Planted lemon trees from seed need some advice please.

Hi guys I'm new I'm from the UK and I had a go at planting lemon seeds I didn't expect them to grow but they did, I can't remember when I planted them but they are more then 6 months old, they haven't really grown very much and lost a lot of the lower leafs and grow new ones at the top some of the leaves have some yellowing around the edges. I was just wondering what if anything I'm doing wrong or not doing? They have been grown indoors close to a window but didn't put them right in the window as I thought the sun might burn them. Thanks

I did the same thing, and now I regret it. Now I've got two small lemon trees, growing in small buckets after I've potted them up twice. Last winter I brought them inside and kept them in a sunny window, but sheesh, if I have to keep potting them up into larger pots, I won't be able to carry them. And they're thorny and taking up more space every year. I'm tempted to just leave them outside to freeze. Not sure what to do with them, otherwise...

Now that they're established, you might wish to keep them a bit drier than other plants.  Obviously, don't starve them of water, but they can stand to dry out a bit between watering.

The yellowing on the leaves may be exactly that: too much water.

Citrus are nitrogen pigs.  The best fertilizer is good old pee, slightly watered down (like, 10 to 1, water to pee).  

Yes, they like direct sunlight, but if you can keep the pots from getting direct sunl and thus, keep the roots cool, that will help them a lot.