Plant garden mums in the spring. This gives them the entire summer to grow and become established, increasing their odds of surviving the cold the following winter.
Find a place in your yard where mums will get plenty of sunshine, but allow them time in the dark at night. Don't plant them where yard lights or outside house lights will interfere with natural rhythms of light and dark, or they will have trouble growing and blooming properly.
Feed your mums the nutrients they need to be robustly productive. Choose any standard complete garden fertilizer, such as a 5-10-5 or 5-10-10, and apply it according to the directions by the manufacturer. Stop fertilizing once you notice buds developing.
Water your mums daily. In the hottest part of summer, water them two or more times a day, but don't let them stand in water. The soil should be well drained.
Protect your mums from pests and diseases. Fungi such as powdery mildew and rust plague some mums. Pests that damage or kill mums include aphids, mites and nematodes. Apply a fungicide, fumigant and/or insecticide as needed to control them.