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record of the Institute for Food and
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used only to trace the historic work of
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Copyright 2005, Board of Trustees, University
JUL 1 7 1979n 1 79
Ft. Pierce ARC Research Report RL-1979-7 JUL 17197%ne,- 179
PLUG-MIX SEEDING GUIDE FOR SMALL FARMS AND HOME G DENS
Norman C. Haylip 1/
Plug-mix seeding refers to the practice of precision-placing a mixture of
crop seed, water and a nutrient-enriched blend of shredded sphagnum peat moss
and horticultural vermiculite into planting sites at rates of 1/8 to 1/4 cup
of loose mixture per hill. This technique provides a uniform, favorable en-
vironment for seed germination and young seedling growth with an adequate, safe
level of fertilizer readily available to the seedlings. Plug-mix seeding has
generally produced reliable plant stands, rapid seed germination, uniform
plant growth, early maturity and increased yields compared to standard seeding
methods (1, 2, 3, 4). A tractor mounted automatic plug-mix planter is commer-
cially available for use by large-scale vegetable growers.
An inexpensive hand operated plug-mix seeder was constructed and tested
at the Agricultural Research Center, Fort Pierce. This planter can be useful
on small commercial vegetable farms, u-pick operations, home gardens and ex-
perimental plots. A detailed drawing of the unit is included on the last page
of this report for those interested in building a hand operated plug-mix
planter. Instructions on formulation and application of plug-mix follow.
Prepared peat moss-vermiculite mixes similar to "Cornell Peat-Lite",
developed by J. W. Boodley and R. Sheldrake, Jr., Cornell University are avail-
able from several commercial firms. The mixes are usually available in 4-cubic-
feet capacity plastic bags and contain approximately a 1:1 mixture of shredded
sphagnum peat moss and horticultural vermiculite with plant nutrients and
wetting agent. Mixtures to which controlled release fertilizers such as "Magamp"
7-40-6 or "Osmocote" 14-14-14 were added produced better seedling growth than
mixtures without these controlled release fertilizers. "Jiffy-Mix Plus" con-
tains "Magamp" while "Jiffy-Mix" does not. Other brand names of seeding mixes
include "Pro-Mix", "Nova-Mix", Metro-Mix", "Redi-Earth", etc. Most firms
market several types of mixes for various uses, and some are not suitable for
plug-mix seeding. Be sure the mix purchased is made with nutrient enriched
peat moss and vermiculite, and is recommended for seeding. If the mixture pur-
chased does not contain a controlled release fertilizer, "Magamp" 7-40-6 (medium
granule) can be added when incorporating seed and water (Table 1).
/ Professor, Vegetable Crops, University of Florida, IFAS, Agricultural
Research Center, Fort Pierce.
Table 1. Formulation of plug-mix, if using 1/4 cup per hill
Amount of ingredient in mix
Ingredient For 600 hills For 1800 hills
Cornell Peat-Lite Mix One bushel One 4 cu, ft. bag
*Magamp, 7-40-6 (med. granule) 1/2 Ib, 1 1/2 Ibs.
Vegetable seeds See Table 2 See Table 2
Water (to slightly moisten) One gallon Three gallons
*Check with supplier to determine if Magamp or another controlled release
fertilizer has already been added.
The Cornell Peat-Lite, Magamp (if not added by supplier), and seeds are
mixed dry for 5 minutes or more in a small tumble-type cement mixer. Mixer
drum should not be over-filled and should be tilted almost to the point of
discharging to insure complete mixing. A removable cover (such as a garbage
can lid) can be placed over the mixer opening to hold down the dust. Clean
water is added while the mixer is running. Mixing is continued for 5 minutes
or more after the water is added. Balls of mix larger than a marble, if
present, can be broken up by hand or by dumping through a coarse screen. If
a cement mixer is not available, two plastic garbage containers can be used
to make up one bushel lots. Dump soil-mix, seeds and Magamp (if needed) into
one container and pour back and forth into empty container 6 or 8 times. Then
add water and continue mixing in the same manner until moisture is uniform
Because different lots of the commercial mixes may vary in moisture con-
tent, the recommended rate of water listed in Table 1 may need to be adjusted.
It is desirable to add as much water as is possible without creating a sticking
problem in the hand plugger. Adding too much water to the mix will create
The seed-soil-water formulations can be stored for 2 or 3 days before use
(longer if kept cold). Field planting should be done before the seeds germin-
ate. One bushel of mix will plant about 600 hills, using the recommended 1/4
cup loose plug-mix per hill. Some tests have indicated little or no difference
in benefits between 1/8 cup of mix per hill and the 1/4 cup rate. If 1/8 cup
is used, the amount of seed would be twice that recommended in Table 2 for the
1/4 cup rate of application, and a hand plugger with slightly smaller diameter
pipe than the one detailed in this report would be more suitable.
