Pollinating Cucurbits

In my own garden, I'm just starting to see squash and cucumber blossoms on my plants.  I'm also starting to get emailed questions that suggest that folks are starting to see signs of pollen limitation on their own squash, zucchini, melons and cucumbers.  This is normal for the first blossoms of the year.  Cooler temperatures may mean that pollinators are less active.  Or, not having many blossoms in bloom may mean that the pollinators that are active aren't likely to find your flowering cucurbits. [Insert gratuitous plug for my own research, in an attempt to draw folks to a paper that few will ever read, otherwise.]

Fertilized zucchini (bottom) and unfertilized zucchini (top). Plants will drop unfertilized fruit, rather than wasting resources on their continued development.

Fertilized zucchini (bottom) and unfertilized zucchini (top).  Note how the seeds are fully developed in the fertilized zucchini, and the lack of evidence of seed development in the unfertilized zucchini.

Once cucurbit ovules are fertilized, seeds will develop, and the flesh of the plant will expand around the seeds.  When curcubit blossoms don't receive adequate pollination, rather than waste resources on developing unfertilized fruit, the plant aborts fruit development.  If your squash, zucchini or cucumbers are basically withering on the vine, shortly after the flower drops off of the fruit, you likely have a pollination issue.

To get around this issue, especially early on in the season, you can pollinate your own zucchini, squash, cucumber or melon blossoms.  Last year, I shot a few videos with my cell phone to demonstrate.  These videos were shot early in the morning, before coffee and enthusiasm  had made their way into my body.  Nonetheless, they might prove useful, if you're looking to pollinate your own cucurbits this year.  The videos are split into three parts:  (1) learning to distinguish male from female blossoms; (2) preparing a male blossom to pollinate, and (3) pollinating the female blossom.

Part 1:  Learning to distinguish male from female blossoms.


Distinguishing male from female zucchini blossoms. from Gail Langellotto on Vimeo.
Part 2:  Preparing a male blossom to pollinate.


Preparing the Male Flower to Pollinate from Gail Langellotto on Vimeo.

Part 3:  Pollinating the female blossom.


Pollinating Zucchini by Hand from Gail Langellotto on Vimeo.