YES! Watermelons require a mound of soil when you plant their seeds which makes them perfect for planting in a pot.
Last year my kids planted “Sugar Baby” watermelons in 15 gallon “Smart Pots” I found at the garden center. I love that they fold flat for storage and take up very little space. Smart Pots feel like rough felt and are surprisingly durable. They cost $10. This year will be my second year with them and I am guessing I will get at least another 3 years out of them making it a total of $2.50 a year to grow watermelons. Yes, they need to be filled with potting soil and that can add to your cost. Don’t waste your money on bags of potting soil it is much cheaper to mix your own reusable potting mix using the recipe in Mel Bartholomew’s Square Foot Garden (recipe below).
When you have your potting soil ready; place the pots in a corner of your yard where watermelon vines will not be a bother. Small watermelons like “Sugar Baby” can grow up a trellis. Big melons are best left to sprawl on the ground. As the melons grow I put straw under them to keep them dry and protected.
Fill the pots, plant the 6 seeds, thin to 2 plants per pot when they are have their big true leaves, water regularly and don’t move them. In 100 days you will have watermelons! Last year our plants produced 6 melons each.
Mel’s Planting Mix
A Big Tarp
Bins to store any leftover potting mix; I use clean metal garbage cans (optional)
The rule of thumb for this potting mix is 1/3 peat moss, 1/3 vermiculite, 1/3 compost of 5 different types. The amounts listed below are smallest you can make to be the most cost effective and will make 12 cubic feet of mix. A 15 gallon Smart Pot needs 2.14 cubic feet of mix so this recipe will fill 5 pots.
*Peat Moss – 1 (3.9 cubic ft.) bales ($15)
*Coarse Vermiculite – 4 cubic feet ($17)
*5 different types/brands of compost equaling 4 cubic feet – I use Cow, Mushroom, Humus, and my homemade compost and worm castings (about $3/c.f.).
Lay out a tarp and place all the compost on the tarp. Take 2 corners (this is where 2 people are helpful) of the tarp and fold it over, rolling the mixture to the edge of the tarp. Next, grab the other corners and roll it back until it is mixed.
Add the vermiculite and the peat moss. If needed lightly spray to keep dust down but don’t over water or it will be heavy and difficult to mix and move. Again roll the mix back and forth to mix it up.
Fill your pots and place any leftover in the empty ingredient bags or a clean bin for future use. At the end of the season when the plants have died, remove them and the roots. Store the mix in bins or empty the bags. At the beginning of the next season simply replace what was lost with compost (preferably homemade) and refill your pots.
Total cost: $47 for 12 cubic feet of homemade potting mix that can be reused.
To put that in perspective: A 2.5 cubic foot bag of regular Miracle-Gro potting soil will cost around $14 (organic will run $18) so you would have to buy 5 bags to equal the homemade amount for a total of $70 and is only good for one season. Making your own will save you over $30 in the first year and $70 each consecutive year!