The terminology and techniques associated with horticulture can sometimes seem daunting if you don’t understand their meaning or how to utilise them for your benefit. There is no denying that an interest in horticulture can lead to a very detailed, skilled and highly specialised expertise. However, it is usually sufficient for most people’s needs if you can understand what’s written on the back of a seed packet or on the plant labels at the garden centre.
An area of terminology and technique commonly misunderstood is that which concerns a plants growing cycle and its relationship to the seasons. Below is an explanation of the meaning of Hardy Annual, Half Hardy Annual, Hardy Biennial, Hardy Perennial and Half Hardy Perennial.
A Hardy Annual is a plant that grows from seed and then blooms, drops it seed and dies all within one yearly cycle. Sunflowers and common opium poppies are examples of flowers grown as annuals. The seeds can be left where they fell and many of them will germinate and repeat the cycle the following year. Alternatively you can take control of the situation and sow new seeds in the spring; these seeds can either be from packets bought at the garden centre or from seeds harvested from last year’s flowers. These plants are called Hardy because the seeds can withstand the low temperatures associated with a UK winter. Indeed, some plants require a period of sub zero temperatures before they will obligingly germinate.
A Half Hardy Annual is a plant with the same life cycle characteristics as a Hardy Annual i.e. that it will bloom the first year from seed. However, they are called Half Hardy because neither the plant nor its seed are likely to survive the cold weather of a UK winter or indeed even late spring frosts. In most areas of the UK, you would need to sow them indoors and plant them outside after all threat of frost has past.
A Hardy Biennial is a plant that grows its leaves from seed during its first year, survives the winter, and then blooms the following summer. Once it has bloomed and dropped its seed, it dies. The whole cycle is then repeated the following year from its dropped seed. Foxgloves and Hollyhocks are good examples of Hardy Biennial plants.
A Hardy Perennial is a plant that lives for years although different plants have different life spans. For instance, Gaura is relatively short lived and needs perfect growing conditions to last 5 years although getting even one year from it is worthwhile for its captivating beauty. Some Hardy Perennials will be mature enough to bloom the first year from seed although others might take 2 or 3 years to fully get into their stride.
A Half Hardy Perennial is a perennial that’s grown as an annual because it will probably be killed by UK winter frosts. However, most will survive the winter if covered by horticultural fleece or moved into a protected space such as a hall or conservatory. Some frost free areas of the UK are able to grow Half Hardy Perennials as Hardy Perennials.
So, why is it necessary to have these various plant classifications? It’s because many of the plants available today have their origins in far flung corners of the world where cold, wet and dark winters don’t threaten to kill off the native flora. Nursing plants through the seasons is the price we pay for enjoying all those non native beauties.