| 2. Tender Perennial.|
Also known as half-hardy perennials, as they all need protection from frost. This group includes most greenhouse or house plants, and winter dormant plants such as dahlias.
3. Hardy Biennial.
Many root vegetables belong in this group, as they are sown one year and flower the next. Some can be forced to flower the same year, but usually they will produce seed to allow a continuous supply of yearly flowers.
4. Hardy Annual.
These can withstand frost, but usually grow, flower and die all in one year. As they can withstand cold temperatures, some can be sown in autumn to produce flowers the following summer. They make excellent container plants, and can supplement herbaceous perennials and shrubs.
5. Tender Annual.
If these plants are frosted, they will die, so must be planted out when the last of the frosts occur, which for the UK is around the middle of May. They can be grown under glass before this, so when planted out they will have a head start. Alternatively they can be sown outside in early May. As soon as the Autumn frosts arrive, they will soon die.
So now you know!