Garden: Give me the flax

One of the great treats for anyone who visits the countryside in June is the sight of fields of the common flax, Linum usitatissimum, in flower. After the acid-yellow, in-your-face coarseness of the rape flowers in late spring, the cool blue of the flax is a welcoming sight. Its slender, delicate stems are set in motion by the gentlest breeze. It is an annual, with narrow, blue-green leaves on 45cm-tall stems apparently only just able to carry the flowers, which are open funnels of sky-blue. (After rain, the heads hang disconsolately, but soon perk up in the sunshine.)

The botanical name, Linum, gives a clue to this crop's use; it is for making linseed products or linen. It seems to be more widely grown these days, and I am thrilled about that; not only because the colour is so beautiful but because, unlike rape, this plant does not attract every pest under the sun - pests that, after rape is sprayed or harvested, have a habit of moving on to gardens. It is not easy to find seed of Linum usitatissimum to buy for sowing in the garden, but there are a number of related plants, both annual and perennial, which have both the delicate form of the common flax and the beautiful shape of its flowers - and come in a range of colours.

The most commonly grown annual is called Linum grandiflorum "Rubrum", which has satiny, deep-crimson-red flowers, with darker centres, on top of 30cm stems. There is a pure-white form, and one called "Bright Eyes", which is white with a chocolate centre.

It is the perennials that give the best value, however. One of the most attractive is a native, Linum perenne, which still grows in chalky grassland in certain areas of this country. It grows to about 30cm tall, has pale blue flowers for several months in the summer and thin, 5cm-long, blue- green leaves. There is a white form, "White Diamond", and a deeper blue called "Blau Saphir" or "Blue Sapphire", both of which come true from seed.

Bearing larger flowers, the colour of the Mediterranean on a sunny day - appropriately enough for a plant from southern Europe - is Linum narbonense. There is a fine form of it called "Heavenly Blue"'. This species may be preferable to the shorter lived Linum perenne, but it should not be considered bone-hardy, and needs a sheltered place in full sun and well- drained soil.

The perennial Linum flavum has a woody base up to 60cm tall, and showy, golden-yellow flowers. There is also a dwarf form called "Compactum", which grows no more than 20cm tall and has bright yellow blooms. You may find "Gemmell's Variety" listed in catalogues; I confess I have never seen it, but it sounds remarkably similar to "Compactum". Nevertheless, this variety has an Award of Garden Merit from the RHS, which is a recommendation to take seriously.

Perhaps the most charming of all is a little Mediterranean sub-shrub called Linum arboreum - "arboreum" means tree-like, but that is poetic licence for it only manages to grow to a height of 30cm. It has clear- yellow flowers, much like Linum flavum, and sticky stems.

In the British climate, at least, all types of ornamental flax grow best in full sun and well-drained soil. Most of the perennials are not long- lived in the garden, so it is best to take precautions and start off another crop by rooting stem-tip cuttings of the perennials now, or semi-ripe cuttings of shrubs late in the summer.

The annual Linum grandiflorum should be sown where it is to flower in a border, or pot, in the spring. Flaxes take a very dim view of being transplanted, so sow them thinly. In my experience, they germinate readily. They also flower for longer, if regularly deadheaded.

With the exception of Linum arboreum, which can be grown as a specimen individual, perhaps in a rock garden, these plants look nothing if you are miserly with them and sow or plant only a few together. Their personality is created by massing them, since individual plants are too delicate to make an impact except at very close quarters.

The trick with these plants is surely to grow them thickly and generously, so that you can create something of a summer shimmer in your own garden.