Using Florel Effectively

October 10, 2002 - 09:45

Once timing, application rate and crop susceptibility are understood, Florel can be an effective tool for both controlling height and promoting branching.

With more and more new vegetative annuals being produced,
growers are finding themselves doing more pinching and cutting back to
stimulate better branching and to control growth. Many of the new vegetative
annuals are quite vigorous and designed for use in larger containers. However,
growers are also producing them for individual sale in smaller pots as well as
mixed planters. Whether you buy rooted or unrooted cuttings, the problems are
the same -- get plants to branch early to fill out the pots faster and control
the growth late.

Why Use Florel

If you have not worked a lot with Florel, you really need to
start if you plan to grow vegetative annuals profitably. Florel is an
ethylene-producing chemical that increases branching, takes off early flower
buds in many crops and acts as a growth regulator. By spraying with Florel
early, either during propagation or shortly after potting, you can get faster
branching without pinching or with less pinching. Some growers will still pinch
cuttings if the height is already too tall.

For most crops, spraying with Florel will also take off
early flowers and delay subsequent flowering for a period of time. For
geraniums, this re-blooming time can be 6-8 weeks, whereas verbena and lantana
may rebloom in 2-3 weeks. Florel will not abort flower buds on some crops, such
as mums, but will delay flowering if flower buds are not already evident.
Disbudding may be needed during propagation with crops such as New Guinea
impatiens to reduce Botrytis problems.

Florel also acts as an early growth regulator, although not
in the same manner as other chemicals such as B-Nine, Bonzi or A-Rest. And,
best of all, the cost of Florel is cheaper than other growth regulators and
definitely more cost-effective than pinching or cutting by hand.

You can use Florel in stock production, during propagation
or after potting. If you produce your own stock plants, spray Florel either in
place of pinching or around the same time to increase the number of cuttings.
Á Stop spraying Florel at least two weeks before you want to take
cuttings, so you do not have a carry-over effect into propagation, which will
delay rooting or cause more leaf-yellowing immediately after sticking.

In propagation, wait until you have some rooting and are
weaning plants off mist before using Florel. Generally, spray Florel one week
before potting to increase branching. If you want to take off early flowers in
propagation, spray earlier but at a lower rate. After potting, wait until
cuttings are rooting out into the new media before spraying with Florel. That
means Florel can be applied about 1-2 weeks after potting and can be repeated
1-2 weeks later if needed. It may take a week to show the branching effects of
Florel, so be careful about applying too frequently and getting too much
effect. Many growers like to spray hanging baskets while on the bench or ground
1-2 times before hanging. Keep good notes on re-blooming times for different
varieties in order to determine cut-off dates for using Florel.

How To Use Florel

Many growers have tried using Florel and found it doesn't
work very well for them, while other growers have had excellent results on the
same type of plants. Why? I have found growers do not know the key points for
how to best use Florel. Here's what you need to know:

pH. The water in the
spray tank after adding Florel should have a pH of 4.0-4.5. If you have high
alkalinity in your water, you may need to add a buffering agent such as pHase5
or acid to lower water pH enough. Remember, Florel itself will lower water pH
somewhat, so be careful about getting too low (pH 3.0), as you can burn plants.
Growers with very pure water may need to add a buffering agent that will
actually keep water pH from getting too low. Activity of Florel is greatly
reduced if water pH is not correct.

Concentration. Use
concentrations of 250-500 ppm for most plants. Normally, start with 500 ppm and
see what kind of reaction you get. If too strong, reduce to 250 ppm. Sensitive
crops such as any impatiens, bougainvillea and maybe some fuchsia should be
sprayed with 250 ppm to start.

Timing. Use spray
solution within 2-3 hours after making up, and do not hold overnight.

Application. Spray
like B-Nine to run-off. You need to get coverage on all leaves and stems.
Florel is not active in the soil through the Á roots. Leaves need to
stay wet with Florel for 3-4 hours to get most of the chemical into the plant.
Drying off too fast will reduce effectiveness and require a higher ppm or more
frequent spraying. Select proper time of day to do Florel spraying.

Repetition. Watch
repeated usage and determine re-blooming times. Crops such as verbena and
lantana will need more applications of Florel and will re-bloom within three
weeks, whereas geraniums may only need one application and take 6-8 weeks to

Special Circumstances.
Avoid spraying plants when under stress -- not your stress, but the stress
the plants are being grown under! Florel is a stress-exaggerator, which means
it will turn leaves yellow or cause them to drop if plants are under stress.
Make sure plants are watered properly and shade is closed before spraying. Wait
for roots to come out first on a cutting or liner just planted.

Crops That Respond to Florel

The list of crops that respond to Florel can be quite long.
I tell growers that any crop you feel needs pinching for better branching is an
automatic candidate for Florel. A lot of work has been done by Dr. Peter
Konjoian with different crops in an effort to get the label expanded. Much of
the work by growers may be off-label, but it works. Table 1, above, contains a
list of crops that respond to Florel, but by no means is this list
all-inclusive. You need to experiment with Florel on other crops and keep good

Florel works best on geraniums and other vegetative annuals
that need a pinch to branch better. You can produce fuchsia baskets with 2-3
sprays of Florel and no pinching, and get a full-looking product. Ivy geraniums
fill out hanging baskets with 1-2 sprays of Florel and may only need a pinch on
overly long laterals. Bougainvillea will branch better with Florel but may drop
leaves due to stress. Be patient, leaves will re-sprout at most of the nodes.

Florel works very well on herbs -- getting them to
branch without pinching and acting as a safe growth regulator. However, herbs
are not on the label. Some growers are trying Florel on vegetables, but you
need to watch how much drought stress you are using or your tomato plants will
turn yellow overnight.

Garden mums were one of the first crops Florel was used on
effectively, but many growers are no longer using Florel on mums. This is
primarily due to the newer varieties being better-branching with or without
pinching, and Florel has a tendency to delay flowering on some varieties even
when used near the pinch.

On poinsettias, Florel can be used five days before and
after the pinch to bring all the breaks out more uniformly. This will change
the finished shape of 'Winter Rose' so all of the blooms are held at the
top, not the staggered look that consumers seem to prefer. If you have good-quality
cuttings that take off well after potting, you may not see any benefit on
branching with Florel, just a growth regulator effect. The jury is still out
about if Florel is really needed on poinsettias.

Using Florel on stock plants and during propagation can
remove or abort early flowers on many cuttings. Be careful about rates and
timing to avoid too much stress or effect. In propagation, use 250 ppm to
remove early blooms on New Guinea impatiens, double impatiens and other crops.
Do your own trials and keep good records.

When the weather is really warm (greater than 90° F),
you may need to reduce rates to avoid creating more stress on plants. With
lower rates, you can spray weekly if needed. Poinsettias grown under high temperatures
may need rates as high as 1,000-1,200 ppm to get an effect on branching.
Remember, when using Florel, reduce your usage of other growth regulators
during that period.

Here's the bottom line on Florel: Use it on a wide range of
plants to promote branching, remember how Florel works and do your own trials.
Once you learn how to use Florel effectively, you'll wonder how you ever did
without it.

About The Author

Dr. Roger C. Styer is president of Styer's Horticultural Consulting, Inc., Batavia, Ill. He can be reached by phone at (630) 208-0542, fax at (630) 208-0966 or E-mail at

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