Prepare to take action with first frost

The average first frost at the Chicago Botanic Garden is Oct. 15, though it is typically later in Chicago. Tender plants can be protected from light freezes by covering them with sheets, plastic or boxes.

When night temperatures begin dropping below 40 degrees Fahrenheit, bring in any tropical plants you are keeping outside. A gradual decline in temperatures over a period of time is best, as the plants acclimate to the cooling weather. You may want to move tropical plants in for a night if there has been a long spell of warm weather and a sudden dramatic drop in temperature is predicted.

• Warm fall days are great for installing holiday lights, though most people do not think about installing lights until after Thanksgiving. It is much easier to wrap branches with strings of lights on warm days in mid- to late October than on cold days in late November or early December.

Use LED lights to save on power and be able to use more strings on a circuit. 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 have a blue cast to them.

Wrap branches of your trees with strings of lights to accent the tree's form. Chicago Botanic Garden staff starts installing strings of lights in early October.

You may be able to leave lights on your trees for a couple years to save time. As the tree grows, the lights will tighten, so they will need to be reinstalled. Be sure to use power cords that are rated for outdoor use.

• Warm, dry weather has continued, so it is important to continue providing supplemental water to any plants installed over the last two years. Plants installed three years ago and any older plants showing drought stress also benefit from additional watering now if you have not already done so.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.