Culture Tips for Forever Kalanchoes

April 18, 2003 - 10:35

The Forever Kalanchoe series eliminates production difficulties while producing a top quality plant.

Intense breeding and selecting for the past 20 years by Dr.
Lyndon Drewlow has resulted in vastly improved kalanchoes. With the Forever
series, many of the production difficulties often associated with kalanchoes
have been eliminated. No more time and labor for pinching, no more cost of
multiple growth regulators sprays and no more guesswork in deciding which
cultivars to grow in 4- or 6-inch pots. The Forever Midi series fits 4-inch pot
cuttings and the Forever Maxi series fits 6-inch pots. style="mso-spacerun: yes">  


Transplant plugs into a well-draining medium with a pH from
5.5-6.2. Although one Forever Maxi fills a 6-inch pot, some growers still
prefer to plant three per pot. For the initial establishment of the root
system, maintain minimum night temperatures of 68º F and begin a constant
fertilization program using a rate of 150 ppm.

Between September 1 and March 21, plants need to have night
lighting to prevent premature flower bud initiation. Provide at least 10
foot-candles for two hours in the middle of the night. During the summer, grow
the plants for one week before the start of short day treatment (SDT), and
during the winter, grow for three weeks. Adjust this time to alter final plant
height. Plants will generally produce three more nodes after the start of SDT.
Use this fact to estimate the final height of the crop.

Flower Initiation

Kalanchoes are forced to flower by providing short days
— 13 hours of darkness. This treatment must last six weeks to ensure the
best flower initiation. Black cloth must be used from March 1 through October
15. Do not skip pulling black cloth, even one night, because this will delay
the crop. Simply pull 4-mil black poly over the plants, and make sure the
plastic is wide enough to drop just beyond the side of the bed. When the days
are hot and bright, pull the plastic at 7 p.m. and remove at 9 a.m. to prevent
heat 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 in
a tray during this treatment so they do not fall over while pulling the plastic
on and off. During SDT, alternate feed with clear water. Temperatures can be
dropped to 65º F.


After the completion of six weeks of SDT, kalanchoes may be
grown under natural days without concern for flower bud abortion, but give the
plants more space at this time. Four-inch pots should be on 5-inch centers and
6-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 very
temperature dependent. It can range from nine weeks in the summer to 11 weeks
in the winter. The finishing time is based on the European standard of one open
flower 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 reach
this 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 for
thrips, 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 insecticides
containing chlorpyrifos or EC formulations. Maintain good ventilation practices
to help control Botrytis and powdery mildew. Many common fungicides may be
used, but avoid using Rubigan or Karathane.

Other Cultural Tips

To grow a finished crop of kalanchoes by directly sticking
cuttings into the finished pot, increase the pre-SDT time by three weeks to
allow 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, the
SDT should last eight weeks instead of six.

To produce a fast 4-inch crop, try direct sticking unrooted
Maxi cuttings, and start SDT two weeks later. If height control of the flower
stems is necessary, especially in the summer or in the South, use 2,500 ppm
B-Nine four weeks after start of SDT. Kalanchoes respond well to inverted night
temperatures (negative DIF). Use with caution.

About The Author

Ed Mikkelson is director of research and development for Oglevee; he can be reached by phone at (714) 628-8360 ext. 115 or by E-mail at

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