Petunia

The petunia (Petunia × hybrida) is one of the most popular annuals for window boxes and hanging baskets, thanks to its lavish, long-lasting flowering from spring until the first frosts. Plant it outside only after the last frosts, usually in May, in a sunny spot — less sun means noticeably weaker flowering. It needs regular watering and frequent feeding, as it quickly exhausts the nutrients in a container, but it will not tolerate waterlogged roots. Pinch off spent blooms regularly so the plant does not set seed and keeps flowering profusely. It comes in many colours, including trailing varieties perfect for balcony railings.