I am not an expert but I doubt it. Double poly tunnels are can keep in a decent amount of heat during the day, and at night most plants can take a decent dose of cold provided it's not frost. However I'm not an expert.

But is spending irreplaceable fossil fuel energy on what are basically short-lived ornaments rational? I'd say no.

It’s possible to run a greenhouse with green energy. It’s not possible to do that with jet airplanes.

It's likely the place where that energy is expended is not being taken into account. Injecting water vapour and combustion products from burning jet fuel high in the sky is probably a lot more harmful than just the amount of energy is being consumed.

The skies in summer here are criss-crossed with dispersed contrails. It might help a little with global warming by increasing the reflectance of the atmosphere but it's sure ugly.

If energy was sufficiently expensive, we would just build greenhouses like so: https://www.lowtechmagazine.com/2015/12/reinventing-the-gree...

It seems employing Western Europeans to plant and pick flowers in Western Europe would mean expensive flowers, and they've apparently calculated it's cheaper to let Kenyans plant, pick, ship the flowers to big Boeings, for pilots to burn fuel flying the Boeings to the Netherlands, and for the flowers to be distributed around W. Europe (and apparently USA) that way.

It' the same with people screaming why their country doesn't have their own PPE manufacturers; because in non-crisis times, the hospitals would buy from the lowest bidder, and those would be manufacturers with cheap developing country labor..

Would it not be possible to build efficient greenhouses and save costs on heating systems?

Surely solar power could help.

Source?