Posted: 01/05/2014 at 07:37
I often sow my runner beans direct into the soil and if the weather is reasonable they seem to catch up with those that are started off inside.
As Welshonion says, you might need to strengthen your support, perhaps with some canes braced at an angle at the ends, when the beans get to the top - they can be very heavy and catch the wind. But don't worry, that won't be difficult to do.
Let us know how you get on