My climber didn't flower

Q I have been waiting patiently for my cup and saucer vine to flower. The seeds were sown in April and plants grew well to about 3ft (90cm), but so far no buds. Should I give up now?

- Enid Gornall, Solihull, West Midlands

A The cup and saucer vine is such a good name for Cobaea scandens because held upright, each bell-shaped flower resembles a cup complete with rim sitting in a saucer formed by the calyx. The other name, cathedral bells, isn’t bad, either. This is a spectacular tendril climber originally from Mexico and South America which, although perennial in warmer climates, is grown in the UK as an annual. The large seeds germinate readily in warmth, but plants need a long growing season in order to reach a good flowering size before the weather turns cold.

I sow several seeds spaced well into a pot placed on a warm windowsill in February or March, and after germination I pot up each separately.

They are moved between house, porch and greenhouse for the best light and warmth, with the aim of potting on to 6in (15cm) pots and eventually into their final container a minimum of 12in (30cm) wide to stand under glass or on a patio.