Well, if you've read through this forum, you'll nearly all the successful container citrus folks use their own potting mix, as the stuff that comes out of a bag is just much too dense. Moisture meters like you have stuck in your pot can be notoriously inaccurate, and certainly will not tell you what's going on at the bottom of your pot, which can very well be a swamp, while the top of your soil can appear very dry. So, the first thing I would do is re-pot with either "Gritty Mix" or "511 Mix", both formulas can be found on this forum. Secondly, those same container growers prefer to use Dyna Gro Foliage Pro, mainly because it has the proper NPK ratio (it's not just about the N), plus all the micronutrients. Plus, the nitrogen is non-urea based, which is very important to prevent biuret build-up and leaf burn. You can use Foliage Pro either 1/2 strength or full strength with every watering. I would water, first, to moisten the roots, then fertilize. Never apply fertilizer to dry roots. Misting. Again. The myth that will not die. Citrus do not need high humidity. If this were so, they'd never survive in our S. California deserts, where there are still thousands of acres of commercial citrus groves. I have no idea where this myth got started. Yes, you citrus will always benefit from a hosing off, to remove house dust and discourage pests (all house plants will benefit from a hosing off), but you do not need to waste your time misting. And, I would leave your lights on longer. Meyer lemons are rather sensitive to light changes, so you'll see leaf drop, but, your tree looks to me like it's suffering more from compacted soil and lack of fertilizer, than lack of light. So, try fixing those two things, first. Fungus gnats can pop up in any soil, organic or not. They proliferate from too wet soils (which is my suspicion going on with your tree), so re-pot with better potting mix, and if they come back, you can use a product called, Gnatrol. It takes a couple of applications, but it is very effective. Another one of our forum members suggested another very effective product, just can't remember it off the top of my head. Hopefully, they'll post their product for you. Patty S.

You could just leave them in the clay pot and place those clay pots into decorative plastic containers with holes as I do. John's right, I found that many of my trees did not perform well when nights got too cold in clay. They never rotted because I use a porous mix but they most certainly had growth issues during all the months but summer unless they were kept in a very warm room which I do not when they came in. Root rot is not caused from too much moisture, but from a lack of oxygen to the root zone which most heavy compacted mixes will prevent. If you are growing that tree in a very good mix that allows oxygen exchange and helps keep the roots warmer on cold nights it should recover..If you want to see an even faster recovery during the shorter days, provide extra lights and warm conditions...) Root rot can not be caused by just cold, but poorly oxygenated roots combined with cold which is why many use use a porous mix or a small pot just big enough for the root ball when using a high quality bagged mix..

I'd say Silica is correct about the ratio of light to soil temperature. This is only meant to simplify the balance of the relationship between leaves and roots. Leaves use light to start the process of making food. The leaves will tell the roots that it needs all the ingredients of the photosynthesis "recipe" to finish making food. So in normal ideal outdoor conditions, the roots provide and send up water+nutrients needed to complete the food being made in the leaves. Imagine that to citrus roots 55F and lower is considered to be like frostbite to the roots. The roots cannot do anything when the soil is cooler than 55F. It cannot absorb water, it cannot function at all and so it basically sleeps to conserve its energy. However if the leaves are having a blast above the soil and getting a sunny Hawaii vacation thanks to strong indoor lighting, it will try to make food. The leaves cannot stop itself from reacting to light. When light hits the leaves and warms the leaves enough for it to function, the leaves will react to light no matter what and must start photosynthesis. But if the roots are too cold, it cannot send up the missing ingredients because it will be in hibernation. Eventually the leaves will lose moisture since it is in active mode. While the leaves are active and losing moisture, the roots are inactive and cannot send water up to hydrate the active leaves. Like running a marathon without any sustenance. The tree will sacrifice it's own leaves if it cannot provide itself the water or nutrients that is needed to continue with the process. Sorry if my post was long. I feel that it can be simple to understand if I try to compare it to thing we already understand. So to answer your question Mike, when the tree is getting plenty of sunlight that means leaf activity goes up and therefore root activity must also go up in order to keep the balance in their relationship. In order to make the root function as much as the leaves, temperatures of the soil surrounding the roots must increase. If root temperatures (and therefore root activity) cannot be increased because heating is too expensive, then the activity levels of both root and leaves must be in balance. Either the root or leaves will have to follow the other. If root activity cannot go up to parallel the leaves then inevitably is it up to the leaves to follow the roots footsteps and also be very inactive. That means reducing light levels to reduce leaf activity for the sake of matching the cold/inactive roots. I think of the leaves and roots as two parts of one living creature. It cannot live without one or their other. Both parts must follow each other because they are two halves of a whole. One is the pie crust and the other the pie filling. You cannot have a pie with a very thick crust but 2 teaspoons of filling and vice versa! It just wouldn't make any sense. You would have a very disfigured and unappetizing pie! They must both contribute the same amount to create a balanced and delicious food! I can get creative when I need to when it comes to explaining things so if this still wasn't easy to understand at all, feel free to let me know. I hope this helped anyone confused about the whole roots and leaves matter

Silica, thanks for the additional information. Are you assuming that I will be using the same fertilizer when you suggest that I flush the container every 5 or 6 months? If I switch fertilizers, can I avoid the flushing? If there is a fertilizer that would spare me from the flushing, can you suggest one? Would be very grateful for your feedback on this. Thank you. MyerMike, this is a great suggestion. While Lem Lem is in loamy soil now, I was thinking about transplanting her to a confirmed 5:1:1 mix so that the Houzz community and I would have a common reference point for future citrus challenges. If I made any bad judgement calls reference fertilizers or anything else, a 5:1:1 mix would allow me to "erase" the mistake and start anew. Is this along the lines of what you were thinking when you suggested a more porous mix? Sincerely, - John Coffey