Pollinating in a high tunnel?

Fruitnut or other high tunnel or greenhouse growers how have you handled pollination? Bumblebees? Leaving doors open for native pollinators to enter the structure?

I am going to put up some type of structure before next spring, this year’s weather has been the final straw.

Yes bumblebees work well. It’s about $160 for a class C hive witch gives about 5 wks of pollination. I tried to have the bees arrive soon after the first open flowers Five wks was enough pollination time.

I’ve also hand pollinated some with decent results but it’s very tedious.

In my hot dry greenhouse a light spray of water on the trees several times a day during bloom helps set on peaches and nectarines. I think it helps spread of the pollen and perhaps helps it stick to the stigma.


I plant flowers near the openings to encourage pollinating insects to come in.
And try to keep something blooming all the time.
This spring has been cool, so I have had it closed up mostly.
I believe the syrphid flys ( hover flys ) have pollinated my strawberrys.
As I see lots of them visiting the flowers, and have not seen bumble bees in there yet.
In the summer enough insects come in from outside that pollination is not a problem. When it’s cold and closed up, this can be an issue.
I tried razing bumble bees with little success last year.
I did not buy a bumble bee hive
But rather tryed to raise queens and start a hive, a real project ,
Not a lot of luck, did get one laying.

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How about luck with pollinators in a high tunnel in relatively cold temperatures? I’ll be planting some strawberries in an unheated greenhouse, though the bed does have soil warming cables, black plastic, and a row cover low tunnel over top. The plants should start blooming in early-mid March, still chilly up here.

Anyone have experience with this situation? Has anyone ever put a heating pad under a bumblebee colony or under their supplemental food supply?

I asked around a bit and here are the answers I received from various field experts in response to my question above (in case anyone else is curious)–

"Very interesting question. We currently have some bumble bees doing just fine in a greenhouse in Ithaca, but it’s heated. I don’t have any experience trying to get them to forage in unheated greenhouses in March, so I can’t give you odds on whether it would work or not. That said, bumble bees will forage at lower temperatures than most other bees, and taking measures like you suggest below (warming the sugar bladder under the hive, etc) might get them to be more adventurous and head out to flowers in a cold March greenhouse. "

"Yes, bumble bees do seem to be the best fit for GH production-effective, affordable and easy to manage. I don’t know the size of your greenhouse, but I’ll guess you’ll want the smallest commercial hive available (otherwise there can be too many flower visits). Koppert and Biobest are the common suppliers.

Temperature-if it is warm enough for strawberries to flower, I’ll venture that it is warm enough for bumble bees to pollinate.

There are growers who’ve provided sugar water, but often the hive comes with nectar already. It will be important to provide plenty of pollen (flowers) once the hive arrives, so timing this with the supplier is important."

“Bumblebees are much more tolerant to cold temperatures than honeybees, so I would agree with that if the GH is warm enough for the strawberries to bloom, the bees should be active. Bumblebees are also less aggressive than honeybees and are the preferred pollinator for GH berries. The only place honeybees are used is California (where bumbles are considered invasive and outlawed).”

Not sure about that last statement, she must have meant in greenhouses but I’m pretty sure people outside of CA have tried honeybees in GHs too… Anyway, that’s enough info for me to give it a whirl if I can find a small and reasonably priced bumblebee colony.

I’m planning to give mason bees a try in my greenhouse this spring, at least during the 10 days I’ll be out of town around peak bloom (I’ll be hand pollinating the rest of the time). Has anyone tried mason bees inside a greenhouse or high tunnel?

Once the avocados are in full bloom I think they’ll have plenty of food, but I’m not sure if they’ll all just try to escape? The seller has this page about it that says they might orient toward UV sources since the polycarbonate is UV filtered, which means air intakes and exhaust:

I can try to cover all those potential escape areas with mosquito screen, but probably can’t get every last crevice around doors and vents.


Got my first shipment of 20 mason bees today, three had already emerged when I opened the tube! Since the avocados are barely starting to bloom now, I am leaving the greenhouse doors open for now so the bees can leave if they want. I’ll be getting another batch in a few weeks and those will be the ones I trap inside, along with any from this batch that are slower to emerge.