Q Why aren't my runner beans flowering?
A Sometimes you just need to be patient, as runner beans often take quite a while to start flowering. Spells of hot, dry weather can cause the buds to drop off, as can a lack of pollinators. Birds sometimes pick off the buds, too.

Caption: Flowers are essential for a good crop of runner beans

Q How can encourage my runner beans to flower?
A Grow a runner-bean variety that was bred by crossing it with a French bean – for example, ‘Moonlight’ – as these are far more reliable croppers. Choose a site that is sheltered from wind so that pollinators can do their work. To help keep the soil moist, dig in lots of garden compost before planting then mulch around the plants. In dry weather, give them a thorough soak. If you suspect birds are a problem, the best solution is to grow your beans in a fruit cage. 

Runner beans become stressed if night-time temperatures exceed 15C with uncomfortable high humidity for more than two consecutive nights. The plants often abort their flowers under these circumstances. Cooler nights are needed for flower setting and the production of straight pods. Many gardeners try to lower the temperature and humidity by hosing all over the plants during the late evening but unfortunately only a change in the weather will help.