Common. Normal for this time of year..:-) Sure you can keep it growing....Alot slower than in full sun, on sunny hot summer days.. It will constantly push out new growth from the top, unless you withdraw light all together. In fact if you used no lights at all, and just stuck them in a window, dependent on the winters light only, they would still grow a tad bit. The thing is, you will never get them to be fully leafed out, unless you provide 14 hours or more of full strength hot light and very warm conditions.. perfect conditions.. Hard to mimick in winter, especially in Canada. By nature they want to drop leaves at this time of year, especially in the fashion as you describe. Why even in Texas they are dropping leaves as you described.. My local nursery owner has a few, loosing leaves like crazy, like yours, in full sun, and in a hot greenhouse anyway..Don't fret.:-) Not to worry. They will not die, nor will they stop "growing" if you providing them some light. They will almost stop pushing leaves, and maybe not at all, if you withdraw all light and warmth. Your major concern should be your "watering" habits, and "root rot". Be careful, especially if your soil is not porous and free draining... At this time of year, your soil should not be wet more than a couple days at a time if in dormancy stage.. If so, you will loose them unless you are keeping them in active growth under warm lights and a warm enviroment..;-) Dormancy does not mean it is entirely asleep as some of our outdoor plants, such as perenials, it just means it is growing at a much SLOWER pace..Believe or not, they will still look for a drink, even in dormancy stage.. Just keep it alive, and the full strentgh of spring sun will bring it back to full leaves, and possibly flowers too..;-) Sorry about spelling. Time fleeted me and I had to leave fast..Hope this helped.;-)

First of all, yellowing and brown spots on the leaves of tomato plants can be a sign of different types of diseases, such as early blight, late blight, or septoria leaf spot. These diseases are usually caused by fungi that thrive in warm, humid environments and can spread rapidly in crowded, humid conditions. Based on your description, your tomato plants may be experiencing some type of fungal disease. Brown spots on the leaves, along with the white residue you mentioned, are common signs of fungal infection. Additionally, the presence of fruit flies on plants could also indicate fungal growth, as fruit flies are attracted to the sweet odor produced by fungi. To address the problem, it is important to take some steps to prevent further spread of the disease. First, you should remove all infected leaves and dispose of them in the trash, rather than composting them. This will prevent the spores from spreading to other plants. You may also consider applying a fungicide spray to the remaining leaves, especially if you see new spots appearing. As for leaf yellowing, this could be due to a variety of factors, including nutrient deficiencies, overwatering, or pests. You mentioned that your soil was low in nitrogen and phosphate, so applying organic fertilizer was a good next step. However, it can take a while for the plants to recover, as the yellowing can be the result of previous stressors. As for fruit flies, you may want to try some natural remedies, such as using sticky traps or applying a dish soap and water solution to the floor. These methods can help reduce the number of flies without the use of harmful chemicals. Finally, since you mentioned that you are a novice tomato gardener, it's always a good idea to do some research and educate yourself on common problems tomato plants can face. I would recommend visiting a website like https://thegardenplants.com/pests-diseases/leaf-problems/, which from what I've seen has quite a bit of information on leaf problems on various types of plants, although I don't think there is an article on tomatoes many of the solutions for these problems are useful regardless of the plant in question. I hope this information is useful to you and good luck with your tomato plants!

I dont know what it is but it looks like something to be concerned about to me. While you are waiting for answers here can you take some leaves back to the local nursery where you purchased?

This is the Ficus Carica forum. Edible figs. We are not experts on houseplants. If you want answers, go to the houseplant forum.