UNIVERSITY OF Cooperative Extension Service
FLORIDA Institute of Food and Agricultural Sciences
A Vegetable Crops Extension Publication
Horticultural Scienea Department P.O. 110690 Gaineville, FL 32611 Telephotn 904/392-2134
March 17, 1997
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
IIL COMMERCIAL VEGETABLES
A. Evaluation of Asparagus Production in Florida.
B. Role of Preplant Fertilizer with Drip Fertigation.
IL. VEGETABLE GARDENING
SA. Growing Garden Tomatoes in Cans.
SNote: Anyone is free to use the information in this newsletter. Whenever
S 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 product.
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.
f'V'W ADTnr rvTCl'r TflTM TIAfTDV TM AftiT AnTT TITD "c uIlC cmmrtrratfc CTATVcnrI nn rIMA TAC rTTnflDrcrrv nE cT nirIA
I NOTES OF INTEREST
A. Vegetable Crops Calendar.
May 14, 1997. 42nd Vegetable Field
Day, 8:15 AM-1:30 PM. Gulf Coast Research
and Education Center, 5007 60' St. East,
Bradenton. Contact Dr. Don Maynard.
H. COMMERCIAL VEGETABLES
A. Evaluation of Asparagus
Production in Florida.
Asparagus (Asparagus officinalis L.)
is native to the Mediterranean area, and has
been used as an herb and vegetable for at least
2000 years. The plant is a dioecious,
herbaceous perennial widely grown in
temperate areas of the world where distinct
growing and dormant seasons occur. The
dormant season may be related to low
temperature or low moisture availability.
More recently, production schemes for tropical
climates have been developed.
Asparagus plantings are established
directly from seed, from containerized
transplants, or from 1 year old field-grown
crowns. After a 1 to 2 year establishment
period, asparagus for market is harvested for
about 2 months, fern growth for replenishment
of crown carbohydrates occurs for several
months, and a dormant period lasts for several
months. There are many variations on this
general theme depending on the production
regime being employed and local climatic
California, Washington, and Michigan
are the leading asparagus producing states in
the United States. New Jersey, Illinois, and
several other states produce asparagus for
local markets. As far as can be ascertained,
there is no recent published report on
asparagus production in Florida. Tests (up to
275 acres in size) on the organic soils around
Lake Okeechobee were reported in Bul. 36,
"Asparagus growing in Florida", Florida
Department of Agriculture, Sept. 1930.
An asparagus planting was established
from one-year old crowns at the University of
Florida's Gulf Coast Research and Education
Center, Bradenton in February 1991 and
terminated in April 1996. 'Apollo', 'UC 157
F,', and 'Viola' (California Asparagus Seed
and Transplants, Inc., Davis, CA) and 'Syn 4-
362M' (Jersey General), 'Syn 4-51' (Jersey
Prince), 'Syn 4-53' (Greenwich), 'Syn 4-56'
(Jersey Giant), and 'Syn 4-MD10' (Jersey
King) (Nourse Farms, Inc., South Deerfield,
MA) were planted in raised beds of EauGallie
fine sand (sandy, silicaceous, hypothermic,
Alfic Haplaquods). The Syn lines were
derived from the varieties shown in
parenthesis, but were not all male hybrids.
Soil samples were obtained from the
experimental area before fertilization and
annually thereafter, and analyzed by the
University of Florida Extension Soil Testing
Laboratory. Soil pH fell to 6.2 in 1996, but
ranged between 7.1 and 7.8 in other years.
Phosphorus concentration ranged between 22
ppm (medium) and 40 ppm (high) except for
1994 when it fell to 10 ppm (low).
Magnesium concentration ranged from 56 ppm
(high) to 92 ppm (high) throughout. Dry
fertilizer application was made preplant at 50-
87-83 lb/acre N-P-K and in 1994 at 0-76-0
lb/acre N-P-K. Nitrogen and potassium were
applied weekly by fertigation.
Peaked beds, 12 inches high on five-
foot centers, were prepared with hiller discs.
A six-inch deep trench was made in the bed to
accommodate the crowns which were spaced
on 18-inch centers in the row. The trench was
backfilled to about 3 inches. Back- filling was
completed later when spears had emerged and
were established. Each 15-plant plot was
replicated three times and arranged in a
randomized complete-block design. Netafim
Typhoon drip irrigation tubing (20 mil, 24-inch
emitter spacing) was installed in the bed center
after the final backfilling. Anchoring of the
tubing with wire wickets was necessary
because of the peaked bed shape. The tubing
was operated at 10 psi and delivered 0.38
gallons per hour per emitter or 0.32 gallons
per minute per 100 linear feet. The irrigation
system was operated on an "as needed" basis
to supplement rainfall. Tensiometers placed 6
inches deep in the bed center were used to
monitor soil moisture. The irrigation system
was timed to deliver 30 and 45 minutes of
water per cycle (equivalent to 0.03 and 0.05
inches per cycle), and a single daily cycle was
typically used. By mid-April the 45 minute
daily cycle was used.
