I've been considering the possibility of grafting a giant watermelon variety (such as Carolina Cross) onto a giant pumpkin/squash/gourd rootstock (such as Atlantic Giant pumpkin, Weeks NC Giant, Zucca gourd, or Kikinda Competition Strain Edible Gourd). Would that affect the size of the fruit, ease of growth, and productivity, at all? I understand grafting onto squash and gourds can affect some aspects of fruit, such as firmness, at least.

Anyway, I'm hoping this might result in unusually large fruit, or at least easier to grow fruit in less than ideal conditions.

'Ease of growth' probably needs further explanation. Basically, I mean, Might it make it easier to grow large fruits (not giant, per se) without special treatment? For instance, Zucca gourds don't require special treatment to grow large, but people who grow giant watermelons and pumpkins usually report all kinds of tricks employed to get them huge (not that Zucca gourds are that big, though).

From what I read, it sounds like a gourd might be better for a rootstock than C. maxima x C. moschata, if I want good quality fruit. I'm not sure about plain old C. maxima.

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    I'm not sure if they're compatible. If they are, scion to stick grafts by would be extremely risky. You'd have better luck growing the plants side by side, and semi splicing the stems, only cutting the original root of the splice takes
    – J. Musser
    Dec 22, 2016 at 18:09
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    @stormy check this out. Grafting vegetables is becoming popular for improved yields, and in my experience they're worth the expense. Usually done with the more substantial nightshade family (peppers, tomatoes, eggplants). I've never seen it done with the watery, hollow stems in the squash family
    – J. Musser
    Dec 23, 2016 at 3:23
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    When we were growing eggplants commercially we were advised that grafting them onto tomato rootstock would give the plants an extra 3-6 months productive yield. This did not make bigger vegetables, just more of them, and, of-course resistance to phytophthora.
    – davidgo
    Dec 23, 2016 at 3:40
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    Grafting watermelons and cucumbers onto squash/gourd rootstocks is done, whether or not it's common (I believe at the seedling stage). They're considering using bottle gourds as rootstocks to help watermelon have firmer flesh (so it doesn't get mushy too fast in fruit trays and stuff). I don't know that anyone has experimented with giant watermelons on giant squash/gourd rootstocks, though. It's likely they usually try smaller-fruited rootstocks. I know they've successfully grafted watermelons onto C. maxima x C. moschata, and the bottle gourd species, and probably C. ficifolia, too. Dec 23, 2016 at 6:22
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    @stormy As I understand it, phytophthora is in the root of the plants - some types of tomatoes are a lot more resistant to it then others - so getting my eggplants grafted on to the appropriate rootstock makes the plant a lot more resistant to phytophthora.
    – davidgo
    Dec 23, 2016 at 10:17

1 Answer 1


No, it should not affect the size of the fruit. The size of the watermelons is determined by the watermelon veriety. If you graft cherry tomatoes onto a normal tomato stock it still produces cherry (sized) tomatoes.

Yes, it may make it easier to grow. This can range from root-related disease resistance to a difference in the fruit. Root related disease resistance has its obvious benefits while firmer flesh can help the watermelons be less susceptible to rot. The benefits will largely depend on what stock you choose to graft them onto. Be sure to pick a veriety that grows good in you area.

Yes, it may effect the productivity. The watermelons might be more likely to reach their full potential size and even grow a little faster. This can be because of a better root system from the grafted stock (the root disease resistance providing a healthier root system).

People who grow those insanely large pumpkins and watermelons usually tend to keep a lot of the methods used secret. I would say that grafting can certainly be the first step in helping your watermelons reach their full potential. Be aware that there might be even more tricks you need to learn to make them bigger than big.


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