It's hard to beat Asters when it comes to sheer beauty, and growing Asters in containers is a cinch as long as you meet all the plant's growing conditions. What better way to brighten up a deck or patio when most flowers are winding down for the season?
Use a container with plenty of space for the roots to grow. However, avoid overly large containers, as a large amount of potting mix holds excess water that may result in root rot. It's always better to repot when the plant outgrows its container.
Be sure the container has at least one drainage hole in the bottom. Cover the hole with mesh or a paper coffee filter to prevent loss of potting mix through the hole.
Fill the container with a lightweight commercial potting mix. Never use garden soil, which compacts and doesn't allow free passage of water and nutrients. Water asters immediately after planting. Place the container where the Asters are exposed to six to eight hours of full sunlight per day.
Check the container daily during warm weather and water as needed to keep the soil moist, but never soggy. Keep in mind that Asters prefer soil a little on the dry side. A 1- to 2-inch (2.5 to 5 cm) layer of mulch will help with moisture retention.
Feed Asters monthly throughout the growing season. Alternatively, mix a small amount of slow-release fertilizer into the potting mix at planting time.
Remove spent blooms as soon as they wilt. Otherwise, the plant will go to seed and blooming will rapidly decrease.
Watch for pests, such as spider mites and aphids. Both are easily controlled by using an insecticidal soap spray. However, never spray the plants on hot days, or when the sun is directly on the plant.