Growth regulators

There are several options for growth regulators on poinsettias and the chemicals and rates utilized vary considerably due to climate and grower preferences. In the warmer temperatures of the deep south, we use higher application rates than would be used in cooler regions. In these examples, we will use a program of early sprays and a late drench if needed.

Sprays:

Prior to Oct. 1 we will use a tank mix of B-Nine and Cycocel.
High rates are 2,500 ppm B-Nine and 1,250 Cycocel
Standard rates are 1,500 ppm B-Nine and 1,250 Cycocel
Low rates are 1,000 ppm B-Nine and 1,000 Cycocel

This tank mix provides considerably greater activity in warm climates. In cooler climates, many growers use only Cycocel. B-Nine generally is not used after initiation date on poinsettias in any climate. For Florida, we use Oct. 1 as the natural day initiation date. In our examples, we may vary from these guidelines slightly depending on the variety, how vigorous the plants are and the weather.

Late drench:

The later the drench is applied the less it affects bract size. The rates used for the late drench are too high for earlier applications. Our guidelines for when the late drench can be applied in warm climates are:

1. we want the plants within one inch of final size.
2. we want one bract in color.

We will use Bonzi for the late drench and 1 ppm is the standard rate in warm climates for medium vigor varieties like Freedom Red.

In cool climates the guidelines for when to apply the late drench is:
1. the plants should be within ½ inch of final desired size.
2. there should be at least two bracts in full color. Remember the later it is applied, the safer it is. In cool climates, the standard Bonzi rate for medium vigor varieties like Freedom Red is 0.5 ppm.