How To Grow Watermelon In A Pot – A Personal Guide

If the whole summer could be put in one word, that word would be “watermelon.” The sweet, juicy and aromatic plant which makes my mouth watering just thinking about it. Last winter, I felt sorry for not finding any off-season, and I have decided to correct that.

But, how to grow watermelon in a pot, since it can become so big? I thought that would be difficult, while it was fun and rewarding at the end. Feel free to use my guide, so you can have a slice of heaven anytime you like.

I have grown it during late fall and the beginning of winter, but you can use the guide for any time of the year.

How To Grow Watermelon In A Pot

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What To Know About Watermelons?

Watermelon

Here are some interesting facts about this beautiful fruit which you surely didn’t know:

  • Watermelons require a lot of space; in general around 5 gallon of soil is required per plant
  • The soil should be in 6-6.8 pH value
  • Seeding season is in spring, once the soil gets heated enough
  • leaf
    Before flowers appear, nitrogen is required more, and after phosphorous and potassium have more important role
  • leaf
    Separating the fruit from the wet ground is of utmost importance

Planning Ahead

Once I’ve put everything on paper, I have realized that proper planning (and slight arrangements) need to be done. Since watermelons require a lot of space and sun, the first thing I took into consideration is to place it in my covered terrace. This area is tightly sealed, so I had no fear about winter winds finding their way in. The best thing about it was that it was positioned at the sunny side of the house. Those fruits require a lot of sunlight as well, so the second condition was also fulfilled.

The ideal temperature for growing watermelons is around 80°F. Since my terrace can get a bit chilly during winter, I’ve put portable heater there, to keep the temperature at the required level. An ordinary thermometer was needed, so I put one closer to the window, to monitor the lowest temperature in the room.

As for the container, I was in doubt. I knew that watermelons need a deep container, but somehow bucket was too inconvenient. Instead, I took my trusty hammer and made two wooden crates. The size of the container was 16” deep and 23” wide. This measure is for larger varieties, but I didn’t want to take any risks. Simply put, the bigger, the better, if you can provide the space. Also, the crate must have enough drainage holes, because despite watermelons love water, the soil must be well drained.

To further improve drainage, I have made three rows of holes at the bottom and lifted the crate from the ground (putting four bricks at corners will do the trick). That way I could place the tray underneath to collect the water which drips and can create a mess.

Choosing The Soil 

Choosing The Soil

Since the volume of the crate was quite large, I’ve decided to buy pot soil in bulk. The ordinary kind, which is used for flowers in pots will do the trick. Although it is a common practice, I haven’t mixed in any soil from the garden. Even if it is economical, this kind of soil has a nasty habit of settling and becoming hard and dense. This is opposite of which watermelon prefers; the soil must be loose and well aired.

As for the acidity, these watermelons can grow in soil with pH from 5 to 7, but their ideal conditions include slightly acidic surrounding with pH between 6 and 6.8. The best thing about buying soil is that you can find precisely that which is needed. No need for messing with sulfur and limestone.

If it is required, and you can obtain it, cow manure had shown to be the most efficient in the preparation of the soil. I have poured the potting soil in a large crate, added manure and turned it once a day, to keep it going, and to remain aerated. Speaking of manure and fertilizers, if you prefer NPK-based ones, it should be labeled 15:15:15, because watermelons are quite hungry, and need a balanced nutrition. Still, do not exaggerate, since too much fertilizer can burn the roots of the plant.

Which Variety To Choose?

Kinds Of Watermelon

Among so many species and hybrid-made varieties, it is sometimes hard to make a decision. Luckily, Washington State University made this chart of the most commonly used ones. My personal favorites are Betsy 8103 and Cathay Belle. They are not too large in volume, are enough fast growers (87 and 82 days respectively), and their sweetness is just as I like it. The lack of seeds is also an advantage for me, because every time I bite one, I’m scared that it is my tooth.

Of course, if you lack space, Pony Yellow, New Hampshire Golden Midget and Hime Kansen are great ones to consider. They grow up to 3.5 pounds and are different in sweetness.

Aside from these factors, nothing separates different varieties. All of them will require approximately the same care, so it is just a matter of which do you prefer. Ultimately, if you can’t make a decision, choose several types, and make things interesting.

