tomotaro germination doesn't work

[Syrck]

Hi,

This is my first experience germinating seeds. And i don't know where is the error because it doesn't work.

In 17 February i started with 5 tomotaro seeds. The seeds was in a room without light and 21 degrees Celsius for 10 days....and the seeds grow 6 cm in few days, but when i put outside, the light kill the plants.

In 2 of March, i began to germinate other 5 tomotaros seeds. In 4 days i put this seed in a window facing south. This plants was in the same conditions for 5 weeks , some days i put outside in the sun light directly but in 5 weeks only grow 2,3 cm and some leaves have withered..

This second time, i used mix hummus and sandstone for the soil, and constance 20 Celsius degrees, i take care that the moisture of the soil. I use a individual plastic containers for germination.

2 weeks ago i do it again with another 5 , Today, the plant height is 1.5 cm, but the impression is that this doesn't work....

I don't know where is the problem, maybe the light ? or the soil ? in the last weeks and i try to learn and read about it but i m feel stupid for this, because i know that it has a problem but i don't know how to solve it.

Someone can show me the way ? where is the problem ?

Thanks in advance and excuse my english,

Regards,

Kim