posted 5 years ago
Citrus in general do not like wet feet, so if it's waterlogged and the soil doesn't drain well, that's going to be a problem. In fact, they don't like to be sprayed much in general. If you've got it somewhere where sprinklers hit it, you'll want to move it.
Think of where citrus trees commonly grow: places like Florida, where the sandy soil drains quickly and freely. If your potting mix is too heavy, you'll want to get something more suited for citrus. Most home centers have a cactus mix.
Citrus are heavy feeders. Are you giving it regular nitrogen? I'd suggest urine -- pee in your watering can at least once every week or two, and use that "charged" water to give your tree a drink.
Lemons require both full sun, and cool shade (over the roots). Keep their heads in the sun and their feet in the shade --- the standard line for just about any fruit tree. Is your pot large enough? If the hot summer sun is hitting the pot and its raising the soil temperature, you need to: A) shield the pot from direct sunlight, B) get a larger pot so that the roots aren't getting baked on hot days. An unshielded pot can get upwards of 120 degrees or even more on a hot day. That'll shock the crap out of any plant, sun loving or not.
If you've grown the plant from a seed, it's very likely that it may not actually produce a lemon. 100% of commercial citrus tree have been grafted. In all my experience and visiting both commercial operations as well as back-yard gardeners, I know of no wild citrus that was grown from seed that is actually a productive tree. If your tree actually does produce fruit, I'd be very curious if its even eatable. You'd do yourself a favor to purchase a tree from a nursery that is grafted with A) a strong rootstock appropriate for your area, and B) a known fruiting stock that will produce a recognized lemon variety (Eureka, Meyer, etc.)
If your interest is just the novelty of growing a tree from seed, then more power to ya. Get it into some well-draining soil, don't over water, feed it, and keep its head in the sun and feet in the shade.
Good luck.
"The rule of no realm is mine. But all worthy things that are in peril as the world now stands, these are my care. And for my part, I shall not wholly fail in my task if anything that passes through this night can still grow fairer or bear fruit and flower again in days to come. For I too am a steward. Did you not know?" Gandolf