Buy mums with flower buds that are just about to open
Autumn is a good time to core aerate your lawn to reduce soil compaction and thatch if you did not aerate in spring. Core aerating once a year is enough for most residential lawns with normal use. Very high-use lawns benefit from being aerated twice a year. It also provides an opportunity for overseeding to help improve and thicken up your lawn. Keep the seed moist for good germination. Core aerating is best done when the ground is somewhat moist. Leave the soil/grass plugs on the lawn to break up and filter back down to the soil level. The plugs typically break down in seven to 14 days. Mark sprinkler heads and light fixtures in the lawn so they will not be damaged.
• Try to buy mums and asters that are available now in most garden centers 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 will be 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 season, so it is best to buy large plants that are in full flower to install in your garden. Also, plant them close together for a better show.
• It is time to order spring-flowering bulbs–ordering early in the season helps ensure availability of the varieties you want. Choose a site with well-drained soil. Any area in the garden that remains wet for long periods–or has standing water for any length of time–is unsuitable for bulbs. They prefer moisture in spring and fall and drought in summer. Most prefer full sun. When planted beneath a high-branching tree, spring bulbs will often flower before the tree leafs out and will have only light shade to contend with. Summer snowflake (Leucojum aestivum) does have some tolerance for moist conditions.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.