Several calls have been coming in concerning poinsettias - here
are a few growing tips as you finish out your crop.
Watering / Fertilizer:
1. Water as needed with water soluble fertilizer 20-10-20 @ 250 ppm until Oct 15th
2. Water as needed with water soluble fertilizer 15-0-15 @ 200 ppm from Oct 15 until finish date.
3. Water with plain water every 5th watering.
4. Over-watering will result in plant decay, root rot and disease problems.
5. Letting plants dry up will result in loss of finish foliage and possible crop loss.
Light:Poinsettias need full sunlight. The shade cloth should be removed by
now. If you have other plants that need
shade, pull the shade cloth back and allow full sun for your poinsettias and shade
for the other plants.
Heat: Night Temperature should not be below 60 degrees, Day Temperature should not be below 70 degrees.
Space on Bench: space plants according to size to avoid stretching
6" pot space 12" on center, 8" pot space 18" on center, 10" pots space 24" on center
Height control: Most schools grow Freedom poinsettia varieties and you may be able to finish these plants without growth retardants. If you are pushing these plants with fertilizer, heat, and plenty of light, they would be helped by an application of growth retardant. If you are growing other varieties, a growth retardant may be necessary to keep the plants from stretching. This is especially true for the schools in the Central and South Regions that are growing the white variety, Snowcap. This is an aggressive variety and must have a retardant to keep them within a desirable height. If you plan to use a regulator, apply it before October 15 or the bracts size will be reduced. Here are some growth regulators and rates. Remember that plants should be well water and the leaves allowed to dry before you spray.
Cycocel - Use 1 ounce per gallon (1000 ppm) of water on Freedom varieties and 1 1/2 (1500 ppm) ounces per gallon on taller varieties. Spray on a cloudy day or in late afternoon.
B-Nine - Use 3 tablespoons per gallon (3,700 ppm) of water. Spray on a cloudy day or in late afternoon.
B-Nine / Cycocel mix - This is the most effective way of controlling height. Use 2 tablespoons of B-Nine and 1 1/2 ounces of Cycocel mixed into one gallon of water. Spray on a cloudy day or in late afternoon.
Insecticides: Whiteflies are a serious pest of poinsettias. It is almost
impossible to control whiteflies without Marathon. Application of Marathon
should take place about 3 weeks after planting. The insecticide is a
systemic and a good root system is necessary for the plant to take up the
Marathon. If you see whiteflies before the Marathon is applied, use
Orthene, soap, or Sanmite to kill the early insects. If you have other
plants in the greenhouse, make sure they aren't the source of your
whiteflies (lantana is often a host for whitefly).
Fungicides: Apply late October soil drench application, use as a preventative to avoid plant disease.
Clearys 3335 or Banrot