The truth about Zumpkins

Family reunion - a selection of pepos and crosses. 

Here's a question you hear a lot:

"My zucchini looks funky. Did it cross with my melon?"

"Will my pumpkins and cucumbers cross if I grow them together?"

"Are my melons not sweet because I grew them with cucumbers?"

"Could my butternut have crossed with my pumpkin and that's why it is ripening/growing/looking weird?"

Okay, I admit that I am paraphrasing somewhat but these are all inspired by real life questions I have read or seen or answered on countless occasions. So to set the record straight, I give you the truth about the zumpkin.


Immature pumpkin scarred by design and by that I mean that we etched this face into it when it was green on the vine not that we intended on hurting it emotionally... 

Not all vines are created equal

I'm not suggesting that they fall into a heirarchy; what I'm referring to is how closely related they are. Cucumbers, melons, squash, zucchinis, pumpkins and more might look similar in that they are all leafy vines that produce (mostly) yellow flowers of which the female flowers swell into fruits but this does not mean that they can all cross.

In fact, crossing is usually only restricted to members of the same species. Just like how a rabbit must mate with another rabbit not a monkey to produce fertile offspring even though both rabbits and monkeys are mammals. (No jumping ahead, we'll talk about interspecies crossing in a minute.)

Plant: Genus species

Cucumbers: Cucumis sativa
Melon: Cucumis melo
Armenian cucumber: Cucumis melo (see it's tricky sometimes)
Watermelon: Citrullus lantana
Many (but not all) zucchini: Cucurbita pepo
Most halloween pumpkins: Cucurbita pepo (hence zumpkins)
Squash: Cucurbita pepo, Cucurbita moschata, Cucurbita maxima, etc...*

That's not to mention gourds (some decorative gourds are actually pumpkins), other things called melons and some more unusual cucumber like things such as mouse melon, aka Melothria scabra.

The more closely related something is, the more likely it can cross assuming that the reproductive mechanisms are conducive to such a union and there no other barriers. Peas, for example, don't tend to cross because they self pollinate even before the flower opens giving the bees no chance to create mayhem**! The vining crops mentioned above, on the other hand, are busy with pollen dusted buzzers moving between plants so cross pollination most certainly can happen if it is possible.

If they have the same Genus and species such as a pattypan and spaghetti squash and zucchini, they can easily create cross cultivar hybrids***. Some people let same species cross on purpose or just because they don't care but if you want to keep your seed pure, you have to isolate your varieties.

Sometimes you even get an wide-cross which is a cross between two different species. This is more likely between closely related species such as two types of Cucurbits rather than between a cuke and a watermelon. To go back to our mammal examples, sometimes you see a zonky (zebra + donkey) but no elephantice (elephant + mice)****. This species hopping hanky-panky is actually quite infrequent and apparently highly cultivar dependent according to what I've read (see link below).


Romanpan f1 = Romanesco x Patty Pan

Naughty neighbours?

What this does NOT mean is that if you are growing an Armenian cucumber beside your pickling cucumber that the fruit that forms will be some crazy mix between the two. It won't. Instead you will get just what you expect EVEN though you are growing two varieties.

The first year you grow two potentially cross pollinating plants will give you no pumpkin surprise. Honest. Growing pumpkin beside your zucchini will give you pumpkins on your pumpkin plant and zucchinis on your zucchini plant. Yup. Boring.


Patty Pan x Halloween Pumpkin = warty dumpling and ribbed white or Hallopans collectively

Hiding in the Seed

Actually not so boring. Those plants might be hiding a secret in the seed. You see, the next year when you grow out your pumpkin seeds, you may get fruit that doesn't look anything like you were expecting. It is year two that you get the Zumpkin.

Busy Bees pepo cross:


All together now: Romanpan f1 -> Romanesco -> patty pan -> halloween pumpkin -> Hallopan f1

To illustrate, in 2012, I grew white pattypans, romanesco and halloween pumpkins: all Cucurbita pepo. Some of my white pattypans were tossed to the chickens. The next year 2013, I moved their chicken run and out of it grew a great mound of volunteer pumpkin vines. Off the vines sprouted mainly what looks like pattypan x romanesco but there were also a few pattypan x pumpkin. I love the white pattypans not as immature little roasters but because they store exceptionally well mature holding their texture. We keep them in the cellar, peel and use as winter zucchini.  However, the shape is annoying as you have cut off a lot of the flesh. The chance cross of romapan-pattyesco gave me a better shape. We'll see if it stores and tastes as good.

From further a field, some pumpkin pollen made it to a pattypan flower creating a couple other variations which I'm less interested in but they look neat. Here's one below with a very thick hard rind but decent texture. Flavour is average zuke.

Now, I didn't isolate as I didn't realize what I had until later but I intend on saving seeds, growing out and doing some selection in years to come.


Inside one of the hallopans that we ate for supper. It's flesh was very pale but cooked up a bit darker. It held its texture well and tasted just fine.

A whole lot about Cucurbita seed production

* You are likely to grow these kinds but there are others as squash is a moniker given to a lot of fruit.
** That's not to say that crossing never happens and I seem to remember a reference to nectar stealing insects in beans that can trip up self pollination at the source which might also happen in peas. If you really, really want pure varieties of peas, there are suggested isolation distances.
*** Did you say hybrid?
Yes I did.
Aren't hybrids bad?
Depends on what you mean. A hybrid is just the crossing of two varieties. Anytime you don't isolate two cultivars of the same species, you might get a hybrid.
But?
Yes, agricultural hybrids that don't breed true and force people to buy their seed again so they become dependent on the system have drawbacks. That's the hybrid that people rally against in favour of what they call OP - open pollinated. The kind of hybrid above is just kooky. You are welcome to save seeds from it but no guarantees about what offspring you'll get. That's true of most commercial hybrids by the way too. Which is not to say that you can't try to select and stabilize a new OP variety from your crazy mix. That's fun too.
**** Yeah, yeah. I know. There are several reasons for that.