Asters and garden Mums
You can plant asters and garden mums in a container or in the garden. Be sure to plant them in a sunny location where they will get at least a half day of sun. Plant them in soil with good drainage. Soil drainage can be improved by adding compost or peat. Plant about 18 to 24 inches apart and to the same depth as the pot it originally came in.
Watering and Fertilizing
Water well after planting. Fertilize in the spring/summer growing season with a general fertilizer. Do not fertilize while in bloom.
You will need to pinch the plant to keep it compact and bushy. Asters should be pinched when the new growth is about 3 to 5 inches long. Use your thumb and index finger to remove half of the new growth on each new shoot. Do not continue pinching after mid-July.
Pinching is necessary to develop compact, bushy garden mums. It is very important to pinch back new growth in the spring. Wait until the new growth is about 4 to 6 inches tall and then pinch half of the growth from every shoot. Continue pinching new growth until mid-July.
Staking may be necessary for certain tall varieties of asters but other varieties can generally be controlled by pinching.
You do not have to cut back old flowers or stems until the spring. A light mulch can be applied around the plant after the ground freezes. In spring the old stems and mulch can be removed with a rake.
After they are done blooming, you can also overwinter your asters and garden mums indoors. Set them in a spot where the plants will get bright, indirect sunlight for half the day. Avoid placing them near heater vents or near appliances which give off heat. Do not fertilize. Water thoroughly but do not allow them to stand in water for more than a few hours.
Plant outside once the danger of frost has passed and enjoy the plant when it flowers again in the fall.
Asters and mums can be planted in landscape settings where their colours will complement the shrubs and evergreens around them.
Bees and other insects are attracted to asters, so keep this in mind if you are planning to plant them near a patio or other social-gathering place.