I would like some general advice on how to be successful with my new plantings after having lots of problems over the last couple of years. Some of the plants I have installed have not been performing well.
— Jeremy Anderson, Libertyville
Welcome to the 2024 gardening season! Living in the greater Chicago area, we need to pay attention to our particular gardening needs. Plants that do not perform well in the garden can be very frustrating. Different gardeners may give conflicting advice that can make determining a course of action even harder. Here are some general considerations. First, select the right plants for your design objectives and for your garden’s growing conditions. It is always better to provide the conditions a plant prefers rather than ones it simply tolerates. I see many home gardeners with plants that are not suited well for what the plant needs and how the plant grows. For example, ‘Autumn Joy’ sedum likes sunny and dry conditions, while astilbe likes shade and moist but well-drained conditions. Weigela is generally easy to grow and does best in full sun. Viburnums tolerate light shade but flower less and become thin if the shade gets too dense.
Selecting the wrong plants for your garden’s growing conditions results in poor plant performance and extra maintenance. There are a variety of soil types in the Chicago area, ranging from sandy to heavy clay, and your garden’s soil conditions affect the growth of your plants. A river birch develops chlorotic (yellowed) leaves when grown in heavy clay soils that have a high pH. River birch prefers moist conditions but will adapt to drier sites. There are other trees that are more tolerant of these growing conditions, so choose those. There are some maintenance practices that can help plants that prefer acidic soils. You may decide to amend the soil around plants with elemental sulfur to reduce the soil pH. However, for the long term, it’s probably best to choose a different tree.
Soil conditions are essential when siting plants. If you hear that a plant needs these conditions, we recommend paying attention. These conditions include dry; moist but well-drained; and wet and poorly drained. Spreading yews do not do well in wet soil. Common red twig dogwood (Cornus sericea) tolerates wet conditions and is easy to grow, but flowering dogwood (Cornus florida) is much more difficult to grow in the Chicago area.
Good site preparation, proper planting techniques, and proper maintenance will improve your success too. Sites with new construction often have heavily compacted soils that need to be loosened up and amended with compost before planting. Sites with new homes may have very little topsoil left. Trees are often planted too deep — you should be able to see the root flare just above the ground. I like to plant 2 to 3 inches high in heavy clay soils. The base of the tree’s trunk widens out at the root flare. The root flare can be inches below the top of the burlap of a balled and burlapped tree. The stress of planting a tree or shrub too deep may not become visible until the plant has been in the ground for a few years.
Choosing the correct plants for your garden’s growing conditions and properly installing and maintaining them will keep your garden healthy and attractive. Be sure to check with the Chicago Botanic Garden’s Plant Information Center for help. You may also find answers at local garden centers and landscaping companies. The Regenstein School at the Chicago Botanic Garden offers a wide variety of gardening classes. Knowing the plants you currently have and the growing conditions in your garden will help a gardening expert provide you with the best advice.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.
