Young watermelon fruit on trellis

If you’ve been avoiding growing watermelons because your garden is too small, wait no longer! You can grow a watermelon plant in a small 4′ x 4′ raised garden bed – if you use a trellis.

A single watermelon plant, given good growing conditions, can almost fill a 15-foot-wide circle on the ground. Yikes! There’s no avoiding that they are large, vigorous plants. But if you select the right variety, take good care of them, and train them up a trellis, you can enjoy fresh melons from your own small garden beds.

1) Make sure these plants get full sunlight – 8 hours or more.

Watermelons thrive in full sunlight.  However, a couple of years ago, I took a chance and planted a watermelon in a 50-square-foot bed (about 3′ x 16′) with two young 2-year-old espalier apple trees. It only received about 6 hours of sunlight, but I still harvested 3 large watermelons from that bed. So, sometimes you can succeed, even if you “break” the rules! Just don’t count on a good harvest with less than full sunlight of 8 hours or more.

Watermelon under espalier apple trees
This is a watermelon plant growing in a 50 square foot raised bed with two young espalier apple trees.

 

2) Give them the best soil, as deep as possible, in your raised bed.

Their root systems are massive. Just because they will be growing vertically up a trellis doesn’t mean that their roots will remain in a small area at the base of the trellis. These roots will go down as deep as they can, and sidewise for a long distance. I’ve found the roots growing several feet outside the small garden bed they were planted in.

This is one reason that I don’t put weed barrier under my raised garden beds. I want my plants to grow as large and vigorously as possible, to produce a big crop. Any time you restrict their root growth, the plant will become stunted and not produce as much.

Also, once their vines start taking off (maybe 3-4 feet long), I no longer grow other plants in the same bed with them. I give my watermelon plants the whole bed to themselves. But I still usually grow a spring crop before the watermelons, and a fall crop after them.

We built new garden beds last year, to make it easier for me to garden with my disability. These beds are made from concrete (cinder) blocks, and are 18 inches high, a little over 3 feet wide, and almost 16 feet long – for a total of 50 square feet each. These beds have the deepest soil I’ve ever used in my raised bed gardens, and I was frankly stunned at how large our harvests were last year.

Deep soil can have a huge difference on how well your plants grow. We planted 2 butternut squash plants and 3 watermelon plants in one of those beds. We used 4 trellises – two at each end – and grew the third watermelon plant on the soil in the middle.

We ended up harvesting 40 pounds of squash and 105 pounds of watermelon in just 50 square feet! Our friends and neighbors really loved us last year, as there was no way my sister and I could eat all that watermelon by ourselves.

Trellises supporting watermelon and squash
This 16 foot long raised bed has two watermelon trellises at the left end, two squash trellises at the right end, and a large watermelon plant growing on the bed in the middle. This one bed produced 105 pounds of watermelon and 40 pounds of squash!

 

3) Select a variety suited for trellising and your climate

Watermelons love hot weather and often take 90-100 days to mature. They generally don’t thrive in cool, cloudy climates or short growing seasons. However, some varieties have been bred to mature quickly or tolerate cooler weather.

I like to grow “Blacktail Mountain.” It can ripen in just 75 days, and will grow well in both cool and hot weather. It usually produces icebox melons, about 10 pounds, which is a nice size to trellis. I will be planting one  in late May and another in July, in order to extend the harvest.

But this variety really surprised us last year – one of the watermelons hanging on our trellis weighed 17 pounds! That one almost popped out of the sling we made out of nylons. I wouldn’t normally try to trellis melons that large, but we weren’t given a choice!

Watermelon hanging in a sling on a trellis
I used a nylon hose to support this trellised watermelon. Unfortunately, it didn’t know when to stop growing! This melon grew more than 50% larger than normal, and at 17 pounds, started to split open its sling. I wouldn’t normally expect to successfully trellis watermelons that large!

4) Don’t Plant Until the Soil is Warm

Wait until both the weather and the soil is warm before you plant them. Our average last spring frost is around May 15th, but I’ll often wait until late May for the best growing conditions. You can try babying your plants and starting them sooner under row cover, in a cold frame, or protected in a Wall-of-Water, but they simply don’t thrive in those conditions. After all that effort, you will usually only harvest melons a week or two earlier at most.

However, if you live in an area with an extremely short growing season, it may be the only way to grow watermelon at all. I’ve generally had better luck growing a fast maturing variety instead of trying to start them early before the weather warms up.

I prefer to plant the seeds directly in the garden bed, instead of using transplants. This is because direct-seeded plants tend to grow very large, vigorous root systems with deep taproots. Transplants often fail to develop taproots, and end up needing to be watered more frequently.