The Planting

Planting

Consider that in average, watermelon needs about 80 to 90 days to grow fully. I wanted them to be ready for harvesting at the beginning of November, so I put the crate on my terrace at the end of July. Of course, you can use warm weather during summer for the seed to start growing, but this somehow complicates the process. Instead, I have chosen to start in crate immediately.

The box was filled with about 2” from the top because there might be adding of fertilizer and manure later. By using what you have at disposal (back side of the ladle or a finger) poke a hole in the soil about 1” deep. Put 3-4 seeds inside and cover it with soil. Since I have made larger crate then which was needed, I have poked two holes and put four seeds in each.

Right after planting, I have watered the seed, covered it and tapped lightly. This way the soil was compact, so it retained water underneath. The water is essential for this early stage, so providing it at least once a day is a must. 

The First Leaves

After about a week (period may vary) the first sprouts will appear. This means that the time is right for some thinning out. I have chosen to leave only two of the strongest plants in every hole, and that is advice I can give it to you as well.

Fertilization at this point was more or less the same, only that I have accented intake of nitrogen, for the stem to grow stronger and thicker. My preference was to use a slow-releasing type of equal proportion (already mentioned 15:15:15), and to accent which was needed with liquid fertilizer.

Fertilization was done once a week, so that intake of nutrients was stable and regular. When flowers appear, this usually means a change of course. Potassium in most and phosphorus as well was required, so I have accented those as required.

First Leaves

Since there were no bees or other insects which are performing the pollination, I had to do it by hand, and it was a fun and exciting experience. 

Climbing The Pole

Climbing The Pole

As the plant progresses, its vines will become longer and longer. The best solution for me was to build a climbing pole and to direct the plant upwards. To do this, a trellis or a tepee is required, and in case that you have never done this, there is an article which can shed some light on this matter.

The vines were progressing upwards, so I had to take care about sprouts. Leaving only one vine which will be the main, I have removed others. My grandmother used to call these “water drinkers” since that was the only purpose of these side-branches, to draw strength from the main stem.

Hammock For Watermelons (Yes, You Read That Right)

Hammock For Watermelons

After the development of the first fruit, I have realized that supporting them since the vine was charging upward was much needed. Still, the fruits were smaller than my fist, but I had to plan. 

By using an old t-shirt, I made a little hammock for every fruit which appeared and tied it to the trellis. Be aware that the trellis needs to be robust enough to support the weight of the watermelons.

In case that your plant gave fruit close to the ground, you must separate the two. Straw is commonly used as an isolator, so the moist from the soil won’t ruin the fruit. It is also considered as good fertilizer, and why not to hit two birds with one stone?

This was also the time when my watering changed. Namely, once the fruits are developed, watering should be gradually reduced. Too much water will ruin the taste, and you will have a feeling as if you are eating a wet sponge (yuck!). With the absence of water, the sugar builds up, and thus the taste. Of course, do not leave the soil completely dry.

Some people are advising to tie the fruit directly to the trellis, to lift it up, but I didn’t like that approach. This one appeared as more comfortable and flexible.

Knock, Knock!

Harvesting

After about 80-100 days the watermelon should be ready for harvesting. This is, however, individual and varies from species to species. What does not vary is the sound it makes when you knock on the fruit. 

If it seems as hollow inside, you can freely cut it out and put it on the table. If not, give it a bit more time. This method was the only upon which I could rely on with 95% of accuracy, so I’m advising you to do the same.

What To Look After

Since watermelons don’t have so many enemies such as let’s say, cabbage, people forget that there are still some things which must be taken into consideration, for harvest to be productive. Overwatering is the worst thing which can be done to a watermelon plant, because its roots are gentle and sensitive, and will quickly become rotten, and the plant will almost certainly dry out.

Aphids are persistent and greedy little critters which will respect no boundaries and can migrate from other plants in the vicinity. So you must check the plant regularly, and remove them if they appear.

Conclusion

Watermelons are great plants. Although they are sensitive and demanding, the reward is definitely worth the trouble. How to grow watermelon in a pot is possible, as I have shown it, so there is no reason for you not to try it. After all, you will be rewarded with the essence of summer.

Of course, I’d love to hear from you; all of your tips, advice and general thoughts are more than welcome in the comment section below.

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