Growing delicious Watermelons in Melbourne

What is your favourite fruit on a sweltering hot day in Melbourne? I’m quite partial to a cold slice of refreshing watermelon. Did you know that watermelon will grow just as well in Melbourne as other parts of the country? It all comes down to the timing. Watermelon does not like wintry weather, but there is still time to grow this delicious juicy fruit, especially if you plant straight after the last expected winter frosts.

Growing Watermelons in Melbourne
Watermelon growing on the vine

When to plant Watermelons in Melbourne

As I mentioned above, watermelons are sensitive to frosts. If you are planting straight into a garden bed, it is best to wait until the chances of frosts have passed, then wait another 2 weeks so the ground has had a chance to warm up a little before planting. Ideally, waiting until the end of September/ beginning of October through to mid-November will yield the best results.

You can plant earlier if you are in a warmer area, but just be mindful of frosts. You can get around this by planting in good sized pots in a sunny warm spot in a green house or somewhere that’s warm. Just be careful not to damage the roots and stem when transplanting into the garden.

Choosing a site to plant your watermelon seeds

Watermelons grow on a vine, so you will need a fair bit of room for them to grow freely. It is recommended that you have around two square metres per planting space. Believe it or not, you can grow watermelons over a fence or shade structure which will take up less room in the garden as well as giving the vine more air circulation which will help in preventing diseases like powdery mildew.

Two critical elements required to successfully grow and harvest watermelons are warmth and sunlight. Although watermelons like a drink, they dislike soggy wet ground.

Soil preparation

Watermelons love well-drained, humus rich and nutrient dense soil to thrive. Watermelons have a deep and fine root system, so the soil needs to be well cultivated so these roots can grow down and really spread out to be able to access the moisture and nutrients so they can feed the rapidly growing vine as well as the fruit when they start to bear.

Planting your watermelon seeds

Now that you have picked your location and are sure there are no more frosts expected, you’re ready to plant your watermelon seeds.

Planting the watermelon seeds

I like to make mounds in the garden around 30cm high and 70 cm across, hollowing out the centre to form a “basin” into which I plant the seeds. This allows for drainage and a provides a means for watering your watermelons - more about that later. Space the mounds at around 75cm apart from each other.

Plant your seeds about twice the height of the seed with three seeds to a mound. Keep moist till they have germinated. You can start the growing of your seed indoors as well. Make sure to choose a pot that is larger than you would usually use so there is room for root development, like the ones you see in a plant nursery or 100mm pots. That size will hold them for a couple of weeks without becoming root bound.

Create a mound with a basin for planting the vines

Growing Watermelons on a fence

Watermelons will climb a little by themselves, but you will have to train them at the start. The tentacles will grab on, but a few ties here and there will also help.

When the vine has started to set fruit, you will notice that the fruit will start to pull the vines down due to the weight of the fruit. This is the time to get a little inventive! You will need to make a sling out of something to hold the fruit up and take the weight off the vine. I have seen slings made out of shade cloth, cotton sheets and pillowcases, it doesn’t matter as long as it is strong.

Remember, watermelons can weigh upwards of 15kgs or even more. Tie each end of your sling to the fence so that the fruit is supported, leaving a little room for expansion of the melon. Think of it as a hammock for the watermelon.

Supporting the growing melons with a sling
Supporting watermelons on the vine
Supporting watermelons on the vine

Watering your watermelon vines

Give your watermelons a good watering once a week or more often if the vines are showing distress from lack of moisture. This is where the “basin” comes into play that you made in the mounds for planting. Put your hose into the basin on a steady trickle and fill the basin with water.

It is important not to wet the watermelon leaves if you can help it, watermelons are prone to powdery mildew and by watering at the base of the vine helps to eliminate that issue. Only watering at the base of the vine saves water and helps to control weeds.

Harvesting your Watermelon

Watermelons are a long-term crop taking anywhere between 80 and 120 days depending on the variety and growing conditions. Warpaint takes about 80 days as with Sugar baby and Charleston grey upwards of 120 days.

There are three basic things to look for as the watermelon starts to mature.

  • The bottom or underside will start to turn yellow rather than white.
  • When you gently tap on the watermelon, they will start to sound hollow
  • The first two little tendrils closest to the melon will turn dry and brown as though they have died while the others further away are green and supple
Tendrils dying off near the fruit
Tendrils dying off near the fruit

To tell if a watermelon is ripe is a bit of guess work but if follow the above suggestions you are on the right track. Watermelons normally don’t all ripen together, so check out a few before deciding on whether the melon is ripe or not.

Unfortunately, the melon won’t ripen anymore after it has been picked and are best eaten within a day or two after picking to get the best out of the fruit, although they will store for a couple of weeks in the shade after picking.

Stages of watermelon ripeness
Different stages of watermelon ripeness

Happy gardening

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