How to create a colorful flower show for autumn
Try to buy mums and asters when their flower buds are just beginning to open. The color will last longer in your garden.
Generally, mums and asters last for four to six weeks, depending on weather conditions. Season-extender mums are available later in the season and can keep color going through October and sometimes later, depending on weather.
If you are planting mums in a shady site, it is best to wait until the flowers are open before planting. If the mums are tight in bud and then planted into a shady area, the flowers may not open.
Typically, pansies do not develop much in the autumn, so it is best to buy large plants that are in full flower to install in your garden. Plant them close together for a better show.
• Plants like rhododendrons and azaleas that prefer acidic soil conditions can benefit from an application of granular sulfur to the soil in fall. If your blue hydrangeas have turned pink, sulfur applications may return the flower color to blue.
Avoid contact with the sulfur by wearing latex gloves and keeping dust out of your eyes. Apply to the soil and gently scratch in. Sulfur works slowly in the soil and repeated applications will be necessary from year to year.
• Ornamental onions (Allium) are some of the best bulbs to plant for resistance to animal browsing. They come in many varieties. Try the popular June-blooming "Globemaster" with a 10-inch pinkish-purple flower on a 2 to 3 foot stem; it lasts up to a month.
The drumstick onion (Allium sphaerocephalon) has reliable burgundy blossoms about 1-inch wide. Lily leek (Allium moly) is a small species that is 10 to 14 inches tall with yellow flowers. These are just a few of the many alliums that succeed with little effort in Midwest gardens if planted this fall.
Daffodils are also easy to grow and are resistant to animal browsing, while tulips and crocuses are readily eaten by deer and other animals.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.