What s wrong with my lemon tree?
You have only provided a photo that shows a few browning, curling leaves, but no other details. I assume this is what concerns you about the plant.
There are a number of things to consider that may be affecting your lemon tree. See an earlier post on the Ask a Master Gardener website, Help me save my indoor lemon tree. This provides a number of tips for caring for your lemon tree, and explains what might be responsible for problems with the plant. You will see the importance of ensuring appropriate light, heat, soil, watering/humidity and fertilizer for the lemon tree. As well, insects could be a concern.
Another helpful post from the Ask a Master Gardener website is Lemon tree care. This provides good general information about proper care of the plant.
See also the University of California Cooperative Extension Extension Master Gardeners of Tulare-Kings Co. Common Ailments of Houseplants — you will see there are many reasons that leaves can turn brown and curl under. This would apply to your lemon tree, which is a houseplant in Ontario.
If, after you review the above links, you still have questions, please contact us again and provide lots of detail about the problem with your lemon tree.