Fern growth was rampant. It was
mowed and removed in late December 1991
and each December thereafter. The beds were
renovated with disc hillers in 1991 but not in
subsequent years because of the threat of
crown damage. Paraquat was applied for
weed management prior to spear emergence.
Nine-inch long spears were harvested
for 2 weeks in late January 1992. In
subsequent years, harvest commenced from
mid-January to late-February depending on the
weather and continued for six to eight weeks.
Spears were graded for size according to
United States Standards for Grades of Fresh
Asparagus as very small, < 5/16 inch; small,
5/16 to < 8/16 inch; medium, 8/16 to < 11/16
inch; large, 11/16 to < 14/16 inch; and very
large, > 14/16 inch in diameter measured one
inch from the butt, and otherwise conforming
to the standards for U.S. No. 1.
asparagi Saccardo) c
but was readily m
applications of maneb.
af spot (Cercospera
occurred each summer,
managed by periodic
In 1992, with a 2-week harvest
interval, 'UC 157' F, produced the highest
yields in all spear size categories. In 1993,
with a 6-week harvest period, 'UC 157' F1
again produced the highest yields. There was
no yield difference among the entries in 1994
for an 8-week harvest cycle. In 1995, 'Syn 4-
56' and 'Syn 4-MD10' yields were greater than
those of other entries in a 7-week harvest
interval. The asparagus was harvested for 7
weeks in 1996, but there were no yield
differences among the entries. For the 5-year
totals, 'Syn 4-362M' and 'Syn 4-51' yields
were lower than those of the highest yielding
entries, 'Syn 4-MD10' and 'Syn 4-56'. Yields
of the other entries did not differ from the high
and low yields. Highest yields overall were
obtained in 1994 with a slight decrease in 1995
and a drastic decrease in 1996 suggesting that
the longevity of asparagus plantings in Florida
may be considerably shorter than those in
principal producing areas.
Average annual yields per acre in this
trial ranged from 841 lbs/acre for 'Syn 4-51' to
1530 lb/acre for 'Syn 4-MD10'. This is far
below the annual average yields of 3633
lb/acre produced in Washington, 3000 lb/acre
produced in California, and 2433 lb/ acre
produced in New Jersey.
Greatest average spear weight and the
highest proportion of very large and large
spears were produced by the purple-colored
variety 'Viola' for most of the experimental
period. Spear weight was greatest in 1993,
the second harvest season, and declined each
year thereafter. This is another indication that
asparagus planting longevity in Florida is
Even though 'Viola' had the largest
spears in this trial, only 2% were very large
and 8% were large while 33% were medium,
31% small, and 26% very small. This can be
contrasted with 'Syn 4-51' which had 61% of
its spears in the very small size category.
Based on the results of this trial, it
does not appear that asparagus is a viable
economic alternative crop for the southern
peninsula of Florida. However, new varieties
are being developed constantly so there may
be some that are suitable for production here
in the future.
(Maynard, Vegetarian 97-03)
B. Role ofPreplant Fertilizer With
Injecting fertilizer into the drip
irrigation system is providing several benefits
for nutrient management on the vegetable
farm. Fertigation is particularly beneficial for
the management of the nutrients such as
nitrogen and potassium which are mobile in
many light-textured soils. One often-asked
question regarding fertigation programs is
"What proportion of the total fertilizer amount
should be placed in the soil as a preplant
application versus the amount to inject?"
Our research and experience here in
Florida shows that the answer depends on at
least three issues. One issue is the nutrient in
question and the second issue relates to the
native fertility of the soil being used. The third
and probably the largest issue is the relative
water management capability with the drip
irrigation system. We can look at these three
Plant nutrients. Certain nutrients are
better managed with fertigation the soil
mobile elements such as N and K. However,
a nutrient such as phosphorus (P) should be
placed in the soil when the bed is formed and
the mulch applied. Phosphorus does not leach
from the vast majority of soils so placing all P
in the soil does not place it at risk to leaching
from an untimely over irrigation event. In
addition, P can precipitate with calcium (Ca) in
irrigation water containing large amounts of
Ca as is the case here in Florida with our water
pumped from limestone aquifers.
Most recommendations call for all P to
be applied preplant but, if an injection of P is
required, precautions should be taken to insure
that P remains solublized during the injection.