5) Build sturdy trellises!

Given deep soil and good growing conditions, I normally expect to harvest 20-30 pounds of watermelon growing on a 4 foot wide and 7 foot tall trellis. That’s a LOT of weight! Make sure your trellis is sturdy enough to hold that.

Our favorite trellis right now is made from a livestock panel cut in half and attached to two t-posts pounded into the soil. That will hold anything! I’ve also made trellises from wood frames and welded wire fencing, and have screwed these to the outside of small wooden garden beds.

I have learned that I can use trellises on both the north and south sides of my raised beds. The mid-summer sun is high in the sky, and will supply full sunlight to both trellises as it travels. Don’t put the trellises on the east and west sides, as they will shade each other as the sun moves across the sky.

6) Train the plants up the trellis

Watermelon plants grow fast – as much as 1-2 feet per week! They will not climb a trellis by themselves, so you need to tie the vines to the trellis as they grow. Don’t count on their tendrils to hold the plants secure – especially during wind storms or when they have heavy fruits hanging from them.

Watermelon vine on trellis
The large main vines dangling in the center need to be tied up. Watermelons will not naturally climb very far up a trellis, so we need to give them some assistance!

 

You can use any number of things to tie your plants to the trellis. My current favorite is surveyors tape. I like to use a loose figure-8 loop, wrapped just below a leaf joint, to hold the vines up.

Watermelon vine tied to a trellis
I like to tie up the vines at the base of a leaf axil. I use a loose figure-8 to attach them to the trellis. This photo is from a squash plant at the other end of the garden bed.

 

Watermelon vine are continually sending out new vines at nearly every leaf. I will train 8-10 main vines up my trellis, but I prune off ALL the side shoots they are sending out. Otherwise, the trellis will become very overgrown. Your fruit will obtain all the energy they need from the leaves on the main vines.

Side shoots from a watermelon plant
These are side shoots, growing out from a leaf axil. I prune them all off, leaving only the main vines to grow up the trellis. If I don’t, the trellis gets quickly overgrown. You can also see a baby watermelon growing in the corner of the cinder blocks.

 

7) Support your watermelon fruit with slings

Although butternut squash fruit never need to be supported, once the fruit of your watermelons start weighing more than a few pounds, they will fall off the vines and break. (Been there, done that!) You will need to support them by creating a sling attached to the trellis. You can make slings out of many different items. Some people use mesh onion bags, pieces of fabric, or even bird netting.

Last year, I used nylon stockings given to me by a friend. I cut two slings out of each leg, tied the bottoms closed and slit the top part of the nylons into two pieces so I could tie it to the trellis. You need to make sure that the sling will continue to support the watermelon as it grows. You don’t want it to stretch and sag so much that the weight of the melon ends up hanging from the vine instead of the sling.

A few of your early-pollinated melons will grow at the base of the vine, and can be supported by a brick or other object underneath them, if they don’t quite touch the ground.

8) Keep your melon plants well-watered

Vines growing on trellises are exposed to the wind, and lose more moisture than vines growing on the ground. Make sure you water your plants once or twice a week during dry weather. You want the water to soak deep into the soil. I also mulch the soil surface to slow evaporation.

This is the second reason I don’t use weed barrier under my raised beds. I want my plant roots to grow as deep as possible. This will let them reach moisture deep in the soil, and reduce how often I need to water them. If these large vines are growing in shallow 6” deep soil, you might need to water the plants every single day.

9) Harvest the melons when they become ripe, and enjoy!

Each watermelon is attached to the vine, opposite of a leaf. Next to the base of the watermelon stem will be a tendril. When that tendril turns brown and starts drying up, the watermelon will be ripe.

Now, if you only have 6 inches of topsoil in your raised garden beds, don’t worry! You can still grow watermelons on trellises. The plants just won’t grow as big, may produce a smaller harvest, and will probably need watering more often. But they’ll taste just as sweet! I’ve even grown watermelon in 20-gallon Smart Pots, and harvested 5 small watermelons from one pot.

Have fun growing your own watermelons in small garden beds, and enjoy your harvest!

You, too, can feast year-round from your backyard!

~ Debra

 

17-pound watermelon grown on trellis
This is a 17-pound watermelon that grew on our trellis last year. It’s miracle it didn’t fall off! I normally wouldn’t try trellising watermelons this big, but it just ended up growing a LOT larger than it should have. Yum!!


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23 Comments

  • C.C.

    Reply Reply May 1, 2014

    Can you tell me how tall your t-posts are? I have 5ft ones and I want to make a similar set-up. Thank you!

