Just like chrysanthemums, kalanchoes are photoperiodic and should be treated similarly, as they are grown beginning with a long day treatment followed by short day response. Just as with chrysanthemums, the long day period and growth regulators are used to control the final plant height.
For kalanchoes, the naturally occurring critical daylength is such that any time between September 15th through March 21st, flowering is initiated without black cloth. In other words, to simulate long days and keep kalanchoes vegetative anytime between September 15th and March 21st , mum lighting must be used.
Below are a couple schedules regarding kalanchoe timing and growing. Both are for 4 to 4 ½ inch pot production.
Kalanchoe, Midi series, crop schedule for 4 ½” pots beginning AND ENDING under naturally occurring long days:
Grow Week
Week 1
Plant rooted cutting, 1ppp
Clear water irrigation
68 degrees night temp.
Week 2
Begin short day treatment
Fertilize 20-10-20, 200 ppm- alternate with clear water irrigations
65-68 degree night temp.
Week 4-10
Fertilize, 250 ppm 20-10-20. Periodic clear water irrigations are advisable. Maintain 65-68 NT. At visible bud stage, a LIGHT B-nine application may be given (1,500ppm), however, the Midis more than likely will not require it.
Week 9
The required 6.5 weeks of short days to initiate flowering has been met. Short day treatment may cease.
Week 11
Clear water to finish.
Week 12-13
Ship
Kalanchoe, Midi series, crop schedule for 4 ½” pots beginning AND ENDING under naturally occurring short days:
Grow Week
Week 1
Immediately begin long day treatment- 20 ftc for one to two hours as a night interruption (standard mum lighting is adequate)
Plant rooted cuttings, 1ppp
Clear water irrigation
68 degrees night temperature
Week 2
Fertilize 20-10-20, 150 ppm
65-68 night temp.
Week 2.5-3
Discontinue long day treatment (short day treatment begins)
Alternate clear water and 200 ppm, 20-10-20
Week 4-10
Fertilize, 250 ppm, 20-10-20. Periodic clear water irrigations are advisable.
Maintain 65-68 NT
At visible bud stage, a LIGHT B-nine application may be given (1,500 ppm), however, the Midis more than likely will not require it.
Week 12
clear water to finish
Week 13-14
Ship
Notes:
Just like poinsettias and chrysanthemums, kalanchoes have response times associated with them. These response times are based upon typical greenhouse temperatures and can be shifted +/- several days, perhaps more, by merely altering finishing temperatures (not unlike poinsettias or chrysanthemums). If a particular crop seems late, higher finishing temperatures may be implemented. If the crop appears early, lower finishing temperatures may be implemented. Experience plays an integral role in accurately hitting a ship date. Because kalanchoes hold VERY well on the bench, err on the side of a slightly early crop
Night temperatures above 80 degrees during flower initiation may result in heat delay.
Under short day treatment, kalanchoes are very sensitive to light pollution. For this reason, growers should carefully set up their black cloth structures or ensure that there is no outside light entering the greenhouse. Additionally, kalanchoes are sensitive to inconsistent black cloth treatment (more so than mums, by the way). Missed nights will result in a delayed crop.
In the second schedule, one additional week of long days is given. This is to account for the naturally occurring lower light levels associated with the fall through winter months.
Please note: The above schedules are do not account for crops that span a period of time where naturally occurring short days switches to naturally occurring long days, or vice versa. Long or short day treatments may have to be implemented as required due to these changes.