Unlike woody plants, herbaceous plant stems do not add new growth each year. Many herbaceous plants die to the ground in winter, then grow new stems and leaves in Spring, but others stay evergreen. These may steadily increase in size by adding leaves and stems, but the stems do not gain hardness or grow in circumference with each new growing season. Herbs are not all herbaceous plants; some common herbs, such as lavender ( Lavandula sp.) and sage ( Salvia sp.), are technically shrubs because their woody stems increase in size each year when grown in climates in which they are winter-hardy.

Perennials Plants which continue to live and increase in the open for several years. Stems die down each season and grow up again from the crowns each Spring. Sow in greenhouse in March or in open in April, May or June

( plantes herbacées) plants with stems that are soft and not woody.