    • Debra

      Reply Reply May 1, 2014

      We’ve used 5.5 and 6-foot t-posts without a problem (about 1 foot of this is below ground). You might be OK with 5-foot posts, IF most of the weight is being carried lower down on the trellis. Most of my squash and melon fruit are growing within 4 feet of the soil, even if the rest of the vines grow much higher up the trellis than that. Livestock panels are fairly rigid, but can bend. A high wind and heavy load high up might cause the unsupported top half of the trellis to bend over. I’ve not seen it happen, but it might be possible. I think you’ll be OK.

      • C.C.

        Reply Reply May 1, 2014

        Thank you so much! I was very worried. I will try to sink the panels a bit further into the ground for peace of mind.

        • Debra

          May 1, 2014

          You’re welcome! Good luck!

  • Nate

    Reply Reply May 7, 2014

    We are interested in trying the trellis for watermelons and pumpkins. How many plants did you put per trellis? We normally put 3 plants per mound but didn’t know if this would overload the trellis. Thanks!

    • Debra

      Reply Reply May 7, 2014

      Hi, Nate! I have put as many as 2 butternut squash plants on one 4 foot wide by 7 foot tall trellis, but I grew larger, better quality squash fruit when I only put one plant on that size trellis. I seemed to do OK with 2 watermelon plants per trellis, but I haven’t really tested it out with just one. I haven’t grown pumpkins at all, but I think they would be similar to squash plants – though their fruit might need support with slings if they grow to more than a few pounds in size. My butternut fruit never needed slings, but I’m not sure about large pumpkins. Best wishes with your garden!

  • Toby Henderson

    Reply Reply May 11, 2014

    This is really neat I would like to try those cattle pannels next year and also do beds… my butternut squash is doing well yet I will never grow squash or cucumber with out a raised bed…ever again. The Florida sandy soil seems to be bad for it… Powdery mildew and all that. any way I just recently did a vid of our watermelon patch any helpful hints would be greatly appreciated… http://wormcastings.net/watermelon-growing-secrets/ :D

    • Debra

      Reply Reply May 11, 2014

      Hi, Toby! Thanks for visiting. I’ll visit your page to make any suggestions there.

  • Toby Henderson

    Reply Reply May 16, 2014

    Thats great Debra I took a bunch of grass out of the watermelons… we have many growing now… I did cut the tendrils annd lowered a couple vines off the fence… the small canteloupes I think I am going to leave… they are very prolific by the way with the addition of castings… try the Sarahs Choice Canteloupe … P.S. Not going to add boron this year next year I will most definately test all soil and go automatic watering…

    • Debra

      Reply Reply May 16, 2014

      Good for you, Toby! Best wishes for your watermelons!

      We’ve had a small worm bin in our basement for the last year or two. The worms have been multiplying like crazy, so today my sister built a LARGE worm bin (3′ x 4′) in our hoop house. We have partially rotted bedding from our outdoor chicken pen (dried leaves, weeds, and chicken manure), along with grass cuttings, and rotted kitchen scraps we collected all winter long in an outdoor garbage can. All moistened well. Now we’ll let it sit for a few days, to make sure it won’t heat up too much before we add any worms.

  • Abby

    Reply Reply May 19, 2014

    Out of curiosity, what did you use to tie the panels to the T-posts?

    Also, I’m not a fan of melons, but my family is, at what point (size wise – like softball size or bigger??) did you need the slings? We are going to grow sugar baby watermelons, I think, so I suppose we don’t need as tall of a vining trellis.

    • Debra

      Reply Reply May 20, 2014

      Hi, Abby! As we move our trellises around every year, I just use zip ties. You could use wire or sturdy twine, too, I suppose. The bottom of the panels rest on the ground, so the ties just keep it upright against the posts.

      Go ahead and start supporting the melons when they are about softball or fist size. And, yes, I always lost my melons if I didn’t use some kind of sling to support them. Sugar Baby is a great variety. I think its vines remain only 3-6 feet long. Have fun!

  • Jake Hartner

    Reply Reply May 27, 2014

    I love this. How far apart do you plant your watermelon plants and how many did you plant using the 2 Trellises? also I am planing on doing your design with my 3 foot wide beds, but I am worried about how I will harvest from between the 2 trellises, do you think I will have room to walk in between them?

    ,Jake

    • Debra

      Reply Reply May 27, 2014

      Hi, Jake! I’ve planted one or two watermelon plants per every 4 feet wide trellis (if it’s at least 6 feet high). My beds are only 3 feet wide, and I don’t have any problems fitting between the trellises. Just be sure to put down a board or something to step on, if you have to step inside the bed, so you don’t compress the soil. The 2 trellis design is easiest with a 4′x4′ garden bed size, as you never need to step on the bed to reach between the trellises. Have fun!

