Growing watermelons requires lots of space, sun, water and nutrients.

They are greedy, rambling vines, like all plants in the Cucurbitaceae family (e.g. zucchini, squash, pumpkin, cucumbers)

Watermelons are not particularly difficult to grow, but because they are so demanding they might not exactly be a good plant for beginner gardeners. (You can get lucky if you live in optimum conditions).

They are also not particularly a good option for anyone with restricted space or water, or average soils.

You need to put a lot into a watermelon, and what you get out in terms of nutrition is not a lot… So from a permaculture point of view, watermelons wouldn’t be the very first thing to worry about…

But too many questions often arise about growing watermelons. They are very popular. So in this post, we will run through a few of them.

How To Grow Watermelons

Where and when can you grow watermelons?

In the true tropics the dry season (winter) is the best watermelon growing season.

Watermelons do not cope well with extreme heat or the humid, soggy conditions of our wet season/summer. Fungal diseases and bugs will wipe them out in no time.

If you live in a cooler climate, then summer is the time to grow watermelons.

You do need at least three months of reliably hot, sunny weather to grow and ripen a watermelon. During that time your average daily maximum temperature should be at least about 20-25°C or 70-80F. Warmer is even better.

(There are different watermelon varieties, so if you are at the low end of that, look for a faster maturing variety.)

Grow watermelons in full sun. You also need an abundant supply of water and nutrients (good soil).

And you need space. As I said, a rambling vine. They like to go wandering and smother everything around them.

Growing watermelons from seed

Watermelons are grown from seed. You may be tempted to use seed out of a melon you bought, but don’t waste your time. It is almost guaranteed to be a hybrid.

Hybrid varieties are very special crosses that don’t grow true to type. (You would end up growing what we call pig melons. A melon variety that’s only good for feeding to the pigs…)

Buy your seed, and if possible buy an open-pollinated heirloom variety. Because then you CAN use your own seed next year. The open-pollinated varieties are also hardier.

You will find a lot more interesting varieties amongst the heirlooms than you can find in the standard collection of your local gardening centre.

Start your watermelon seeds in the ground, right where they are supposed to grow. The soil should be at least 18°C for them to germinate.

Unless you have an extremely short growing season, do NOT start your watermelon seed in a pot or punnet. Do NOT buy watermelon seedlings from a nursery.

Watermelon seed germinates easily and quickly, within a few days. Watermelon plants outgrow the seedling stage very quickly, and they don’t like transplanting. You don’t save much time and you end up with a weaker plant.

Save yourself this totally needless extra work and stick your seeds in the ground, about two cm or an inch deep.

(If you have a long growing season, you may want to do several plantings, a few weeks apart.)

Watermelons need deep, rich, friable soils. To grow watermelons it helps to raise the soil (make mounds or ridges). Raising the soil has several advantages:

A mound or ridge is free draining (melons don’t like wet feet). If you have heavy clay soil, definitely raise the bed.

Mounds are also good if the soil is as poor as mine. I just make a mound of good soil with lots of compost in it to grow watermelons. Sometimes I plant them in what’s left over from a compost pile after I used most of the compost.

If you like growing things in neat rows, or if you want to plant a large area, grow watermelons on ridges, like the commercial growers do.

Rows should be about 2 m (6 ft) apart and the plants spaced at 30 cm/a foot apart. (Sow twice as many as you want, and keep the stronger ones.)

I prefer growing watermelons in clumps on a mound, in several different locations in the garden. (Mixing things up helps keeping pests and diseases at bay.) If you want several hills together, keep them about 2 m apart.

The mound should be about one-metre square and a foot high. Then I plant about ten seeds in it, in three groups of three to four seeds each. The groups are spaced about a foot apart (30 cm).

After a few weeks I can see which watermelon plants grow the strongest, and I snip off the weaker ones, leaving only one seedling in each group. (Don’t pull them up, cut them off. Or you disturb the roots of the others.)

You need a very strong trellis, you need to train them up the trellis as they aren’t climbers, and you need to support the developing fruit so the trellis holds the weight, not the plant.

It is a lot of work but it can be done…

Growing watermelon plants

Slugs and other seedling chomping critters like mulch and they like watermelons. Wait until the watermelons have outgrown the most vulnerable stage (where a slug can demolish them within minutes). Then mulch the area well.

Watermelons have very shallow roots and they need lots of moisture. The soil should never dry out, and mulch helps with that.

Mulch also keeps weeds down. Weeding could disturb the shallow roots, so it’s better to not let them grow to start with.

Watermelons are VERY hungry plants. If your mulch is something like compost or aged animal manures, all the better. (Like all cucurbits, watermelons can handle fairly raw compost and manures.)

Otherwise, feed your watermelons regularly with something like pelleted chook manure or another organic fertiliser. (Ideally you should use a high nitrogen fertiliser in the early stages, but cut back on nitrogen and give them lots of potassium once they flower and fruit.)

When the vines are about two metres long, pinch out the tips. It encourages branching.

As your watermelon vines grow bigger they will start trying to take over more space. If they start to smother other things you can remind them about sticking to their area by gently moving the tips of the vines, so they grow in the right direction.

Source: tropicalpermaculture