Sweet pea seedlings - need some advice

I've never grown sweet peas before but thought I'd give them a go this year. I know it's a little "late" to plant seeds but nothing ventured, nothing gained. I only planted the seeds 11 days ago and they are growing extremely well, the tallest is probably 3 inches in height already. They're not leggy though, the leaves are coming on and I have them on a fairly cool window ledge (indoors).

I planted them into toilet roll holders and stood each holder in a compartment within a large seed tray.

And this is the "problem" - the roots are already coming out of the base of the toilet rolls. They do grow rather fast!

I intend to plant them outside soon anyway (just waiting for my canes to arrive), but as a stop-gap measure I lifted each holder and put another inch or so of compost in the bottom of the seed tray compartments. I'll just have to be careful that the main root tip doesn't break when I lift each one out.

So, in short - did I do the right thing? I had considered re-potting them but I don't have any suitable larger individual pots.

It's a learning process so I'd like to know the best approach for future sweet pea seed growing. Should I perhaps invest in some proper root trainers for example? Or should I just stick to toilet roll holders and not worry about roots protruding from the base after just 11 days?

Thanks

 

They could've been planted out (assuming hardened off) in advance of adding canes, using short lengths of split canes or small scraps of twiggy stuff to hold them off the ground until canes are pushed in beside them.

 

Thanks for the advice folks, duly noted.