This is usually accomplished by acidification of
the injected P solution or by injecting
Soil type and fertility status. On very
sandy soils, the placement of 20 to 25% of the
total N and K in the bed with the P has been
shown to lead to higher-yielding crops. This
small amount of N and K helps the young
plants establish a large root system and
provides nutrition to the crop during the early
growth stages when large amounts of drip-
applied water are not needed. The advantage
of this preplant N and K is particularly evident
in rainy crop establishment seasons, such as
the fall in Florida.
Water management. Preplant
application of nutrients during bedding implies
a certain amount of risk of the preplant
nutrients to leaching from either heavy rainfall
or an inadvertent over irrigation. Therefore,
each grower should evaluate the nutrient
leaching risk in light of the potential for
leaching. The coarser textured the soil is, then
the more critical this evaluation becomes.
Water management is the key to optimal
nutrient management, especially with drip
irrigation. Maximize water application
efficiency and management and you can do
just about anything with the nutrient
application program. The nutrients will stay in
the root zone until used by the plant.
Summary. There is no universal recipe
for nutrient management with a drip irrigation
system. The specific plant nutrients required
by the crop, the native soil fertility status, and
the water management in the field are key
issues that need addressing. What works best
with some vegetable growers and in some
farming situations may not work for another.
The considerations presented here should help
with an analysis of the role preplant fertilizer
application may play in your drip-irrigated
(Hochmuth, Vegetarian 97-03)
II. VEGETABLE GARDENING
A. Growing Garden Tomatoes in
Growing good, big, juicy, red-ripe
tomatoes will be the aim of many thousands of
Florida home gardeners this spring season. To
grow tomatoes, with space limitations, one
should consider "canning" tomatoes that is,
growing them in cans.
Tomatoes grown in cans and other
containers produce well, and make attractive
plants. To enhance the landscape, cans may be
placed at strategic locations around the
exterior of the home.
Furthermore, tomato fruits produced in
this manner are just as tasty and nutritious as
those grown in the ground.
This article describes a method of "can
culture" used successfully in a home garden in
central Florida. The principles used were
sound, and the results were outstanding.
There is every reason to believe that the
system will work just as well for you.
Containers: The gardener used 5-gallon
square cooking oil cans. Anything similar,
such as paint buckets, bushel baskets or plastic
garbage cans may be used. Do not use smaller
containers unless varieties suitable for hanging
baskets are planted.
Location: A four-foot wide strip of
black polyethylene was laid out on the ground.
It was long enough to accommodate about 24
cans. The cans were placed on the mulch in
full sunlight. Containers may be placed
wherever they might be most attractive. Since
the containers have their own soil, they can be
placed on hard surfaces such as concrete
patios or wooden decks (even boat decks).
Soil: Sawdust was used as a soil-
substitute. It is important to use well-rotted,
old sawdust for best results. Although this
gardener did not put anything else in the
sawdust at the time it was placed into the cans,
it is advisable to mix about a half cup of
dolomite in each can to provide sufficient
calcium for preventing blossom-end rot.
Varieties: Plants were set directly into
the sawdust. The varieties used were
'Floradel,' 'Walter,' 'Big Boy,' and
'Stakeless.' Best production was obtained
from 'Walter' and 'Floradel' and least from
'Stakeless.' 'Big Boy' was only fair. Other
varieties suggested for use are 'Floramerica, ',
'Better Boy,' and 'Solar-Set!' Also, the small-
fruiting varieties such as 'Summer Cherry' do
well in can culture. The latter will also permit
growing into the warm summer months.
Fertilizer and Watering: A fertilizer
solution was prepared and applied daily to
each can. The fertilizer solution was mixed in
a five gallon container. The gardener mixed
two tablespoonfuls of high analysis soluble
fertilizer (Nutri-sol) into five gallons of water.
One gallon of this solution was poured into
each tomato can once each day. At the end of
each week, the fertilizer was omitted and,
instead, each container of sawdust was given
a thorough wetting with the garden hose. The
purpose was to wash out accumulated salts
from the fertilizer, since soluble salt buildup
can cause root injury.
Alternatives to the methods of
fertilizing used might be mixing a slow-release
fertilizer into the sawdust before planting; or
twice weekly light applications of dry common
fertilizer such as 8-8-8 to the sawdust surface
followed by watering in.
Staking and Supporting: All varieties
should be supported so that they are made to
grow in an upright position. Regular methods
of supporting such as staking and string-
trellising may be used. Caging with wire is
Further care: The usual care and
attention was provided as the plants grew.
Some pruning was done to remove unwanted
suckers. Pesticides, as needed, were sprayed
onto the plants. Weeds were not a problem,
since the black plastic kept the weeds away
from the area around the cans, and the
sawdust contained no weed seeds.
(Stephens, Vegetarian 97-03)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. S. M. Olson
Dr. G. J. Hochmuth
Dr. S. A. Sargent
Dr. C. S. Vavrina
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. J. M. White