  • Jake Hartner

    Reply Reply May 29, 2014

    Awesome! That’s exactly what I ended up doing. I planted my watermelon starts 2 days ago and they seem to be adapting to the Trellises just fine. My Black Tail Mountain watermelon are about a foot high right now. I cant wait to see how they do! Thanks so much for taking the time to teach us how to do this.

    • Debra

      Reply Reply May 29, 2014

      You’re quite welcome, Jake! Glad I could help.

  • Valerie

    Reply Reply June 14, 2014

    Hi, I am a fairly at this. I planted Sugar Baby watermelon and Crimson Sweet watermelon. I do have other plants in my garden. Where can I find a sturdy trellis at a decent price? I realized yesterday that the vines are getting long and knew I needed a trellis.

    • Debra

      Reply Reply June 15, 2014

      Hi, Valerie! Sugar Baby watermelons are a nice size to trellis, as their melons only reach 6-12 pounds. However, you may have difficulty successfully trellising your Crimson Sweet, as those melons can easily reach 25 pounds. I’m not saying it can’t be done, as I once harvested a 17-pound melon off my trellis – though I don’t usually recommend it. But the trellis and slings need to be very strong if you want to try the large melons.

      I wouldn’t use the nylon string mesh for trellising in this situation. The strongest trellis I’ve used so far are livestock panels attached to t-posts. They can support just about anything, and will last for 15 years. One panel cut in half (our local store will cut it for you) will make two 4-foot by 7-foot trellises. In my area, one panel costs around $23, and the t-posts (6-foot, if you can) about $4 each. However, there are many other trellising options out there. I’ve often made trellises out of 2″ wood frames, with welded wire fencing stapled firmly to it.

      If you want to see various photos, type “trellis” into the search box in the sidebar of my website, and it will list all the articles with trellises. Best wishes! Let me know how it goes for you this year.

  • Veronica

    Reply Reply July 5, 2014

    Wow! THANK YOU for these instructions! As a first-time city gardener, I’ve been doing a lot of google searches, and I’m awfully grateful for your detailed and yet very easy to understand instructions on trellising.

    I found your post after stepping outside to water and thinking, “Whoa! Where did that six inches of watermelon vine come from? I swear that wasn’t there yesterday! I think I’m going to have to do something about this…” Thanks for telling me exactly what I was needing to know, and more!

    Also, great idea re: putting in early spring crops around them, but then clearing the bed out for watermelons-only when they’re really going great guns. Will try that next year!

    • Veronica

      Reply Reply July 5, 2014

      Also: because I am new and have decided to adopt a “learn as I go” approach to gardening (otherwise, I was finding that my internal perfectionist basically wanted me to become a plant expert before ever putting a seed in the ground!) I realize now that I probably have too many watermelon plants too close together:

      specifically, I’ve got four Sugar Babies in a recycled kiddie pool planter about 4′ in diameter. They’re really growing fast now that things have hotted up here in Massachusetts (probably should have seen that coming, but they seemed so innocent and slow-moving back in May…)

      Anyway, now I’m wondering:
      Would you advise moving any of these plants, or is it too late once they’ve gotten started and I should simply make the best of it for this year and learn for next year?

      • Debra

        Reply Reply July 6, 2014

        Hi, Veronica! Thank you so much for your kind words. I’m glad you’re finding my articles helpful. You are smart to decide to learn gardening by actually doing gardening! As much as you can learn by reading, you can only learn what works well for you in your current location by actually planting a garden. As for your current watermelon plants, I would just leave them for now and see how they do. I once planted 3 watermelon plants in a large 20-gallon Smart Pot, and harvested 5 small melons from them. So, I suspect you’ll be able to harvest something from your patch, even if they are a little crowded this year. Have fun! ~ Debra

  • LaShonda

    Reply Reply July 17, 2014

    Hello,

    I am growing sugar babies in a large barrel pot. They started off great but now after reaching the size of medium grapefruits, they seem to have stop growing. If the tendrils around them have turned brown do I still pick them and if so can they be eaten that small.

    • Debra

      Reply Reply July 17, 2014

      I’ve had some of my watermelons ripen at pretty small sizes when they were grown in containers and didn’t have a lot of room for their roots. Also, unless you’re using self-watering containers, container plants should be fed liquid fertilizer every 2 weeks after they reach a few weeks old, as many nutrients are leached out of the potting soil with the frequent watering that you have to give containers. If your plants are old enough, and the tendril at the base of the fruit has turned brown – then, yes, you should be able to harvest the fruit and enjoy it!

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