Irrigation
Proper irrigation is critical to successfully produce a high-quality garden mum. Always apply enough fertilizer solution so that it soaks thoroughly down through the pot. About 10% of the water applied should run out the drainage holes in the bottom of the pot to prevent soluble salts build-up.
Garden mums should never be allowed to wilt during the early stages of growth. Wilting can restrict branching and overall growth as well as contribute to premature budding. In the later stages of growth, slight wilting can be beneficial. It can harden the plant off, control height and promote more uniform flowering.
Whenever possible, drip or tube irrigation systems should be used in place of overhead irrigation. Overhead irrigation, especially in mid- to late-summer periods, can promote the development of leaf-spotting foliar diseases such as bacterial leaf spot, Botrytis, Septoria and Alternaria. Garden mum foliage should always be dry before evening hours. Drip emitter placement should be as close to the center of the pot as possible in ensure uniform distribution of the irrigation throughout the pot.
During extremely hot periods, it is tempting to apply extra water to the pots of garden mum crops in an attempt to lower temperatures. This practice can easily lead to overwatering, root loss and chlorosis especially in peat moss-based root media. Syringing plants with a mist nozzle can reduce the heat stress without overwatering. Although difficult to apply outdoors, 25% to 30% shade can be utilized over greenhouse crops whenever possible to reduce high-temperature stress. However, keep in mind the added shade reduces heat but slows response.