Fertilization
Pot mums are "heavy feeders," especially during their initial stages of growth. A pot mum fertilization program should begin as soon as the cuttings are planted or stuck in the pot.
Constant liquid fertilization, i.e., irrigating with fertilizer solution at each watering, is recommended for pot mum production. Use a complete N-P-K fertilizer that has the majority of N in the nitrate form and contains extra micronutrients as in "Peat-Lite Special" formulations, e.g., 20-10-20, 20-5-19, 21-5-20, etc. A 200 to 300 ppm solution of N (soil root media) or 300 to 400 ppm solution of N (soilless root media) will produce high-quality pot mums. If nonleaching fertilizer delivery systems are used, such as ebb and flow, flooded floors, capillary mats, troughs, etc., the fertilization rate should be 50 to 75% lower to reduce soluble salt accumulation. Pot mum growers should have soil and/or foliar tests done at regular intervals to monitor the fertility levels of the crop.
While pot mums are "heavy feeders" for much of the crop time, it is very important to note that fertilization should be reduced or eliminated during the final 2 to 3 weeks of the crop. Work done at the University of Florida by Dr. Terril Nell has demonstrated that pot mum longevity can be increased by 7 to 14 days if fertilizer applications are terminated at disbudding, or approximately 3 weeks before marketing the crop. At the least, fertilizer should be eliminated when bud color is showing.