Long stems, getting top heavy

Grow Cycle Seedling
1

A question from a fellow grower;

I think I might need to think about transplanting to bigger pots. The stems are long and spindley and they are getting top heavy at 5-6 cm. I’ve gently placed small supports to help them continue to grow stronger, I hope. Any advice on any of this?

2

Move lights closer !!!

3

Do you have an oscillating fan moving air around and causing movement for your plants. This strengthens the stem to provide support.