to grow or not to grow in polytunnel

[doopers24]

I planted lots of flower seeds and some veg including broad beans in polytunnel in February, I have to say not a lot happened, got some come up but not a lot, does anyone know if it would be better to grow seeds in a coldframe or glass greenhouse, I was wondering it might have been because they didn't get enough light or heat? be great if someone could help.