Growing Watermelon from Seed


Growing Watermelon from Seed

by Rob Sproule


Watermelons are a marquis fruit that have the unfortunate reputation of being impossible to grow in Alberta.   Nothing is impossible if you know the tricks!

The secrets to growing watermelon in Alberta include starting them early indoors and knowing which varieties to grow.   With nutrient rich soil, a little love, and some luck from Mother Nature, you could be munching on your own home-grown watermelon this fall.

From Seed to Seedling

I’ll start with the bad news.   Although the watermelon seeds you’ve diligently kept from your picnic last summer will probably grow, it’s probably won’t turn into the same watermelon.   Seeds kept from hybridized varieties rarely produce true offspring.

Plant your seeds in the richest soil possible at about 2-3 times deeper than the seed itself.   As long as you keep the soil moist and above 18 degrees your watermelon plant should emerge in a few days.

I wouldn’t bother sowing into small seed trays because the plant will quickly outgrow it.   The goal with watermelons is to transplant them as few times as possible.   I recommend planting directly into a 4 or 6 inch pot where it will have room to grow and you’ll only have to transplant once.

The type of watermelon you choose to grow will depend on how you want to grow it.   Unless you love to gamble, I wouldn’t recommend growing the giant, supermarket sized watermelons in Alberta.

Luckily, there are several miniature varieties that grow well even in our short season.   My personal favourite is “˜Sugar Baby’, which produces very sweet, dark green fruit that is about 8 inches in diameter.

Smaller varieties thrive in containers where the roots stay warm and they are protected from invasive weeds.

From Seedling to Eating

Watermelons don’t like to be transplanted but it’s unavoidable when growing them from seed.   Be extra careful not to damage the fragile root system and try to keep your movements slow and steady.

For a nutrient boost, add extra compost or “˜Sea Soil’ to your soil before planting.   A layer of mulch around them will help keep their root systems evenly moist.

If you’re planting your watermelon into a container, make sure that it’s about a 5 gallon pot size or larger with ample drainage.   If you have a tiny patio, watch out.   Watermelons have fast growing, greedy vines that will quickly take over a small space garden.

To grow your watermelons in the garden, wait until the soil has warmed slightly before planting.   Mound the soil up into small hills so that the roots are protected from the chill of the deep earth.   Mounds also provide excellent drainage; they hate wet feet.

Watermelons thrive in long, hot summers.   Although the larger varieties require 3 solid months of warm sunny days to set fruit, “˜Sugar Baby’ takes about 80 days from seed to harvest.   The warmer the summer is, the sweeter the fruit will be.

Most people focus on the disadvantages to growing watermelons in Alberta, but I prefer to think of the advantages we have.   One is that the fungal diseases that afflict watermelons in tropical climates have a hard time getting established in our dry air.   You can help by watering in the morning and trying to get as little water on the leaves as possible.

Harvesting and Uses

There is quite an art to knowing when a watermelon is ripe.   There are a few reliable ways to tell.

Watch the curly tendril at the stem.   Once it is completely dry (about to fall off), the fruit is probably ripe.

Another way to tell is to knock the fruit with your knuckles.   Unripe melons with have a higher pitched sound than ripe ones, which sound dull and hollow.

Of course, the best way to eat a summer sweetened water melon is fresh from the vine.   You’ll be amazing how much sweeter and flavourful a garden grown watermelon is than one bought in a supermarket.


Read through our Growing Guides for tips to enrich your garden! 

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