We have over the years tried a number of different ways to get those early broad beans, from autumn sowing to applying heat, planting in plugs etc etc.
This year we have been a little more scientific, with 3 methods running concurrently. Planting times were set to be as early as possible within the positions.
Method 1 is straight outdoor sowing under fleece, with the beans planted late March and currently about 6 inches high with sturdy stems, showing all the right signs to becoming strong plants.
Method 2 is outdoor under a glass cold frame, with sowing late February. The stems are a little thinner but are about 12 inches high and looking good with supports probably needed. History tells us that this method might flower slightly earlier than method 1, but there will be little difference in cropping time.
Method 3 is in our polytunnel, with sowing late January. The plants are strong, nearly 24 inches high, in flower, and with some flowers pollinated and already showing small pods.
This is our third year with the polytunnel and it continues to bring great benefits. It gives us salad leaves through the winter and its size seems to balance out temperatures, so that we can start plants off weeks earier than even a greenhouse can achieve. We will be eating broad beans from here within 4 week or so. I have also planted peas in amongst the beans for a second crop.
It goes without saying that I am a fan of the polytunnel.