I purchased a gorgeous 3-foot potted Meyer Lemon Tree from a local greenhouse in the spring and it thrived all summer outside on our sunny deck: it was full of glossy leaves and even gave us 3, good-sized lemons! Since we live in Edmonton Alberta (Canada), I brought it inside once the weather began to turn. I tried to acclimatize the tree gradually but clearly did something wrong because almost overnight it lost almost every leaf (only a dozen leaves remained but these are still green and glossy). I was very worried that I’d killed it but kept it at our sunniest window, heated the roots (its drip-tray covers our forced-air register), continued to fertilize (with a 20-20-20 product) and water when the soil dried out. It soon filled out with dozens and dozens of blooms – it was so full of flowers you couldn’t even see the branches! And the smell…..! I’m guessing this means our tree was happy…(?) but now that the blooms are finished I’m not seeing any lemons, nor am I seeing any new leaves. Should I be concerned? Should I do anything differently to encourage leaf production? I don’t really mind if we don’t get any fruit but I don’t want the tree to die before I can put it back outside next year.
Keeping the roots warm is a good idea but I wonder if the register, though closed, is still releasing enough heat to create a draft. Also, the heat is not always on so there could still be times when the roots are cold. A combination of cold roots and high light level could explain the leaf loss. As an alternative a string of small incandescent lights could be wrapped around the container to provide constant heat throughout. Speaking of drafts, might there be a cold one coming from the window? A profuse bloom is not necessarily a good sign; quite the contrary it can be the plant's reaction to stress. From your description it sounds like leaf loss preceded the bloom. For the time being I would stop fertilizing and water only when the soil has had a chance to dry; the tree will need very little moisture, having lost most of its leaves. You could also over-winter the tree by keeping it in a cool, dark room where the temperature will be below 13C but above freezing.
Thanks so much for your reply. Unfortunately, we live in a very small house so there aren't many spots that are away from drafts - the spot we have the Lemon Tree in is the most protected, albeit sunniest, place in our home. Yes, it is by a window but gets no cold air. I do have one option - our basement laundry room is very cool (likely not much warmer than 16 degrees) but it is also very, very sunny. All other parts of our house are tied into our central air system and get up to 22 degrees...and our garage, although dark, is unheated so well below freezing in winter. Should I opt for a cool, sunny spot downstairs or leave it upstairs where the temperatures are warmer and equally sunny? Would you recommend a different fertilizer (I've been using a 20-20-20)? Do you advise a moisture gauge for the root system? Thanks again for your feedback!
It is at temperatures below 13C that a citrus tree goes into dormancy. Since that is not the case in the basement you'd be better off to leave the tree where it is. A fertilizer with a 5-1-3 NPK ratio is recommended for containerized citrus. Two that are readily available are Miracle Gro 24-8-16 and Plant-Prod 30-10-10. Be sure micronutrients are included. I prefer to go by the relative weight of a container to figure out whether it needs to be watered rather than using a moisture gauge. Is the tree getting direct light behind the window? Could the leaf loss be high leaf temperature? To change things up you might try using a light window covering/shade or pulling the plant back further away from the window.
I too grow Meyer lemons in pots. Something else that might be preventing the tree from re-leafing is spider mites, which citrus is susceptible to, especially in dry winter indoor air. If the blooms are done, give the poor thing a spray with insecticidal soap. They also love a good lukewarm shower (I used to drag mine into the stand-up shower until it outgrew its pot and now it's too heavy to drag very far!), which you can do when it's time to water and has the added benefits of washing spider mites off and increasing the humidity around the plant. I try to duplicate Florida for my citrus -- lots of sun and humidity, and deep watering only when dry. The latter works best if you've switched the growing medium out to a gritty, fast-draining potting mix. PS. The next time your Meyer lemon flowers, use a Q tip to transfer the yellow (ripe) pollen from the male flowers (no stamens) to the female ones (with stamens). The stamen will turn yellow and voila, you'll get a lemon! Don't do too many at a time, though, or some will drop off because they can't sustain. My 3' plant currently has four almost ripe and three or four coming along, which seems about what it can handle. Good luck! keke