You can totally grow lemon, orange and lime trees here on the wet, west coast of Canada, both in pots and in the ground.
Our weather here on the west coast tends to be fairly mild in both winter and summer, but we can get snow and we do get cold snaps. Citrus trees do not tolerate freezing temperatures, they must be kept above 0°C. So how then to best protect them during a frosty cold snap?
Contrary to popular belief, the answer is not to bring them indoors for the winter months, unless you have a cool sunroom or 'conservatory'. Citrus do not thrive (and may not survive) indoors, as our homes tend to be much too hot, much too dry, and not near bright enough.
GENERAL WINTER CARE - CITRUS IN POTS
All citrus trees like humidity and cool-ish temps, ideally between 5° - 12°C with 7 to 8 hours of bright light in winter time.
I keep my citrus trees in a greenhouse during the winter months. As the heating is super expensive, I keep it on the low end of the scale, at +5°C from November through till March. They love it, the cool, humid greenhouse keeps them flowering and fruiting all winter long.
When I say that I set it at +5, that means the lowest temperature that it will go to. The temperature in the greenhouse will be higher in the daytime, usually, and on sunny days, of course, but it will not dip lower than +5. Also, even if it were to rise to +30 during the day, it is not the same as +18 inside the house. The greenhouse is always humid and airy, not tightly sealed as our homes. If our homes were moist like the greenhouse, we would have algae and mould growing everywhere.
BUT.. How to over winter lemons, limes, and oranges without a bright sunroom or a heated greenhouse?
Potted up trees are easy to move around from spot to spot, as needed. If your trees are large and the pots are heavy, you will want to consider how best to protect them before placing them in their winter home. While winter temps are above 0°C, leave them outside rather than inside the house … like on the front porch or doorstep, under the eaves, in an unheated hoop house or greenhouse, under some kind of roof or overhang to protect them from the winter rains. They do not like to sit in wet soil.
A shed or garage is not a good idea as it would be too dark, unless you supplement with a grow light. Close to the house on the south or west side to soak up some of the heat from the siding is a great idea.
KEEPING CITRUS WARM DURING A COLD SNAP
What to do with your tree if a cold snap threatens?
Bring it in - If it is a smaller pot, simply bring it in for the night, or for as long as the cold snap lasts, then pop it back out again when temps are above 3°C. It can go in for the night and out for the day all winter long, if you have the patience for that.
Unheated greenhouse or hoop house - Run an extension cord to your greenhouse. Inside the greenhouse have a small heater, or a light stand with a couple of 100 watt lightbulbs in it, or a strand of Christmas lights around each tree. Plug in when night time temps are going to dip lower than 2°C.
On the porch, wrapped in Christmas lights. - Wrap your trees in old-fashioned Christmas lights, not LED as they emit no heat. Plug them in during a cold snap and wrap with a frost blanket (white fabric) to retain the heat by the tree.
Build a shelter - I know people who have built a 3 sided wood framed little ‘greenhouse’ that fits in snug by the house. They plug in the Christmas lights and fit the little greenhouse around the tree, snug against the wall of the house. The wooden (or pvc) frame is covered with either poly or the white frost fabric. With the protection of the inexpensive ‘greenhouse’ and the lights turned on, the tree will stay cozy and warm without great cost.
If you really feel that you have no options, the most tolerant citrus to bring indoors for the winter are Meyer’s lemons, Calamondin oranges, and kumquats. Keep away from drafty locations, heaters and vents, place in a bright window, in a cool room, on a pebble tray of water, mist often.
GROWING LEMONS OR LIMES OUTDOORS IN WINTER
Sour or acidic citrus, like lemons and limes are hardier, so can be grown in the ground here in our zone 7 and 8 gardens, with protection. Sweeter citrus, like oranges, need to go into pots as they require warmer temps to thrive.
Grow your citrus on the southern or southwestern side of the house, in a sheltered spot. They do not like windy areas, so make sure to not plant in a wind tunnel. Citrus trees do not like wet feet, plant in well draining soil or build a small raised bed for your tree to provide great drainage.
Plant under the eaves or build an overhang, as in the picture above, to protect the tree from our winter rains and to soak up heat from the side of the house. Wrap your tree in Christmas lights, the old fashioned kind, not LED as they emit no heat. Plug in lights during a cold snap and cover with homemade greenhouse as mentioned above for the potted plants, or attach frost blankets to the overhang, secure the bottom with rocks or weights of some kind, thus creating a nice cocoon for your lemon or lime.
For more about general citrus needs and care, please see Part One HERE.
Happy Gardening & Citrus Growing