Garden Gossip

With Ted Smith

Over the past couple of Garden Gossip columns we’ve taken a fairly detailed look at growing pumpkins. There is still a lot of fun facts and information to explore in relation to those diverse gourds but it would likely be more fun to revisit this topic later in the season when everyone has their summer pumpkin harvest in hand. With that in mind, I’m just going to answer one pumpkin related question that I get on a regular basis and try to clear up an old misconception.

So every year at the farmers’ market I will have someone bring me a “squash” or “pumpkin” that is misshapen and off-colour. The story will be that they never planted anything like that and would like to know what they are growing. Almost as inevitable as being presented with this mystery fruit is the person who will chime in and suggest that the grower likely just planted their squash too close to their cucumbers or their melons too close to their pumpkins. This assertion will be followed by an explanation of how all these vine crops, when planted too closely, cross pollinate and result in ugly, unidentifiable and foul tasting fruit. This is a classic situation of a tiny fragment of fact growing into a mother lode of mythology and misinformation.

The first thing you should note in this discussion is that in the rare cases of cross pollination, you will not see the results in the current year. Instead, the effects of cross pollination only manifest themselves the following year when you plant seeds that have been cross pollinated and they grow up expressing genetic traits related to two different parents. Basically, if you are not saving seed for planting the following year, cross pollination is of no concern to you whatsoever and you could freely plant as many different vines as you wish in close proximity. Your cucumbers, melons, squash, zucchini and pumpkins can grow in a tangled mess and the fruit you get will be just as pure as the seeds you planted.

Where this all does become an issue is if you do plan to save your seeds for future years. The Cucurbitaceae family is comprised of pumpkins, summer squash, winter squash, all the many varieties of melons, cucumbers and gourds. Almost every member of this family is monoecious. This refers to the fact that male flowers and female flowers are distinctly different whereas most plants’ flowers contain both male and female parts. Monoecious flowers generally rely on pollinators such as bees. Since bees can travel great distances, isolation of crops to ensure no cross pollination can occur is often difficult. Fortunately, cross pollination is not nearly as common as a lot of garden folklore would have you believe. For members of the Cucurbitaceae family to cross pollinate, they need to be from the same genus and species. One good analogy I have come across compares cross pollination of unrelated Cucurbitaceaes to cross breeding between cardinals and blue jays. It just can’t happen. So the question then becomes, which Cucurbitaceae members are related and which ones are not?

The easiest way to lay this out is to describe which plants are in the same genus and species and therefore able to cross. The vast majority of pumpkins belong to Cucurbita pepo. Summer squash, most ornamental gourds, spaghetti squash and acorn squash all belong to this family and can cross pollinate with your pumpkins. The giant pumpkins belong to Cucurbita maxima as do hubbard squash and Turk’s turban gourds. These plants can cross pollinate each other. Some of the lesser know pumpkins such as the cheeses and cushaws belong with butternut squash in the Cucurbita moschata group. Virtually all cucumber varieties grown in the north are members of Cucumis sativus and can freely cross pollinate each other. Armenian, or snake, cucumbers share a group with muskmelons and honeydews known as Cucumis melo. Finally, watermelons and citrons are found in Citrullus lanatas and can only cross pollinate within themselves.

As you can see, cross pollination is actually a much more difficult prospect than most common garden lore would have you believe. If you want to save seeds you could easily grow one variety from each of the above groups and be assured that any seeds you save will be pure…unless you have nearby neighbours growing a different Cucurbitaceae from the same genus and species. Then you will have to engage in slightly more complex isolation practices.

So about that lumpy bumpy oddball squash that was brought to the market for identification. It would have been grown from a seed that had been cross pollinated the previous year. And if your squash and pumpkins taste bad, that’s a husbandry issue, not a “this season” cross pollination problem. Clear now?