The term perennial is used to describe any long-lived plant that is non-woody (as shrubs and trees are). Herbaceous perennials are those that die down in the autumn and reap-pear in spring.

Please select a plant type for succesful growing and propagation details:

• Alchemilla
• Euphorbia
• Dicentra
• Achillea
• Oenothera
• Meconopsis
• Coreopsis
• Doronicum
• Papaver
• Verbena
• Tropaeolum
• Potentilla
• Polyanthus
• Lupin
• Impatiens
• Bellis
• Helleborus
• Althaea
• Convallaria
• Tiarella
• Pelargonium
• Malva
• Stokesia
• Astilbe
• Pulmonaria
• Astrantia
• Catananche
• Bergenia
• Campanula
• Delphinium
• Echinops
• Geranium
• Viola
• Aquilegia
• Monarda
• Hemerocallis
• Trollius

This is a large, diverse and useful group of plants. It would be easy to fill your garden with nothing but perennials and still have plants of all shapes, sizes and colours. This was the principle behind the nineteenth-century herbaceous border, which - though stunningly beautiful from late spring to late summer - had the disadvantage of descending into dullness from late autumn to spring. The modern mixed border makes the most of the qualities of perennials while compensating for their shortcomings with shrubs, bulbs, annuals and biennials. Unlike the herbaceous borders of old, which were traditionally rectangular but very large - often 3 m/ 10 ft deep and three times as long - the mixed border can be irregular in shape. Today curved lines are preferred to strict symmetry except in the most formal settings. Borders are smaller and, where space permits, island beds in the middle of lawns are popular. Again, curved lines are preferable; an indented oval is a pleasing shape and one which makes it easy to get close to plants that need attention, In any but the narrowest borders, it is a good idea to set stepping stones into the soil here and there to enable you to approach plants at the back for staking, dead-heading and other routine tasks like cutting down the stems after flowering and division when necessary. Bear in mind the space that most perennials need, and do not try to cramp them in too small an area. If your border is very narrow, dwarf shrubs, bulbs and a climber at the back might be a better combination.

The long life of most perennials is what makes them an attractive proposition to today's busy gardeners. Perennials are a more or less permanent fixture, with the exception of some short-lived species like delphiniums and hollyhocks (Althaea rosea), which need replacing after about five years. Because of this longevity perennials should be chosen and sited with almost as much care as you would bestow upon a shrub or tree. This applies particularly to species like peonies and Christmas roses (Helleborus niger), which greatly resent disturbance but, if left alone, will bloom through countless seasons. Other species, by contrast, need to be divided regularly not only for propagation purposes but to look their best. Astilbe, coreopsis and viola fall into this category.

CHOOSING PERENNIALS When designing a flowerbed where the principal elements are perennial, it is useful to make a plan on paper. This will enable you to site plants of different heights and colours in a pleasing relation to each other, bearing in mind flowering time, the ultimate spread of the plants and their particular requirements as to site and soil. Always set perennials the correct distance apart, and if the bare space between them when they are young and small displeases you, fill it up with annuals. Eventually the perennials will fill up the gaps. Indeed, many make excellent ground cover plants, giving a luxurious effectand smothering weeds. Some perennials which perform this function are bergenia, brunnera, Euphor'bla robbiae, Geranium endressii, pulmonaria and stokesia.

Because flower colour is the single most important factor affecting choice of plants, the entries in this book have been arranged in colour groups as far as possible. Other design considerations to be taken into account are height and quality of foliage. Tall plants which should be situated at the back of the border or towards the centres of an island bed are some campanulas, delphiniums, echinops, hollyhocks, lupins and mallow (Malva alcea). A border should be twice as wide as the tallest plant in it. The middle range includes Alchemilla mollis, astilbe, catananche, Monarda didyma, peonies, poppies and trollius. At the front of the border you might place low-grovving plants such as Bellis perennis, Oenethera missouriensis, dwarf coreopsis, geraniums, potentilla, polyanthus, Stokesia laevis and violas. Alchemilla, euphorbia, pulmonaria, bergenia and brunnera are among perennials prized for their foliage.

Hardy perennials can be purchased in containers or bare root direct from the nursery or garden centre. The planting procedure is identical whichever way they arrive. Dig a hole with a trowel or spade about one and a half times as large as the root ball. Set the plant in the hole so that its crown (the point at which the annual stems arise) is about 2.5cm/1in below the surrounding soil surface. Fill in around the roots and firm with fists or feet, depending on the size of the plant. To save on expensive garden centre bills, ask your friends and neighbours if you can take cuttings or make divisions from their perennials to establish in your own garden.
The choice of perennials is so wide that they can be used to contribute to any type of garden design - there is undoubtedly a perennial for every situation. It is this versatility that makes them the most valuable group of plants.