Flower types FAQs

Can you explain exactly what hardy annuals are?

Hardy annuals are plants that grow from seed, flower, and then die in one growing season, usually between spring and late autumn. They are referred to as hardy because they can be sown directly out-of-doors in the positions in which they are to flower. There are many hardy annuals listed in seed catalogues; they are very useful for making colourful summer beds and borders and for filling spaces among perennial (longer living) plants, such as shrubs.

What is the difference between a hardy annual and a half-hardy annual?

Hardy annuals can spend their entire life out-of-doors, but the half-hardy annuals will not germinate from seed in cold conditions. The latter, therefore, must be raised by sowing the seed in warm conditions (in a greenhouse, frame, or the home) and then gradually hardening them off as young plants before they are set outdoors in their flowering positions in bed or border. Many of the most popular bedding plants are half-hardy annuals.

What do seed catalogues mean by the term ‘biennial’?

Biennial plants are those that are raised from seed in one year for flowering the next. As most are hardy and are bedding plants, the seeds are sown outdoors during the first summer in a seedbed. The young plants are set in their flowering positions in autumn or the following spring, and after they have finished blooming in the autumn they are discarded. Some biennials, such as poppies (Papauer), honesty (Lunaria) and forget-me-not (Myosotis), will often seed themselves.

What are half-hardy perennials and how should they be looked after?

A half-hardy herbaceous perennial plant is one that will not stand cold conditions and needs some protection during the winter. Most of them are, in fact, treated as summer bedding plants. Typical garden flowers of this type are the pelargoniums (often wrongly called geraniums) and most florist’s chrysanthemums, which need to be dug up and kept in a frost-free place during the winter. Certain tuberous plants, such as dahlias and tuberous begonias, also require the same treatment.

Other herbaceous plants of doubtful hardiness in very exposed gardens can be protected in situ during the winter by covering them with straw or bracken held in place with twigs or wire netting.

Bear in mind that some plants are commonly termed hardy in mild areas, while these same plants will succumb to winter conditions in other, colder areas.

How does an herbaceous perennial differ from other perennials?

All plants that live for a long time, in the right climatic conditions, are called perennials. They include trees and shrubs as well as herbaceous perennials (sometimes known as hardy perennials). Trees and shrubs have woody stems, whereas herbaceous perennials do not. Most of the latter die down at the end of their flowering period, new top growth and flowers appearing the following season. The length of life of herbaceous perennials in the flower garden can vary from a few seasons to many years.

I often see the term ‘bulbous plants’ when reading about flowering plants. What does this mean?

Bulbous plants are those with fleshy roots, stems, or underground leaves which act as food-storage organs and from which the above-ground stems, leaves, and flowers arise. They are divided into four groups: bulbs, corms, rhizomes, and tubers. The groups are botanically different and in some cases require different growing techniques.

What is a rhizome and how should it be looked after?

A rhizome is a horizontally growing, fleshy, swollen stem that grows at the surface of the soil or ‘creeps’ underground. The most common hardy rhizomatous plants are the flag (border) iris and the lily-of-the-valley (Conualhria). Rhizomes produce the plant’s top growth from their upper portion and the roots from their base. The plants are easily propagated in autumn by lifting the rhizomes and cutting them into sections, so that each piece has buds on the upper surface and roots on the basal part. As regards conditions, lilies-of-the-valley grow in moist soil in partial shade, while irises usually prefer a drier, more sunny position.

When people talk about dahlia tubers are they referring to those unusually thick roots?

Yes, those roots are correctly called root tubers. They are fleshy food organs which provide foods for the stems, leaves, and flowers from upper surface ‘buds’. They also produce roots below to produce more food in order to create new tubers. Dahlia tubers are the ideal means of raising new plants each year, as they are easily divided; in doing this you must make sure that each tuber has at least one shoot bud attached to it. Because dahlias are half-hardy plants, they must be kept in a frost-free place during the winter and propagated in the spring.

Other common tuberous flowering plants are winter aconite (Eranthis), tuberous anemone, day lily (Hemerocallis), and herbaceous peony (Paeonia).

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