‘Herbaceous perennial’ is one of the terms often used in gardening circles that can be puzzling to the beginner. In fact, herbaceous applies to any plant that does not form a persistent woody stem and covers annuals and biennials, but it is generally most closely associated with perennial plants.
A perennial may be defined as a plant whose top growth dies down in the autumn and begins to grow again in the following spring.
The terms ‘hardy’ and ‘half-hardy’ are also used in connection with herbaceous plants. As far as a perennial is concerned, ‘hardy’ means that it will survive the winter frost, whereas ‘half-hardy’ indicates that it will be damaged or killed by frost, but the degree of damage or outright fatality depend on the type of soil, since plants growing in wet conditions are more at risk, provided they are not moisture lovers. Such plants must therefore be given a sheltered position or be grown in a mild garden, or in well-drained soils. Even so, severe and/or prolonged frost will mostly result in death.
Broadly, the terms ‘herbaceous perennial’ and ‘hardy perennial’ are the same because almost all the plants in the former group are hardy.