Underground greenhouse for citrus in BC

Hello Permies!

I recently became involved with a project that has the lofty goal of growing citrus fruit in an underground greenhouse in the interior of BC.
We are considering several sites for the placement of the green house and the issue of winter sun has come up.

There is concern that inadequate sun during the winter will hinder growth, but by my estimation, the growth cycle of the trees would not be affected as the winter sun is not strong
enough to support much growth. I am unfamiliar with the growth cycles of citrus... So long as the temperature of the greenhouse can be maintained, is the amount of winter sun going
to play a major role in growth? Any advice or shared experience would be greatly appreciated! Thanks!

Cozzy Bones : think in-ground rather than under ground, and be aware that you will have to have an air lock configuration, and a ''Cold well'' (For the cold air to fall into)
ether in the air lock or just inside the greenhouse proper, also the orientation of the green house and landscaping to help create a micro-climate will be work and money
well spent !

Paul Wheaton our host here at Permies has a long term goal, of growing a lemon tree out doors, using landscaping to create a micro climate, and the theory says you can
make the tree survive, the number of years out of 10 that you will get Flowers, pollinated flowers, set blossoms, and growing fruit, will depend on the fates as much as the
hand of man ! On the plus side nether one of you should have to worry about about airborne spores drifting in from your neighbors

I would pay close attention to how often in winter you are going in and out the door, during B.C. cold snaps frequent trips into your green house to feed fire wood into a
pot-bellied stove could vent as much energy as your stove can crank out ! Good Luck ! For The Good of the Crafts Big AL !

I have been growing citrus in Portland, Oregon, for 30 years or so. I take the potted trees in and out. My first was a Bearss lime, and this is probably best to start with. The second was a grapefruit, which is more bulky but gives beautiful blossoms in the winter. I would not feel good trying to make them stay in year round. I top-dress with coffee grounds, which worms like, and they come in some times. A challenge is aeration. If they go out, sow bugs and worms do that, and bees pollinate, which is better than a human doing it with a paint brush. I have a number of friends who have tried it and not kept up with them, but I enjoy these trees so much.