Culture Tips for Forever Kalanchoes
Intense breeding and selecting for the past 20 years by Dr.Lyndon Drewlow has resulted in vastly improved kalanchoes. With the Foreverseries, many of the production difficulties often associated with kalanchoeshave been eliminated. No more time and labor for pinching, no more cost ofmultiple growth regulators sprays and no more guesswork in deciding whichcultivars to grow in 4- or 6-inch pots. The Forever Midi series fits 4-inch potcuttings and the Forever Maxi series fits 6-inch pots.
Transplant plugs into a well-draining medium with a pH from5.5-6.2. Although one Forever Maxi fills a 6-inch pot, some growers stillprefer to plant three per pot. For the initial establishment of the rootsystem, maintain minimum night temperatures of 68º F and begin a constantfertilization program using a rate of 150 ppm.
Between September 1 and March 21, plants need to have nightlighting to prevent premature flower bud initiation. Provide at least 10foot-candles for two hours in the middle of the night. During the summer, growthe plants for one week before the start of short day treatment (SDT), andduring the winter, grow for three weeks. Adjust this time to alter final plantheight. Plants will generally produce three more nodes after the start of SDT.Use this fact to estimate the final height of the crop.
Kalanchoes are forced to flower by providing short days— 13 hours of darkness. This treatment must last six weeks to ensure thebest flower initiation. Black cloth must be used from March 1 through October15. Do not skip pulling black cloth, even one night, because this will delaythe crop. Simply pull 4-mil black poly over the plants, and make sure theplastic is wide enough to drop just beyond the side of the bed. When the daysare hot and bright, pull the plastic at 7 p.m. and remove at 9 a.m. to preventheat delay. Since there is no need to black cloth after the end of six weeks,there will be no damage to the flower buds. Also, keep the plants pot tight ina tray during this treatment so they do not fall over while pulling the plasticon and off. During SDT, alternate feed with clear water. Temperatures can bedropped to 65º F.
After the completion of six weeks of SDT, kalanchoes may begrown under natural days without concern for flower bud abortion, but give theplants more space at this time. Four-inch pots should be on 5-inch centers and6-inch pots on 9-inch centers. Return to a constant feed program of 150 ppm,except use clear water for the last two weeks of the crop.
The time to finish the crop from the start of SDT is verytemperature dependent. It can range from nine weeks in the summer to 11 weeksin the winter. The finishing time is based on the European standard of one openflower on the plant. This is the ideal time to sell the crop; however, U.S.buyers often want one-third of the flowers open. Add about two weeks to reachthis stage.
Pests and Diseases
Aphids are the most predominant insect pest on kalanchoes,while mealybugs can also be a problem. Kalanchoes are not the first choice forthrips, but thrips will feed on them, and they can become infected with INSV.Scout for all of these pests and treat accordingly, but do not use insecticidescontaining chlorpyrifos or EC formulations. Maintain good ventilation practicesto help control Botrytis and powdery mildew. Many common fungicides may beused, but avoid using Rubigan or Karathane.
Other Cultural Tips
To grow a finished crop of kalanchoes by directly stickingcuttings into the finished pot, increase the pre-SDT time by three weeks toallow for the rooting of the cutting.
To produce a very small finished plant (as small as 1-inch),direct stick a cutting in the finished container and immediately start SDT.Since a cutting does not perceive short day until it has initiated roots, theSDT should last eight weeks instead of six.
To produce a fast 4-inch crop, try direct sticking unrootedMaxi cuttings, and start SDT two weeks later. If height control of the flowerstems is necessary, especially in the summer or in the South, use 2,500 ppmB-Nine four weeks after start of SDT. Kalanchoes respond well to inverted nighttemperatures (negative DIF). Use with caution.