Broad beans

Hi all,  my broad bean plants are currently looking a bit yellow rather than a nice green plant.  Does anyone have any ideas what could be causing this,  they were a nice green colour until I recently planted them out in to the soil about 3 weeks ago.  I am thinking the warm weather might have been the cause but now its cooled off a bit they are still yellow. 

It's more than likely to be a lack of nutrients and as Aunt Sally said feeding them with something like Miracle Gro should sort the problem. Also if it's been warm and windy they'll need plenty of water.