A herbaceous perennial plant is defined as a non-woody plant which usually dies back to ground level and grows again from the rootstock each year.
These plants are sold in two forms:
- Herbaceous Plants (specified separately)
- Herbaceous Bulbs (Perennating/storage organs, corms or tubers)
Some bulbous plants (Crocosmia spp., Dierama spp., Arum spp.) are usually supplied as Herbaceous Plants (specified separately). Other bulbous plants (e.g. Cyclamen spp., Galanthus spp.) may be sold as dry bulbs or corms but establish better if planted ‘in the green’ or as pot grown plants. All bulbs can be grown under contract in pots and supplied as growing plants, if so specified.
The NPS further classifies herbaceous bulbs by:
Each plant must be specified by giving its full BOTANICAL name. For full details of the specification terms used in naming plants see Trees.
The main specification for bulbs and corms is circumference in cm. The circumference is defined as “the largest circumference of the bulb, corm or tuber when measured perpendicular to the axis of the stem after having been lifted and air dried.”
Standards have been determined, indicating a minimum circumference, and larger grades, which are to be expected in cultivation. I t is anticipated that bulbs, corms and rhizomes of these measures would flower in their first season planted in open ground.
The minimum circumference and the grades depend on the individual species/cvs.
The bulbs, corms or tubers must be firm and not in any way shrivelled, particularly genus Lilium bulbs. They must also be visually free of pests and diseases, free of soil and any damage which might adversely their growth. Although there are no standards, it is possible to specify ‘virus free’ bulbs which can be more vigorous than those which are infected.