Seedless Watermelon Transplant Production Guidelines: Seedless Watermelon Transplant Production Guidelines Dr. Richard L. Hassell
Coastal Research and
Charleston, South Carolina
Rhassel@clemson.edu Dr. Jonathan R. Schultheis
North Carolina State University
Raleigh, North Carolina
firstname.lastname@example.org Table of Contents: Table of Contents Introduction
Greenhouse Growing Introduction: Introduction Triploid (seedless) watermelon seed have more
exact growing requirements than diploid
Failure to provide optimum growing practices
can result in:
reduced seed germination
uneven seed germination and transplant size
weaker plants resulting in yield reduction
Slide4: Transplant production requirements are more precise with seedless watermelons than seeded watermelons. Note the reduced plant emergence and variable plant size in the transplant tray with a seedless variety (right) compared with the more complete uniform plant size in the transplant tray with a seeded variety (left) 5 days after sowing. Diploid or seeded cultivar Triploid or seedless cultivar Seed Trays: Seed Trays Choose trays that fit your particular set up and
are economically feasible for your operation
Use square cells when ever possible
Make sure cell depth is at least 2”
Remember, the smaller the cell diameter, the more attention to plant production is needed! Timely response to plant need is critical!!!
Slide6: Choose trays that fit your particular set up
and are economically feasible for your operation Slide7: Styrofoam “Speedling” grow tray - clean and re-use No. 242 cell tray
13.5” x 26.5”
1” square Slide8: Styrofoam “Speedling” grow trays – for re-use Regardless of tray type, it is critical that the tray is disinfected/
treated with chlorox Slide9: Rigid plastic tray suitable for re-use after sterilization Re-usable
13.5” x 26.5”
1.25” square Slide10: TLC #128 tray
11” x 21.5”
1.19” Square Slide11: Use square cells
when ever possible Round cells cause
root girdling Slide12: Remember, the smaller the cell diameter, the more
attention to overall plant needs must be considered!! #288 Tray - Tray dimension 11” x 21.5”
cell size -1.5” deep X .81” square Soil Mixes: Soil Mixes Choose as coarse a mix as possible for the tray chosen. (Examples are: Metro-Mix 300, Fafard Professional No 2, Pro-Mix BX)
Do not use a plug mix!
-Plug mixes are too fine.
-A fine mix makes it easy to over water
making less oxygen available to the roots Slide14: Soil mixes come
in all makes and sizes Slide15: Soil mix ingredients may vary greatly in their content Tray Preparation: Tray Preparation 1. Fill trays 24 hours before seeding.
2. Wet trays to field capacity.
3. Let trays stand 24 hours before seeding to drain excess water.
4. If warm water is not available, place trays in area where temperatures of the mix are at least 850F before seeding. Slide17: Fill trays 24 hours before seeding Slide18: Wet trays to field capacity and let stand 24 hours
before seeding to drain excess water Slide19: If warm water is not available, place trays in area
where soil mix temperature reaches at least
850F before seeding Seeding: Seeding 1. Place seeds at least one inch deep, preferably with the radicle end pointed up.
2. Cover tray with warm, moist mix or pinch the
area closed around the seed.
3. DO NOT ADD WATER TO THE MOISTENED MIX!
4. Place trays back in the warm germination room ASAP! Seeding: Seeding 5. Stacking trays OK as long as air movement
around trays is provided.
6. Remove trays after 48 hours (NOT 49!)
- seed examination not necessary.
(more than 48 hours will cause excessive hypocotyl growth).
**If seedlings have visibly started to emerge you’re too late!
Seeding: Seeding Seeders vary in shape, size, and capabilities Slide23: Place seeds at least one inch deep Radicle
up if possible
Slide24: Cover tray with warm, moist mix or pinch the
area closed around the seed Slide25: DO NOT ADD WATER TO THE
MOISTENED MIX AFTER SEEDING! Slide26: Place seeded trays back in the warm germination room
Stacking trays is permissible with air movement around them Air circulation Air circulation Slide28: Germination Chambers No single perfect design
Temperature and humidity control
Moisture is maintained by a fog system
Shelves to place the trays
Best temperature control is by hot water
pipes along baseboards Slide30: “Home-made” germination chamber Temperature Controls Insulated Sidewalls Slide31: Commercial vegetable cooler converted to germ room Heater and
controls Slide32: Uniform humidity controls is a must no
matter what the size of chamber chosen! Germination Conditions: Germination Conditions Seed Germination Takes Place In Two Stages
A. When The Root Emerges (Germ Rooms Only)
B. When The Hook Appears (Greenhouse Only)
Uniform Soil Temperature In Germ Room Must Be Maintained
A. Seedless Need 850F Germination Conditions: Germination Conditions Germination Dependent On Moisture
A. Too Much Inhibits Oxygen
B. Too Little Prevents Seed Swell
Apply A Cover Of Vermiculite, Plug Media, Sand, Perlite Slide35: Excellent seed germination after 48 hours in the germination room at 85oF Slide36: Seed germination beyond 48 hours at 85oF to 90oF Root
root hairs Slide37: Seedling emerging through soil mix Greenhouse Growing: Greenhouse Growing 1. After 48 hours, move trays to the greenhouse.
-Set night temperature at 650F.
-Cooling set to come on at 70-750F.
-Too warm setting will cause hypocotyl stretching.
3. Do not water until signs of seed emergence appear.
- Excess water will also cause hypocotyl stretching. Greenhouse: Greenhouse 4. Do not fertilize before appearance of first true leaf.
(NOT the cotyledon leaf!)
5. At first true leaf - begin fertilization with a
continuous feed of 50 ppm N or a 100 ppm
twice per month.
6. Slow growing = quality transplants!
7. Four to six weeks needed from seeding to transplant. Slide40: Remove trays from germ room after 48 hours to the greenhouse! Slide41: Greenhouse Temperatures
1. Set night temperature at 650F.
2. Cooling set to come on at 70-750F.
3.Too warm setting will cause hypocotyl stretching Slide42: DO NOT ADD WATER TO THE MOISTENED MIX
UNTIL THE SEEDS HAVE FULLY EMERGED! Slide43: If seedlings have started to emerge in the germ room you’re too late! Hypocotyl
extension Slide44: Do not water until signs of seed emergence appear! Seed coat
Too fine a mix Slide45: Excess water and high temperatures in the greenhouse
will also cause hypocotyl stretching! Slide46: Seedlings showing elongated
hypocotyl growth caused by:
2. Temperatures above
75oF. Seedlings showing short
hypocotyl growth caused by:
1. Controlled watering
2. Temperatures at 75oF
or below. Slide47: Do not fertilize before appearance of first true leaf. NOT the cotyledon leaf! First true leaf. Slide48: At first true leaf - maintain fertilization with a continuous feed of 25 ppm N
or 100 ppm twice per month Slide49: Well formed root
transplants. Slow growing = quality transplants!
Four to six weeks to quality transplants! Slide50: GOOD GROWING!