How To Grow Watermelons From Seed
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Growing Watermelons From Seed

Choosing The Right Type Of Watermelon To Plant In Your Garden

Choosing the right watermelon to grow can get very technical and oftentimes confusing. Like most fruits and vegetables that can simply and easily be broken down into hybrid and open-pollinated, watermelons can bend, and sometimes break the rules especially when it comes to pollination. To throw a wrench in those gears even further, watermelons also come in seedless varieties that require special circumstances to be pollinated. To keep things simple, let’s cover the differences between seedless watermelons and traditional seeded watermelons.

Seedless Watermelons

The first thing to know about seedless watermelons is that they are actually not technically seedless. No doubt you’ve cut into a watermelon and seen the small white seeds that are dispersed through the fruit. These are actually empty seed casings that are perfectly fine to eat. 
What makes a watermelon seedless is actually quite technical from a botanical standpoint. The main takeaway is that when you order a seedless watermelon variety from HOSS, you will actually be getting 2 different seed packs. One is a seed that will produce female flowers but also has male flowers present. The pollen in the male flowers is not typically enough to fertilize the plant. Because of this, we include a separate pollinizer seed that will produce the male flowers needed to guarantee successful fertilization. 

Seeded Watermelons

This is the more traditional watermelon that most people have grown to know through the years. Seeded watermelons have thick black seeds within the fruit that are fertile and, depending on the variety, can be saved and planted for another crop. Not all seeds from traditional watermelons can be saved, though. For example, seeds from F1 hybrid watermelons cannot be saved to plant again. Below are our favorite traditional watermelons seeds to grow in our area.

Growing Watermelon From Seed

Should You Direct Sow or Transplant Watermelon Seeds?

As any gardener knows, when you have a plant that can either be directly planted in the ground or transplanted, there are pros and cons to both. At HOSS, we always err on the side of starting your watermelon seeds in trays because it has proven to be a more successful strategy for our gardens and our space. We know that every garden is different but we always highly encourage starting seeds in trays when you have the option.

Benefits Of Starting Seeds In Trays

  1.  Beginning in seed trays will give you a head start on the growing season. Instead of having to wait for weather conditions to even out, your watermelon plants will have already germinated and established a root system and are ready to go into the ground immediately. This will usually result in an earlier harvest as well.
  2. More control over germination. Most seedless watermelon seeds are expensive and starting in trays will ensure that your investment is protected.
  3. Weed control. Watermelon seeds and root systems are delicate during the first phases of growing. Starting in seed trays will help keep weeds from ruining your potential crop.

Benefits Of Direct Sowing Seeds

  1. There is less cost involved with direct sowing since you don’t have to have the seed starting supplies or greenhouse.
  2. Direct sowing has less labor involved. Direct sowing allows you to simply put the seeds in the ground and let them grow as they will.

Watermelon Indoor Seed Starting Dates

Watermelon seeds should be started indoors at least 4 to 6 weeks before the last frost date for your zone. We recommend using our 162 Seed Trays for best results.

Zone 10 – December 15th
Zone 9 – January 15th
Zone 8 – February 20th
Zone 7 – March 15th
Zone 6 – April 1st
Zone 5 – April 20th

Seed Start Supply List

Indoor Growing

  • 162 Seed Tray
  • Heavy Duty Bottom Tray
  • Hanging Light Kit
  • Sungro Seed Starting Mix
  • Dramm Watering Can
  • Dr. Joe Nutri Bubble
  • Dr. Joe Growing Bubble

Outdoor Growing

  • 162 Seed Tray
  • Fogg-It Mist Nozzle
  • Sungro Seed Starting Mix
  • 100 or 150 Watt Germination Mat
  • Germination Thermostat
  • Hoss Premium 20-20-20 Fertilizer

Planting Your Watermelon Seeds

  1. Fill each cell in the trays completely with seed starting mix. Use your hands to pack the mix into each cell.
  2. Place starting tray on bottom tray and lightly water from above to generously moisten seed starting mix. Repeat 3-4 times to ensure all of the soil in the cells are moist. Water should be dripping from the bottom of the trays.
  3. Make an indentation in the center of each cell using your hands or a pencil. The indentation should be twice as deep as the diameter of the watermelon seed.
  4. Place one seed per indentation and lightly cover with the remaining seed starting mix or vermiculite. Be careful not to add too much mix over the tops of the cells, as it can delay germination.
  5. Whether you are starting indoors or outdoors, the optimal temperature for watermelon seed germination is between 75°F and 85°F, so regularly check temperatures and adjust as needed. Be sure that your trays are placed in an area with full sun or be sure that your grow light is directly above the tray, almost touching them. Move the lights up as the seedlings grow.
  6. Fertilize your watermelon seeds once a week when the plants emerge using the designated fertilizer in the supply list above.
  7. Water your seeds 2-3 times a day. Watermelons are heavy feeders and greatly rely on proper irrigation to properly form.
  8. Once the seedlings have developed a good root system, it will be time to transplant

Get A Head Start On Your Watermelons!

Watermelon Seed Tips

Make Sure To Plan Ahead

All varieties of watermelon have one thing in common: they need lots of room to grow. Contrary to popular belief, even growing smaller varieties like the Sugar Baby Watermelon needs the same amount of room to grow as the massive Jubilee Watermelon. The main thing to remember is that it isn’t the size of the fruit that you’re growing, it’s how far out the vines sprawl that you have to accommodate for. A good rule of thumb to grow watermelons is to dedicate at least 20 square feet per plant in your garden. 

Grow the Best Watermelons Ever

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