Spread a 2-inch thick layer of compost or peat over a well-drained garden bed that receives all-day sun. Cover the compost with 1 pound of 5-10-10 fertilizer per 25 square feet of bedding area. Mix these amendments into the top 6 inches of soil before planting.
Set the mums on top the soil, leaving them in their nursery pots. Arrange them into the desired layout, spacing the plants 18 to 24 inches apart. If you are growing varieties that mature to varying heights, set the taller varieties near the rear of the bed and the shorter types in the front.
Dig a planting hole for each mum at the determined location. Make the holes the same depth as the nursery pots but slightly wider so you have room to maneuver the roots into place.
Lift the mums out of their nursery pots and set them in the holes so they are at the same depth they were at in the pots. Fill the holes in with soil, firming it gently around the roots.
Water the mums immediately after planting so the soil settles and is moistened to a 6-inch depth. Mums need to be watered weekly with about 1 inch of water, which is enough to moisten the top 6 inches of the soil.