Bring tender plants indoors soon
Nights are growing cold and it is time to prepare to bring tender plants such as tropical houseplants indoors. The average first frost at the Chicago Botanic Garden is Oct. 15, though it is typically later in Chicago.
These plants will acclimate to cooling weather to some degree, so they can cope with gradually declining temperatures in early fall. When nighttime temperatures begin dropping below 40 degrees, however, it is time to bring in any tropical plants.
If there has been a long spell of warm weather and a sudden dramatic drop in temperature is predicted, you may want to bring houseplants indoors for the night. Tender plants also can be protected from light freezes by covering them with sheets, plastic or boxes.
Although most people do not think of installing holiday lights until after Thanksgiving, warm fall days are great for the task. It is much easier to wrap branches with strings of lights on warm days in mid- to late October than during cold days in late November or early December. The Chicago Botanic Garden staff starts installing strings of lights in early October.
Use LED lights to save on power and be able to use more strings on a circuit. Be sure to use power cords that are rated for outdoor use.
Buy warm color white LED lights if you want to match the color of the commonly used white incandescent lights. Cool color LED white lights will have a blue cast to them.
Wrap branches of your trees with strings of lights individually to accent the tree's form.
When building walks, driveways and patios, it is best to avoid using gravel with crushed limestone to create a base for pavers or bricks. Limestone increases the alkalinity of adjacent soils and will make growing some plants more difficult if they are planted nearby. Plants such as witch hazel and river birch that are sensitive to alkaline soil conditions will start to become chlorotic, or lighten and lose their green coloration, as their roots grow into the limestone base.
Look for other materials such as grade 9 gravel with fines for the base of hardscapes.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.