Post a photo, tell us how old it is, and what variety. It could be that your tree is just too young, or is underfed.

Or not self fertile. Which is rare for citrus.

Might be too cold to set? Where are you located? My container citruses bloomed several times since the fall with the sunny/cold weather we got (one week raining, nice and sunny the next, etc). My tango had 2 fruits that got to a dime size so I was hopeful but it fell off. Only the mature in-ground meyer's lemon tree set fruit reliably through out the year regardless of the weather. It's been sunny for a week after a month full of rain and all my container plants are waking up with new growth.

Pictures attached. You can see one with the existing small fruit too. Another with the blooms, and a couple more of the overall plant. Do note that any yellowish tinge you see is because of the lighting, the leaves are all a healthy green.

Got the plant one year ago, it is grafted, but I don't know how old. Don't think it would be more than two years old. It started blooming in November when temperatures started dipping to 15C at night or so. Kept blooming as temperatures touched 5-6C at night (with a bit of leaf drop though, recovered pretty quickly). Initial bloom all fruited but dropped off. Three were left, but I knocked off a couple accidentally.

After that, lots of blooms but no fruits. I have never fed it anything special. I use a mix of rich vermicompost, bonemeal and sterameal. Soil is very light and porous, drains from the bottom pretty quickly. There's a bit of cocopeat coir in there to keep the moisture in. It certainly seems to like the mix.

How old is the tree?

Got it 1 year ago, will be max 2 years. Grafted. Has fruited before but very few set (currently getting bigger).

We need some history. All the questions asked above are valid.

I've given all the history more than once, I don't know what else you want me to tell you.

Nothing, if it's too much trouble to tell us what we need to know then don't waste our time asking for help.

"Got the plant one year ago, it is grafted, but I don't know how old.
Don't think it would be more than two years old. It started blooming in
November when temperatures started dipping to 15C at night or so. Kept
blooming as temperatures touched 5-6C at night (with a bit of leaf drop
though, recovered pretty quickly). Initial bloom all fruited but dropped
off. Three were left, but I knocked off a couple accidentally.

After that, lots of blooms but no fruits. I have never fed it
anything special. I use a mix of rich vermicompost, bonemeal and
sterameal. Soil is very light and porous, drains from the bottom pretty
quickly. There's a bit of cocopeat coir in there to keep the moisture
in. It certainly seems to like the mix."

More info: I live in Delhi, India. It's not too cold, night temperatures are around 9-12 C and mostly 25-28 C during the day (and getting warmer every day). I do not know the variety. It's a generic lemon variety I got off eBay. As I mentioned before, it has set before.

Tushaar - did you give the history in a different thread? You started a new thread and ask a question with very little background. Several people ask for more information such as where are you located (zone, weather), how old is your tree, what is your fertlization regiment, and to post a picture. Indoors? Outdoors? If you gave these answers in another thread, you can't expect us to hunt for them. This is your thread, how much or little information you give is up to you. But if you start another thread in the future, chances are it might get ignored. People are trying to be helpful.

Got it, I apologize. I did add the info in the post with the pictures, but I wasn't aware what else you guys needed to know.

As mentioned, I do not fertilize except with vermicompost, sterameal and bonemeal. I grow it outdoors. in a balcony. I do not know the zone classification of the type used in the US, but summers are very hot and dry, there is monsoon and then winters with a minimum 4 degrees C temp. This remains for 45 days. This period passed around two weeks ago.

4 degrees c is way too cold, although you may have a microclimate on your balcony which could add a few degrees. I haven't gone below 7 degrees and I was very nervous about that even.

The cold might have caused a set back, but your tree looks pretty nice considering. I like the shape.

My trees are fairly young too and also set a lot of flowers and fruitlets and then drops them, it's normal. Probably a combo of the cold and age.

Also start using foliage pro for fertilizer and ditch the other stuff.

Hmm. A few flowers are going to open up very soon, and with night temperatures around 15C now, let's see what happens. I hope my plant doesn't become infertile suddenly.

Thank you for the compliments on the shape, I have actually pruned it during the winter to come out that way. Earlier, it was all growing to one side because the thickest branch was bent outward. Now, through select pruning and ensuring the sun is facing the side toward which I want it to grow, I am getting a somewhat "mini-tree" appearance.

It is not uncommon for young fruit trees to bloom and drop the flowers.

i have a peach, Apple and cherry that all bloomed. None of them will fruit this year.

Did you tell us the variety? I don't see that question answered. I'm thinking the plant is just not old enough yet. Now if it were a Meyer lemon or a kumquat, at that size it should probably bear. But it if were a grapefruit or orange, probably not.

Edit: I see you said 'generic lemon'. Not sure what that is exactly, but likely the plant is not large/old enough.

I have to tell you people that won't give us a clue as to what zone you are trying to grow these fruit in, or what it is planted in, and then you ask us to solve your problems. And when we ask you get so defensive There are multitudes of variables involved with growing good fruit year after year. Please try to cooperate. We are here only trying to help.

@tantanman I have subsequently provided all that information.

@Dave, unfortunately, do not know the variety. I know it is a lemon or acid lime (grafted) but no other info.

Night time temps below 15 C are too cold. Also try to keep the moisture even. Lemons are not able to respond to cold but the rootstock probably is and has an effect. Lemons and limes are more effected by moisture than temperature.

Many times repotting to a larger size will cause the plant to grow vegatatively and forego fruiting.

15 degrees Celsius is in no way too cold. If that were true lemons couldn't be grown in a vast majority of places they are today. A lot of people on this forum routinely push 0 degrees Celsius or 30 F.

I personally bring them inside at around 7 degrees C to be safe, but I am sure I have hit about 5 C before. It helps if they are under cover at least, and out of the risk of frost.

To reply to hobbyartisan and tantanman:

I do not think 15C and below is too cold, at least for citrus health, if not fruiting. All my citrus remained in the open for two weeks at 4C nighttime temperature without much issue. However, tantanman would be partly correct with respect to fruiting.

The latest blooms that opened a couple of days ago have all fruited, and night time temps are currently between 10-12 degrees. So definitely below 10C it seems the citrus will not fruit, but will remain healthy.

I also went back into my ebay history and I think I have citrus aurantiifola (key lime). This is a plant I procured from a state called Assam in India and was marketed as an "assam lemon". The main export of Assam is something called a "kagzi lime", which is a type of key lime.

Picture of fruiting below (the tiny green base of the flower - might have to look closely):

That seems to be the case pip. It was my first winter with this plant, so wasn't sure. I have around a dozen tiny fruit now, so I rest easy. Thank you.

The 15 C I was referring to was about fruiting. At bout 12 C many mandarins and trifoliate rootstocks begin shutting down. That stresses the fruiting part of the tree and sometimes causes death. I am not surprise if it dropped fruit and leaves when exposed to those lower temps at night. Trees are much better off it it gets cold and stays cold and does not try to grow or fruit. It's the yo-yoing that is making it try to grow in daytime and then the tender growth and freshly set fruit which are demanding more nutrients than the rootstock can deliver due to the cold night.

Some people withhold water from lemons and limes to keep them from cycling like that. They try to make them "sleep" through winter.