Photoperiodic Lighting
Pot mums generally require night lighting during the initial portion of their growing schedule. This is the "long-day" portion of a pot mum crop. Long days are used to maintain vegetative growth and to help determine overall finished plant size. The number of long days required can vary by cultivar and pot size. Knowledgeable sales representatives, published schedules and suppliers can provide this information. Long days begin immediately upon planting.
In order to provide long-day conditions for pot mums, it is necessary to provide a minimum of 10 footcandles of light at plant level during the middle of the night. Do not permit more than 7 hours of continuous darkness to occur prior to or after the lighting period. The recommended duration of lighting each night varies according to the time of year as shown in the chart below:
| MONTH |
HOURS
PER NIGHT |
MONTH |
HOURS
PER NIGHT |
MONTH |
HOURS
PER NIGHT |
| January |
4 |
May |
3 |
September |
3 |
| February |
4 |
June |
2 |
October |
4 |
| March |
4 |
July |
2 |
November |
4 |
| April |
3 |
August |
3 |
December |
4 |
Night lighting has traditionally been accomplished through the use of incandescent lights providing a minimum of 10 footcandles at plant level. To provide a minimum of 10 footcandles, 11/4 watts of light for each square foot of area, including walks, is required. If there is any doubt, use a light meter. Sixty-watt incandescent light bulbs (with reflectors) can be placed 4 feet apart and 2 to 3 feet above the plants on a 48"-wide bench to achieve 10 footcandles.