In what size container do you have the lemon tree? Just curious. I’ve got mine in those black container thingies that contain feed for cows/etc. They’re about 30gal. We move them in and out via movers dolly twice a year. I also make sure to water my tree until water is pouring out the drain holes every single day without fail. Twice a day if it’s been hot/dry/windy. I also use this:
https://www.walmart.com/ip/Espoma-Organic-Citrus-tone-Plant-Food-27-lbs/106661356
My lemon trees aren’t very big right now but have 5 or 6 on them. I have 2 larger trees and one that I started from a cutting last year that’s about 1’ tall right now.
I use that fertilizer stirred into the top 1” or so of soil. Probably once a week, maybe 10d or 2w.
I have a lime tree that’s about 6’ tall right now and absolutely loaded. Probably 60+ limes on there. I water it twice a day regardless since it’s got so much fruit on there.
YMMV of course. I’m jonesing for a mandarin/tangerine tree and a grapefruit tree.
My lemon is in an odd pot hubby found. There’s a place in the city where hubby sometimes works that people recycle pots, you leave what you don’t want in this bin in a parking lot and you take what you want. He checks it a couple times a year for me and brings home any big pots, clay or ceramic pots. My lemon is in one he found that’s tall and about 18” in diameter.
Our deck faces southwest and its right off a glassed in sunroom so it’s stayed on the deck in summer and in the sunroom in winter. This year the trouble has been constant wind. There is no place outdoors to protect it from wind as we are right on top of the tallest hill in the area. Even moving it around the house doesn’t get it out of wind. It’s spent much of this spring/summer back in the sunroom. It has direct sunlight this way and has sprouted new growth but I also have to be careful of leaving it in here because if we leave, shut the windows and doors the heat cooks the plants. Generally the only thing safe to leave inside with the place closed up and locked down is cactus. I had a greenhouse until 2 years ago but it finally fell apart. Hubby is actively using his Craigslist addiction to find materials to build a more sturdy greenhouse.
Outdoors I keep the tree atop another decorative container with no drainage that’s filled with rocks. It gets watered morning and in the heat of the afternoon and sits on rocks with water below for evaporative humidity. Indoors it’s in much the same setup on top of an old birdbath. I use the same fertilizer you listed with a bi-weekly foliar feeding of a compost tea spray. We’ve upped the misters around here for everything this year but the hot dry wind has taken a toll. Fortunately we’ve had a little rain 3 days in a row now so everything has perked up nicely for now but no more rain in the foreseeable forecast.