweeds are on the Wolf Road Prairie’s plant list. I’m listing both Latin and common names here, because plants are often sold at specialty nurseries by Latin name. I encourage you to click on the links to view photos of these beautiful plants, which I can’t publish here without permission.

Prairie Milkweed (Asclepias sullivantii), also known as Sullivant’s Milkweed, grows 2 ½ to 3 feet tall and has broad leaves. The plant produces pink flowers in mid-summer. It requires full sun and moist soil conditions, making it a good choice for that wet spot in my backyard.

Butterfly Milkweed (Asclepias tuberosa interior) grows 1 ½ to 3 feet tall and resembles a small bush. The 2- to 4-inch flowers appear in midsummer, and the plant produces 4-inch seed pods. The long-lasting and colorful flowers make this a showy plant. The plant needs full sun, and well-drained soil. I bought this plant at the Morton Arboretum’s plant sale last year.

Whorled Milkweed (Asclepias verticillata) requires full sun and dry soil. The plant, 2 to 3 feet tall, is unbranched and has 2- to 3-inch clusters of white flowers. It originally ranged through most of Illinois, except the far south part of the state.

Purple Milkweed (Asclepias purpurascens) is an unbranched plant about 2 to 3 feet tall that I bought last year at the Morton Arboretum plant sale. Leaves, as for other milkweeds, are dramatic: 6 inches long and 3 inches wide. The plant does well in well-drained soil and full sun to light shade.

Swamp Milkweed (Asclepias incarnate) grows well in moist to damp soils and full sun to part shade. It is a good plant for a spot that floods regularly. It grows 3 to 5 feet tall and produces clusters of pink, white, or light purple flowers. The plant’s roots are specialized for growth in wet soils.

Common Milkweed (Asclepias syriaca) may be too invasive for many home gardens.

Because these plants are unlikely to be available at the local Home Depot any time soon, gardeners must rely on other sources to obtain them. Online nurseries, such as Wisconsin’s Prairie Nursery and Minnesota’s Prairie Moon Nursery are mail-order sources but may not carry local genotypes—plants reproduced from stock originally growing in Illinois prairies. The Natural Garden, Inc., a local nursery in St. Charles, sells several types of milkweed—Swamp Milkweed, Common Milkweed, and Whorled Milkweed.

Wednesday, March 18, 2009

Sprouting Native Plant Seeds Indoors

I'm very excited. I just made the rounds of my seedling flats, and it looks like they are finally sprouting.

I've been growing simple annuals and vegetables from seed indoors for a while, especially tomatoes. But I began experimenting with starting seeds of native plants indoors last winter and am doing it again this year.

Really, the easiest way to start native plants from seeds is to sow them outside in the fall. But I haven't been organized enough to order them in time to do that. So instead, I followed the instructions in Prairie Moon Nursery's useful cultural guide, which comes with my seed order.

Most of the seeds need to be cold stratified. I do this by filling little plastic Ziploc bags with damp vermiculite, adding the seeds, and storing them in the refrigerator for the specified amount of time, usually 60 days. I then transfer them to flats and put them in a warm spot, like on top of the refrigerator, to germinate them.

This year, the copper shouldered oval sedge and sideoats grama came up quickly. They're now growing in my front window. The wild hyacinth and Virginia bluebells weren't doing as well. I'd given up on them but left them going and it looks like maybe, just maybe, they are starting to sprout.