While most ornamental growers view garden mums as a fall commodity, the possibility of enhancing spring and summer sales should not be overlooked, according to plant experts with University of Massachusetts (UMass) Extension.
In the spring, garden mums can be sold as green plants along with perennial crops, or as flowering plants where they can be planted by the consumer to flower again in the fall. Garden mums can also be shaded and grown for markets in July and August.
UMass offers an online guide on best production practices for mums, starting right at the beginning with handling rooted cuttings. It is best to plant the rooted mum cuttings immediately. If necessary, they may be stored for two to three days in a cooler at 33°F to 40°F. Before placing the plants in the cooler, inspect them for damage from heat or cold, broken cuttings, or wilted cuttings. Be certain that the rooting medium is slightly damp.
Any growth medium that is well-drained and aerated may be used for planting. The mix must be free of insects, disease organisms, and weeds. The pH for a soil-based medium should be 6.3 to 6.7 and 5.8 to 6.2 for a soilless medium. Have your mix tested prior to potting.
Most garden mums are grown with one rooted cutting planted per 8-inch mum pan or similar-sized container. Larger 12-inch and 20-inch are used as novelty plants. The potting mix should be moist but not sopping wet. Plant cuttings at the same level cuttings were in the cell pack. Irrigate the medium after planting at least two times, and three if necessary, until the growth medium is wet. The final initial irrigation should contain 200 ppm each of nitrogen and potassium using 20-10-20. Some growers prefer to initially plant the cuttings in small containers and transplant them later into their final larger containers when more space is available.
Garden mums initiate flower buds easily and develop rapidly, especially if plants are stressed in any way. If terminal flower buds are observed when cuttings arrive, they should perform satisfactorily. When cuttings with terminal flower buds are planted, they should be pinched hard (allow four to five leaves to remain) when they are turgid. This will force out lower breaks, which tend to be more vegetative. If both terminal and lateral buds have developed when cuttings arrive, it is best not to plant them, as they most likely will not perform well.
For more tips, including fertilization, growth management, and crop protection, go to https://ag.umass.edu/greenhouse-floriculture/fact-sheets/growing-garden-mums-for-fall-sales.