Table 2 is a general guide to determine the amount of seed to be added
to a 4-cubic-feet bag of mix.
Table 2. Amount of seed required to obtain an average of about 4, 6 or 8 seeds
in each 1/4 cup of loose mix per hill .14
Amount seed (ounces) for 4 cu, ft, bag mix3/
Average Average Average
Crop seeds per ounce2/ 4 seeds/hill 6 seeds/hill 8 seeds/hill
Broccoli 9,000 0.8 1.2 1.6
Cabbage 8,500 0.9 1.4 1.8
Cauliflower 10,000 0.7 1.0 1.4
Cucumber 1,000 7.2 10.8 14.4
Eggplant 6,000 1.2 1.8 2.4
Lettuce 25,000 0*3 0.4 0.6
Okra 500 14.4 21.6 28.8
Pepper 4,500 1.6 2.4 3.2
Tomato 11,000 0.7 1.0 1.4
-/ An average of fewer than 4 seeds per hill may result in excessive skips.
For a near-perfect stand an average of 6 or more seeds per hill may be
necessary. Figures are based upon 1800 hills per 4 cu. ft. bag of mix.
2/ From "Handbook for Vegetable Growers" by James Edward Knott.
3/ For one bushel of loose mix use 1/3 the amount of seed listed.
Plug-mix seeding is suggested for smaller seeded hill crops spaced 8
inches or more apart. Examples of vegetables which may benefit from plug-mix
planting are listed in Table 2.
For more rapid seedling emergence the seed-water-soil mix should be stored
in plastic bags (use same bags mix was purchased in) in a warm location for 2 or
3 days before planting operations. If inclement weather prevents planting
after water is added to the seed-soil mix, place the mix in cold storage (about
40' F) to delay seed germination.
Two workers are required to operate the planter. One operates the plugger
and the other dumps measured amounts of mix into the side funnel of the planter
as follows: (1) lower planter in place to secure planter foot in firm contact
with bed surface, (2) raise plunger, (3) dump 1/4 cup of mix in side funnel,
(4) lower plunger to compact and force mix into plant bed.
If plastic mulch covered beds are used a hand-operated hole cutter can be
made using 2-inch diameter metal pipe with one end cut and sharpened to make a
saw-tooth edge. This tool is used to open holes in the plastic just ahead of
the hand planter. For larger plantings a tractor-drawn hole cutter wheel may
The accumulation of excess fertilizer salts at the exposed soil surface
in holes cut through plastic covered beds has resulted in serious damage to
seeds and seedlings. This problem is worse during periods of hot weather and
low rainfall when evaporation is rapid. Planting of seed without mix in holes
through plastic has resulted in poor seed germination and seedling growth
during August and September. Plug-mix has given some protection by buffering
the damaging effects of salts, but injury will occur, even with plug-mix
seeding, if the salts become too concentrated.
Studies on plastic mulch-covered beds have shown that during hot weather
with no rainfall it is necessary to apply about 1/3 cup of water into each
planting hole every 2 days until the plants are well established. The water
moves the salts down and away from the seeds and young seedlings, while main-
taining good moisture conditions. Sprayers or water wagons with nursery or
flood-jet type nozzles carefully directed over each row is an effective method
of watering. Overhead watering may not be necessary, except to keep the plugs
moist, on crops grown on beds without plastic mulch where less fertilizer is
used. However, the plug-mix seeded hills must be kept moist until the seed-
lings are well established.
1. Bryan, H. H. and N. C. Hayslip. 1973. Plug-mix seeding of tomatoes on
Rockdale soils. Homestead AREC Research Report SB73-7.
2. __ _, P. H. Everett and W. W. Deen, Jr. 1973.
Effect of "Plug-mix" seeding and mulch methods on yield and quality of
tomatoes grown on calcareous soils. Proc. Tropical Region Am. Soc. of
Hort. Sci. 17:333-345.
3. Hayslip, Norman C. 1973. Plug-mix seeding developments in Florida. Fla,
State Hort. Soc. 86:179-185.
4. _____. 1974. A "plug-mix" seeding method for field planting
tomatoes and other small-seeded hill crops. Ft, Pierce ARC Research
IFAS HAND OPERATED PLUG-MIX SEEDER DETAIL.
3 1/2" O.D.
13/8" wall; 3/4" wide
5/16" set screw
-, 16 1/2" ,
36" x 1 3/4" O.D.-1/16" wall galv. steel pipe
44" x 1 1/2" O.D.-1/8" wall al. pipe
NOTE: Adjust collar so plunger end protrudes 3/8" out of receptable.
" .. II
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