SUNIVERSITY OF Cooperative Extension Service
I FLORIDA Institute of Food and Agricultural Sciences
oC A Vegetable Crops Extension Publication
SIlorticultural &Scince Department P.O. 110690 Gaineavile, FL 32611 Telephone 904/392-2134
March 15, 1996
I. COMMERCIAL VEGETABLES
A. Seasonal Differences Occur in Transplants Too.
I. VEGETABLE GARDENING
A. Revised Vegetable Gardening Guide Now Available.
B. Certified Sweet Potato Plant Growers 1995 Georgia List.
Note: Anyone is free to use the information in this newsletter.
Whenever possible, please give credit to the authors. The purpose of
trade names in this publication is solely for the purpose of providing
information and does not necessarily constitute a recommendation of
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.
I. COMMERCIAL VEGETABLES
A. Seasonal Differences Occur in
Raising a crop in the spring requires
quite different cultural strategies than raising
that same crop in the fall, yet do you consider
this in your spring vs. fall transplant
production? Surely your water requirements
are different and perhaps your pesticide needs,
but what about your fertilizer inputs?
Research at the University of Florida has
shown that if you fertilize in the fall in the
same manner you fertilize in the spring, you
could be hurting your yield!
Florida vegetable transplant growers
essentially produce plants 365 days a year for
sale in- and out-of-state. Seasonal production
of vegetables dictates that transplants be
available for every production slot, be it
winter, spring, summer, or fall. We therefore
thought it would be interesting to determine if
the nutritional needs of transplants change
with the seasons.
Utilizing an ebb and flow (bottom
watering) production system we set out six
nitrogen treatments (0, 15, 30, 45, 60, 75
ppm) based on ammonium nitrate fertilizer.
Typically, fertilization began when the first
true leaf had expanded to a size of 1/4 1/2
inch. The initial soilless mix contained no
fertilizer so we could accurately determine the
total amount of fertilizer applied, which ranged
from 420 to 2100 ppm according to treatment.
All other elements, minor- and micro-
nutrients, were supplied in sufficient quantity
to provide for high quality plant growth.
Plants were watered every day with the
appropriate solution, weather permitting, and
grown for a period of six weeks. Obviously
more irrigations/fertigations were applied in
the fall than in the spring due to difference in
evaporative and transpirational demand.
We catalogued differences in seedling
growth (height, number of leaves, leaf area,
etc.) at 6 weeks when the plants were ready to
be taken to the field. A major concern for FL
growers is plant height upon arrival in the
field; they prefer a 4 inch plant. Our N
treatments yielded plant heights in the range of
2.6 8.5 inches in the fall and 2.2 6.4 inches
in the spring. Plants from all treatments were
then set in the field to determine the impact of
in-house fertilization on production. Multiple
trials in the spring and fall, at several locations
in FL, were conducted to test the seasonal
impact of seedling production on yield.
The first thing we learned from this
experiment was that fall- grown transplants
produce better with decidedly less fertilizer in
the plant house than spring-grown plants.
Higher rates of N in spring-grown transplants
favored higher field yields. However, these
same high N rates in fall-grown transplants,
suppressed first harvest yields (Figure 1).
When considering overall yield (three harvests)
the same pattern resulted; decreasing yield
with increasing N in fall grown transplants,
increasing yield with increasing N in spring
The ebb & flow system uniquely ties
irrigation to fertilization, so as you irrigate,
you fertilize. It also increases fertilization
precision because you are not "washing out"
the fertilizer with additional irrigations. It
makes sense then that in the spring, plant
transpirational demand is lower and they
require fewer irrigations. Therefore you will
have to apply higher N rates to satisfy the
plants needs. Conversely, in the fall, with high
evapotranspirational demands, smaller doses of
fertilizer per irrigation are necessary.
