Asked July 10, 2017, 11:20 PM EDT

I have a newly built greenhouse a bit amateurish but its flourishing great except I can't get any pollination. I have lavender 40ft from my green house in front of my house that is swarming with bumblebees and honey bees but I can't get them to become attracted to my greenhouse. I do have the side plastic rolled up that allows for a 3'x8' opening and some fans on low to create air circulation for the hot days. Please let me know if you have some old school or new school tricks to help. FYI I do have an array of flowers as well integrated with my vegetables. I also propagated some lavender to see if that would help. Thank you very much!

Clackamas County Oregon

3 Responses

Thanks for your pollinator/greenhouse question. Some questions: can you send a photo of the greenhouse? What times do you leave the 'windows'/side panels left open? What hours are your fans on? Would you be able to roll back the sides of the greenhouse, so scents are widely available? Bees have remarkable scouting abilities. But, fans can send the scents they search for away from the plants with pollen and nectar. So they head elsewhere. While you are cooling the ambient temperature around the plants, you might be depriving the plants of a natural attractant capacity. There are no 'new school tricks.' Anything that works in nature is using 'old-school tricks.' As in 'Mother Nature' and 'let's try to duplicate what's been developing for millions of years.' Humans just try to learn what's evolved without our knowledge or intervention. There are no greenhouses (or electric fans) in nature. Think about limiting greenhouse use to extend the growing season--both before and after Ma Nature anticipated. Good luck!

Thank you for your response. I am leaving the side open all day right now because of high temps. The fans are on a thermostat that turns on when temps reach 75 degrees and usually run from 11am to 8ish. The setting for the fans is on low so it just pushes the air in three different directions.

Thanks for the pics. Nice 'home made' greenhouse! Your fans are going at exactly the time when bees are foraging. In researching a bit further, I found this article researching the ability of bumblebees to "use their fuzz to detect electric fields'" of flowers--that aren't moving (from our sensory perspective)! I know that fans are a low tech way to keep mosquitoes away (since the air movement dissipates the CO2 that we exhale.) I'm wondering if the air movement plus the bees' sensitivity to electric fields is what is keeping them out of your space.

With temperatures being what they are now, you shouldn't need a greenhouse to protect your plants from night time temperatures. If you're trying to keep non-pollinating insects from invading your vegetables, floating row covers would do that without air movement. Or just leave the fans off for a couple of weeks, and see if the bees visit.

BTW, many, many gardeners have noticed a general decline in the number of pollinators this year. It could be on account of the bitterly cold winter, hive mites or chemicals, but there may be increasingly more onerous ramifications of the trend.

Good luck!