Lots of flowers, no fruit

[languedoiseau]

Dear chile enthusiasts,

I'm growing two trinidad chilis. I've planted them in the beginning of last spring. They have produced hundreds and hundreds of flowers, but all in all I picked... 3 fruit... that's not much.
The flowers appear, open, and then fall down - stem and petals, everything separates from the main stem. There's no trace of an embryo of fruit.
The conditions I grow those chiles are the following:

. they are potted
. they've never been outside - no garden, no terrace, no window sill
. they sit behind a window where they get as much sun as possible in the flat. In summer, it's very sunny and hot there.
. I don't water much - every second day in summer, when the heat dries the ground very quickly, twice per week in winter. The top layer of ground is always a little dry.
. I've never fertilised, but I use potground that contains slow-release fertiliser - in principle there should be enough for a few months, right? The potground I use is very standard.
. There seem to be no sign of vermin. The leaves look normal - apart from the fact that one plant almost died while I was in holidays due to lack of water. I managed to revive it against all hopes, but the leaves still look a bit crinkled. But anyway, this plant produces more flowers than the other, and everything looks normal apart from that.

I'd like to add new members to my tiny family, but first I want to get a few fruit... 3 in 8 months, that's not much, and it's a pity to see all those flowers falling...
Have you got any idea?

Thanks a lot!

[varg]

On the one hand it could be abundance of nitrogen.
On the other hand the lack of air circulation may cause such things. Pollen of some C.chinense cultivars couldn't be formed normally without proper air circulation/ If you want to solve this problem just use a fan.

[languedoiseau]

Thanks a lot for your reply!
Therefore I'll try two things:

1. use a fan to shake the plants a little, and if that doesn't work
2. use pot ground which doesn't contain fertiliser.

The plants are still going strong and blooming, even now that days are short and grey, I hope to get fruit one day!