The watermelon growing process starts similarly for the gardener and the commercial grower. We both start by choosing which variety to grow based on our own preferences or the markets preferences.
The different types & varieties of watermelon are many. They come in different sizes – personal <5 lbs. , icebox 5-10 lbs., and picnic >10 lbs. There are watermelon varieties that have pink, yellow, orange, and white flesh. There are seeded and seedless varieties.
Commercial growers growing seedless varieties will almost always start them indoors because of the high cost of seed for seedless varieties they want to ensure good germination rates and little wasted seed. So, that’s where this article starts, planting watermelon seeds in starter pots.
Plant Watermelon Seeds in a Starter Tray
Use a pencil to make holes 1/4″-1/2″ deep in the soil mix in each of the starter pots. Place the watermelon seeds in the holes, cover with dirt and pat down gently. Water the starter tray from the bottom.
To water a starter tray from the bottom fill it with a 1/4″ of water. Check the top of the soil in the starter pots by feeling for wetness. In about 30 minutes the top of the soil in the starter pots should be moist and you can dump out any remaining water in the tray.
Check out cow pots as starter pots. As featured on “Dirty Jobs”, cow pots are environmentally friendly and made by a third generation dairy farmer.
Soaking Watermelon Seeds in Water
It is not necessary to soak watermelon seeds in water. The point of soaking the seeds in water is to increase germination rates and/or speed up germination.
I very rarely soak seeds before planting them. If you have viable seeds they will sprout fine and have a good germination rate. If you’re worried about the viability of the seeds use the paper towel method to sprout them.
Soil temperature is the deciding factor for how fast germination will take place.
Watermelon are warm weather plants that shouldn’t be planted until soil temperatures have reached 70 degrees. Watermelon seeds should sprout in 3-14 days, faster with warmer temperatures and slower with colder temperatures.
A soil thermometer is an inexpensive tool that combined with knowing when the last frost date is the best way of knowing when you can plant different garden plants outside. Measure soil temperatures between 9-11AM or throughout the day for a good average.
Moisture is the other critical factor in germination. Moisture activates catalysts within the seeds that start the germination process. It also softens the shell of the seed and mixes with proteins or starches within the seed to form a soluble that will feed the plant embryo. That’s why the next step is so important.
Water Watermelon Seeds After Planting
Watermelon seeds should be watered directly after planting and while they are germinating under the ground.
Watering directly after planting has two purposes: to set the seeds you just planted in place and to provide them with the moisture they need to germinate.
Keep the soil around seeds moist but not drenched by waiting until it has almost dried to water again. Water with room temperature water. If you’re using tap water let the water sit for a day or more in a pan or something with a lot of surface area to allow chlorine to dissipate.
How to Plant Watermelon Seeds in a Pot
Watermelon plants need 3-5 gallons of soil apiece so in a 10 gallon pot you can plant 2-3 watermelon seeds. Use shapes to plant seeds in well spaced patterns: a triangle, diamond, pentagon, hexagon.
Use your finger or a pen to make holes 1/2″ deep. Place seeds in the holes, cover with dirt, and water in gently.
Plant Watermelon Seeds in a Raised Bed or Garden Plot
Planting watermelons in a 4’x8′ raised bed is easy. Plant watermelon seeds every 2′ along the 8′ wall. This will give 4 watermelon plants with 8 square feet apiece to grow.
Check out this article too learn more about how watermelon plant spacing affects yields.
In a garden plot make watermelon rows every 4′-5′ apart by using a stick or tool to make a line where the row will be 1″ deep. Plant seeds every 24″ apart, cover with dirt, and water in gently.
Prepare Soil for Planting Watermelon
Watermelons generally grow best with loose sandy loam soil and have roots that regularly reach between 8-16 inches. Break up soil 18″ deep with a pitchfork or shovel. This will loosen any compacted soil and help the soil warm up faster and dry out.
Fertilizer is key for good yields and almost all gardeners need to use some fertilizer. Even if you’ve been composting your butt off I still recommend using some form of all-purpose fertilizer with a solid dose of the macronutrients. MySoil test kit is an inexpensive soil test that will tell you the levels of 13 nutrients and your soil PH.
Organic Plant Magic is a great organic fertilizer. It has a lot of different organic materials in the mix and 55 trace minerals and 13 different beneficial bacteria strains.
Jack’s Classic is a great standard water soluble fertilizer that measures 20-20-20. Garden-Tone and Jobe’s Organic are other good organic brands.
Please comment below with your own thoughts and experiences on getting watermelon plants started.