Additionally, lower N rates appear too more
appropriately prepare (harden?) fall-grown
transplants for the rigors of the FL fall
So when you begin to prepare for your
fall crop and consider how its needs will be
quite different from your spring crop;
remember your transplants. This is one case
where "less is better"!
Figure 1. Seasonal first harvest yields based on
plant house N rates
. .. . ..=,,,- - - --"- . . ..
---- -- .... -.. ..-.F al
5 30 45 n6 7
N Rate (ppm)
(Vavrina and Hochmuth, Vegetarian 96-03)
II. VEGETABLE GARDENING
A. Revised Vegetable Gardening
Guide Now Available.
The "Florida Vegetable Gardening
Guide," Circular SP 103, has been revised and
is now available from IFAS Publications. The
per copy price is 10 cents, as compared with
the price of the old (1992) version at $1.25 per
The new format re-captures the
pocket-size, folded style that I used for 30
years when the publication was called circular
104 and was given out to gardeners as a
"freebie." When we went to a for-sale version
in 1992, the format became a 10 x 12 inch,
glossy print manuscript that unfolded into a 20
x 24 inch poster-size planting guide. The
lettering was larger and easier to read than the
pocket-size format, yet contained no additional
information. But at $1.25 plus $2.00 handling
charge the price was too high, and since it had
to be purchased direct from Gainesville by the
gardener, the publication did not fill the bill.
Like its predecessors, the new version
(Cir 103) does not contain illustrations or
photographs -just useful no-frills information
supplied by specialists in their field (Kidder,
Short, Simone, Dunn, and Stephens). The
IFAS media group under Graddy and Woods
have done a great job somehow fitting all that
information into a presentable format. I
personally miss the big wall-chart, and
gardeners may too, but the planting guide is
still there, just more condensed.
The price certainly is right. At 10
cents per copy and eliminating the handling
charge, each of you agents should be able to
find a way to purchase several hundred copies
for distribution through your office and staff of
Master Gardeners. The information is
essentially the same as is on the latest
CDROM disk. Sure, you can print your own
from the disk, but the purchased version has a
much more presentable format, and there's no
hassle in collating, folding, and stapling.
I'm not sure that Gainesville IFAS
publications will be distributing this publication
direct to the home gardener, as we are looking
to each county Extension office as the main
distribution point. So please get your supply
now from Chic Hinton and be prepared for the
1996 spring gardening season.
(Stephens, Vegetarian 96-03)
B. Certified Sweet Potato Plant
Growers 1995 Georgia list.
Many of you agents will be asked by
gardeners and growers where to obtain sweet
potato transplants for the 1996 season. Since
the Florida Department of Agriculture can not
certify Florida growers as a source of plants,
we must rely on our neighboring states
(Georgia, Alabama, Louisiana, and
Mississippi) for plants.
The following list of growers having
plants in 1995 from Georgia farms may be
useful in advising your growers of possible
plant sources. If need be, you can contact the
Department of Agriculture in those states I
mentioned for their most current lists.
1995 GEORGIA CERTIFIED SWEET POTATO PLANT GROWERS
James R. Cook
Rt 3 Box 501
Baxley, GA 31513
PO Box 161
Surrency, GA 31563
W. R. Lightsey
296 Johnnie Thornton Road
Odum, GA 31555
Rt 1 Box 131-A
Nichols, GA 31554
Troy L. Johnson
Rt 1 Box 126
Nichols, GA 31554
206 Powers Rd.
Cordele, GA 31015
Piedmont Plant Company
PO Box 224
Albany, GA 31708
Rt 1 Box 545
Ocilla, GA 31774
PO Box 690
Leesburg, GA 31763
Rt 2 Box 1290-9
Ray City, GA 31645
PO Box 205
Omega, GA 31775
(Stephens, Vegetarian 96-03)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. S. M. Olson
Mr. J. M. Stephens
Dr. G. J. Hochmuth
Professor & Edit or
Dr. S. A. Sargent
Dr. C. S. Vavrina
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. J. M. White