Growing or placing potted mums (Dendranthema x grandiflora) outdoors adds a seasonal flower display to your landscape, and planting the mums in the garden after they flower allows some plants to continue growing. Potted mums are hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10a. The container label sometimes states whether a potted mum is suitable for planting outdoors.
Growing Mums Outdoors
Potted mums grow well in partially shaded and sunny spots, and in freely draining, organically rich soil. In warm climates, the plants need protection from hot afternoon sun, so plant them where they'll have shade in the heat of the day. The best time for planting potted mums outside is spring.
To provide organic matter in sandy, dry or poor soil, spread a layer of compost or peat 3 to 4 inches deep, and mix it into the soil to a depth of 6 inches before planting.
Remove the potted mum from its container, and place it in the hole.
Scoop the dug soil around the root ball until the hole is full.
Firm the soil gently with your hands.
Water the plant until the soil is moist to the depth of its root ball.
Deep, infrequent watering provides the best growth in potted mums. Water the plants when the soil is dry to a depth of 1 to 2 inches. In sandy soil, the plants may need water every two or three days, but in heavy soil they need water less frequently.
Drought causes potted mums to lose their lower leaves and develop tough, woody stems. Overwatering causes yellow leaves that blacken and fall.
Planting Faded Mums Outdoors
You can plant potted mums outdoors after they flower; this gives some plants a new lease on life, providing they receive protection from winter temperatures.
Plant faded potted mums in a sunny site sheltered from strong winds. Not all potted mums survive winter outdoors, but planting them in a warm site increases the chances of success because their root systems can develop before winter weather arrives.
Prune faded flowers where they join the rest of the plant, and prune halfway down each stem, just above a leaf. Water the plants so that the soil is moist to the depth of the root balls. Water the plants as needed while they're actively growing.
Sterilize pruning shear blades by wiping them with a cloth that was soaked in rubbing alcohol, before and after pruning potted mums.
Mulches protect potted mums from frost and heavy rain, which can cause rotting. Spread a layer of leaf mold, garden compost, shredded bark or other organic matter 4 to 5 inches deep around potted mum stems before the first local average frost date.
Don't cut potted mums down in the fall. The faded stems help protect the roots from frost.