by Amber

How To (& How Not To) Grow Watermelon Indoors

If you’re new to this whole business of growing your own food it’s a bit hard to envision the space requirements of different plants. And sometimes, we simply forget over time how gargantuan some of them really are. Even with a large outdoor garden proportional memory of how big squash and watermelon vines grow gets hazy over the winter. Eyeballing the area when installing those tiny little plants in June makes you feel like there’s so much wasted space, but come late August you’re dragging the stems out of areas for other plants and the aisle trying to contain it and train it.

Squash and melons are gigantic, sprawling plants. Grown vertically, the sheer weight of the fruit calls for a super-duper support system. They also require full sun for several months to produce a crop. In the north, you’re doing really well if a portion of the crop matures enough to harvest before frost sets in. Part of that has to do with average temperatures. These plants love heat.

So, I’m amazed to find that people are actually trying to grow something like watermelons inside the house, let alone in a little grow tent. The results aren’t good if you’re going the super economy route. The efficiency scale falls apart even when you’ve got all the latest and supposedly greatest equipment at your fingertips.

Here’s a high school agriculture program running an experiment with $3600 worth of LED lighting. Note that he says they’ve been growing them for 3.5 months in the video and the melons have only reached a little over 3 pounds. He doesn’t say what type of melons they are. They are round ones so they should be a smaller fruiting variety. Those all mature in about 80 days outdoors, which translates into just a little over 2.5 months. Small round watermelons are ready to harvest at somewhere between 4 and 8 pounds too, so maybe these were close, but still… how efficient is your indoor garden if the crop takes 2 months longer than outdoors? Is it worth investing almost $4k into lights burning 1000 watts of power to produce 3 watermelons in a third of a year?



Aah – and pollination is truly almost impossible beyond the realm of nature. So, it’s no surprise that this totally DIY approach below never bore fruit, though my initial suspicion was he doesn’t have enough light power for the plant to bloom. His garden space is very dim.



Now this doesn’t mean that you cannot succeed at growing watermelons indoors, but you need a greenhouse, not a grow room, or a desktop situation. Here’s a successful indoor hydroponic watermelon crop. Note his support system. The crop is efficient with natural light, though you might need auxiliary light if you try doing this in a northern winter. He is growing standard watermelons though, and harvested so many that he got tired of eating them!



Obviously, if you find yourself in this position, you’ll be looking for a way to sell a good part of your melon harvest. Or learning how to make watermelon wine, and pickles.

The smaller the fruit size at finish, the faster you’ll have ripe, juicy watermelon to feast on. Look into true minis like Little Baby Flower and Golden Midget that are ready to pick in only 70 days.

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The garden played a starring role from spring through fall in the house Amber was raised in. She has decades of experience growing plants from seeds and cuttings in the plot and pots.