I usually harvest winter squash on or near the Fall Equinox, but this year I pulled squash and vines about a week early, partly because the crop was ready but more because there was real rain in the forecast. And as predicted, the day after the squash harvest, two inches of rain fell, glorious soaking rain that softened the soil of the squash bed and of all the other beds I’d cleared of summer vegetables and mulch in anticipation of rain.  After such a dry summer, the start of the rainy season was most welcome.

The joy of the rain made up for a smaller-than-usual squash harvest.  The yield in the main squash bed was half of what we usually get.  Among the drying vines, I found only two or three of old favorites Blue Kuri and Honeyboat and Zeppelin Delicatas, and barely more of new entries, Little Gem Red Kuri, Gill’s Golden Pippin, Sonca Butternut. 

 The one surprising exception was a large yield of Hunter Butternut squash from four plants that I’d set out at the last minute in another bed next to a Costata Romanesca Zucchini.

I’m not often successful growing butternut squash, but these plants produced sixteen lovely large squash.  Why did they do so well and the others so poorly? 

A number of factors affect squash production.  Days that are too cold and days that are too hot both affect squash plants’ fruit set.  We definitely had both extremes this summer. Lack of water is also a factor, but both beds received the same amount of irrigation. I never got around to mulching the main squash bed, but I did mulch the one zucchini and the four butternut plants, so perhaps mulch made a difference in moisture. More than moisture, though, there’s pollination.  In many of the trouble-shooting sources I turned to, pollination turned up as a factor affecting squash production.  An excellent entry on Squash Pollination by Mark MacDonald in West Coast Seeds Garden Wisdom Blog  helped me look more closely at the different conditions between my main squash bed and the smaller zucchini and butternut planting. 

Through text and photographs, MacDonald describes how squash pollination works and, in particular, the importance of bees to this process.  In his suggested solutions to poor squash pollination, he concludes: “This whole conversation illustrates the importance of bees in our landscape. It is their diligent work that spreads all of the pollen back and forth. Without bees, many crops would simply fail to produce. The first strategy for the squash grower is to encourage more bees.”

Looking at the two squash locations, I saw right away that the zucchini and butternut bed was next to a several sprawling calendula plants that had started blooming in early spring and bloomed heavily all summer. Next to the main squash bed were several cosmos plants, but they didn’t start blooming until later in the summer, and there were no other flowers nearby.  Maybe the explanation for my squash yield difference was simply poor pollination in the main squash bed.

I’ll hold on to that possibility for next year and plant flowers along with squash to attract bees. Flowers MacDonald suggests are alyssum, calendula, centaurea, crimson clover, nemophila, phacelia, sunflowers and white Dutch clover.  In a lovely description of bee behavior, he writes: “Sunflowers planted in the squash bed act like a beacon because they are visible from hundreds of meters away. Other plants bloom in such profusion that no pollinator would pass without a closer look.”  At next year’s Autumn Equinox squash harvest, I’ll find out if flowers made the difference.  In the meantime, we’ll enjoy meals from this year’s harvest.