1 - There are several reasons cucumbers are not forming fruit and several potential solutions to the problem.
Yard and Garden August 3, 2013
If cucumbers have blooms but are not producing is there anything you can do to pollinate the blooms? If I need to hand pollinate should I use a cotton swab to transfer pollen from one flower to another? I also heard about a product for tomatoes that are not setting fruit. Do you know anything about that?
Cucumbers often produce male flowers at first and only later make the female flowers (flowers with a little cucumber behind the flower). This is true for squash, pumpkins, melons, and some other garden plants. Are there any female flowers present? If not, it will be a matter of waiting. Hand pollinating will not be successful.
If there are female blossoms there is a chance that there are no pollinators - bees, bumble bees, or native bees. If that is the case, then hand pollinating may be needed.
You can transfer pollen from male flowers to the female flowers either by using a male blossom you pick from the plant, a cotton swab, or small paint brush. Since the male blossom is not going to set fruit, that may be the best way to go. Do this early in the morning before 9 or 10 am. The pollen does not last very long, especially in the heat.
When the weather is hot, the pollen is killed by the heat and does not successfully pollinate the flowers. This may be a reason that the cucumber fruit are not setting. If it is staying hot at night, even hand pollination may not work; you will have to wait for some cooling.
There is a product called "Tomato and Blossom Set" that provides hormones to increase fruit set. You may be interested in trying it. I saw it advertised online by a major national mail order nursery and I would expect it to be available in other places, perhaps even local garden stores.
Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: firstname.lastname@example.org, office: 505-865-7340, ext. 113.
For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!