There are several myths surrounding cross pollination in the vegetable garden. This post will help clear up those misconceptions.
I’m writing this post to clear up a common misconception about cross pollination in the vegetable garden. Over the last year alone I can think of at least 4 or 5 times where I have seen long discussion threads about cross pollination in the squash family. Even on the Stoney Acres Facebook page.
It usually goes something like this: “My acorn squash turned out all stringy like spaghetti squash this year. I think I must have planted them too close together and they cross pollinated”. This comment is then followed by a long discussion about how the same thing happened to me only it was cucumber and cantaloupe. Or “I fixed that problem by planting them on opposite sides of the garden”.
NO, MY FRIENDS!! THAT’S NOT HOW IT WORKS!!!!
Let’s talk about the science behind cross-pollination.
What is cross pollination?
Cross pollination is when the pollen from one plant is transported either by wind or insects to the flower of another plant. The genes from the two plants then combine to create a seed with genetic characteristics of both parents.
Cross pollination only occurs between members of the same botanical species.
The most prevalent pollination myth you hear about is in the botanical genus classification Cucurbita. Cucurbita includes many different varieties. Squash, Cucumbers, and Melons. But each of those 3 is just a botanical grouping and remember cross pollination can only occur between members of the same species. So Cucumbers CAN’T cross with squash and melons, Melon’s can’t cross with squash, etc.
But then it gets even more complicated. So remember cross pollination only occurs between members of the same botanical species. So even within the melon “family” you have limited cross pollination. For example, Watermelons and Cantaloupe are members of different botanical species and CANNOT cross.
But within botanical species, you can have cross pollination. So for example, Zucchini, Pumpkin, Acorn, and Spaghetti squash are all members of the same species (Cucurbita pepo). So all of these can cross with each other and produce seed that is a genetic combination of the two parents.
Cross Pollination does not mean funky fruit this year
Here’s where the common misconception or myth comes in. Cross pollination only affects the seeds, NOT THE FRUIT, this year.
So if a pumpkin and a zucchini cross pollinate the pumpkins and zucchini that you get this year will be perfectly fine, they will look right and taste right. That is because the type of fruit a plant produces this season is determined by the seed it was planted from, not the seed it will produce. So if a pumpkin and a zucchini cross you will have a Pumpcchini NEXT YEAR, when you plant the seed that was a result of the cross pollination. The combined genetic material is in the SEED, not the fruit.
Another common myth is if you plant sweet peppers and hot peppers together they will cross and all your peppers will be off. Again this is a myth. Yes, hot and sweet peppers are members of the same species, but the cross pollination affects the seeds, not the fruit!
So what does this mean for you? If you have funny shaped, funny tasting or funny colored fruit this year it is caused by one of two things:
- You planted a “bad seed”. If you are getting your seed from a reliable commercial source this is very unlikely. Commercial producers go to great pains to be sure there is no cross pollination in their seeds, but it does happen every once in a great while.
- Something else is wrong. If you have funny shaped, colored or tasting fruit the more likely culprit is some environmental problem. Look at what the weather has been like this season, was it extra hot or extra cool? Has the plant been damaged by pests or other means? Damage causes stress which causes funky fruit. What about herbicide? Is it possible you or your neighbor sprayed too close to the plant and the spray drifted? What is your soil like? You might want to get a soil test to see if your soil needs to be amended to replace missing minerals.
The point is, strange fruit is never caused by pollination issues in the current growing season. That is just not genetically possible!!
One Exception – Corn
There is one exception to this rule. And that is sweet corn. Crossing between sweet corn and either field or popcorn will ruin the sweet corn in the current season. But think about it, what part of the plant are we eating when we eat corn? The seed! So that is understandable. If you would like to learn more about how to deal with cross pollination in corn you can read this post I wrote on the topic last year.
Resources
I don’t want you to take my word alone for it on this topic, so below are links to a few articles I found on the topic of cross pollination, most of which are form agricultural university websites.
Pumpkins in the garden – Utah State University
What is cross pollination – Gardening Know How
Cross Pollination Crops – North Caroline State University
Cross Pollination of Melons – Susan Peterson
Here’s a handy cross-pollination guide
Using Tomato Cages in Your Garden
Got the yummiest and weirdest squash we called giganticus spaghetticus from planting a seed from enormous blue hubbards in an effort get more of those humongous specimens. We speculate it crossed with Italian striped zucchini, our favorite variety. Our local expert said we’d get a gourd and boy howdy he was wrong. It’s kind of fun to play with seed saving of squash if you like surprises.
The great thing about the whole squash family is they are so easy to cross and play with!! I’m curious, is this new squash stable? Meaning, have you saved seeds from the new squash combo and got the same plant the next year?
@Mr. Stoney, after watching your video, I believe I must have planted a crossed seed (i.e., pumpkin that is crossed with zucchini) because not only does the fruit look like a pumpcchini, but the leaves from the plant have the jagged lobes like zucchini leaves, surrounded by the rest of the more rounded pumpkin leaves. And it all came from the same seed packet! Do you think this is plausible? And can I still eat it?? Thanks!
That is possible, disfigured fruit could also come from stress to the plant, like heat or pests. Whether it is eatable is up to you!!??? 😉
What crosses with Chard?
Well, you usually harvest chard before any cross-pollination could occur. But if you are thinking of saving seeds then chard is in the same family as beets and spinach, and could possibly cross with them.
Just a note: Hot peppers and sweet peppers can cross-pollinate, as you mentioned, and you can tell they’re cross-pollinated in the current crop because the seeds are affected (and the seed membrane is where your “heat” comes from). Most people who grow hot peppers do it for the “heat,” and they consume the seeds in salsa, pico de gallo, and dried pepper flakes , for examples. When the seeds are compromised by cross-pollination, you can tell it from the reduced heat.
What about beans?
If you are planning on saving seeds then you will need to worry about cross-pollination. Otherwise, they will be fine.
The heat or mildness of the pepper itself is strictly determined by the genes of the mother. In other words, if a flower of a sweet pepper is pollinated by a hot pepper plant, it absolutely, positively will not make the sweet pepper hot.
I was going to plant bitter melon near kajari melons? Should that be of concern? Also, what about Kiwano. They already seem an absurd fruit somewhere between melon and cucumber, but I want to plant them.
It only matters if you are wanting to save seeds. If you are just growing for the fruit then cross pollination won’t affect this year’s crop.
Thank you Rick!
Hi! Love your posts and YouTube channel! I need your help/advise re: two different varieties of watermelon I planted this year and am wondering if I can save seeds from them. I planted 4 Silver Yamato and 4 Ambrosia watermelons in a raised bed not expecting to get anything due to our high altitude @5900+ and very cool, wet spring and early summer. Well, to our surprise, we did get some of each watermelon variety and really loved the Silver Yamato watermelon. Of course, we would love to save the seeds but are worried about cross pollination between the two watermelons. Would they have cross pollinated because they are each a watermelon? Or, are we o.k. to save the seeds? Thanks so much, Catherine
Unfortunately there is a good chance your two varieties of watermelon crossed. Watermelon doesn’t cross with any other squash family members, but they will cross with other watermelons.