I have a friend – let’s call her “Mrs X” – who has developed an unfortunate habit. Through years of investing her time and energy in her garden Mrs X has become a knowledgeable plantswoman and great enthusiast, a voracious reader of horticultural literature and frequent visitor to gardens great and small. The trouble is, her own plot is relatively modest in size, and long ago Mrs X’s ambitions outgrew its boundaries.
Denied the acreage needed for further horticultural expression, Mrs X has instead taken the seasonal process of “editing” to extreme levels. Perennials are lifted and moved – they rarely get big or established enough to need dividing – every year, sometimes twice a year. Shrubs are not immune to her restless eye either, provided they haven’t attained a size that makes them impossible to shift. The object of this exercise isn’t simply to resolve any shortcomings in planting combinations. It is more a constant reinvention of the garden, to the point where it is almost unrecognisable from one year to the next, which for Mrs X is entirely the point.
Regular reinvention on such an unequivocal scale may be unusual – and potentially hazardous to one’s sanity – but a desire to keep gardens fresh, dynamic and changing is not uncommon, regardless of plot size. This is where annuals and specifically “direct sown” annuals have an invaluable role to play.
The term refers to hardy annual plants that can be grown from seed sown directly into a prepared seedbed outdoors, where they are free to grow and flower, rather than sown into trays or pots in a glasshouse and then slowly hardened off ready for transplanting. The benefits are easy to measure: no specialist kit is required, no glasshouse or cold frames, no pots, trays or potting compost. After sowing there is no need for the close monitoring associated with a glasshouse environment, and limited aftercare is required apart from a little thinning out of seedlings. Watering is usually only needed at the vulnerable germination and seedling stage, and then only if the weather turns very dry. Because these are hardy annuals the risk of weather damage from late frosts is reduced too, so there is less of the anxious weather-watching associated with the planting out of pot-grown annuals.
There are also aesthetic advantages to direct sowing: scattering seed around through established plants often results in happy accidents. Just as in the wild, seeds seem to find a way of germinating in the least auspicious places, with plants emerging from patches where it would be impossible to plant a pot-grown plant.
There are two main seasons for sowing. Traditionally, late spring has been touted as the optimum time to sow, just as the soil is beginning to warm and day length is increasing. In the wild, however, the annuals from which almost all our garden varieties are derived will have set and shed their seed in late summer or early autumn. Sowing across both seasons seems to be the optimum for some annuals: an autumn sowing takes advantage of the warm soil to encourage germination by late autumn. The resulting seedlings are surprisingly robust and will make it through even cold and snowy winters, resulting in a mid-spring show of flowers – by when it is time to sow again for a midsummer display. Sowing through spring and early summer in succession keeps things bubbling along nicely until late summer. Before sowing, the soil should be dug over and raked to a fine tilth, but if this is impossible – such as when sowing between established plants – make a seed bed by applying a layer of loam and sand to the surface of the soil.
The umbellifers make a useful contribution to the hardy annual tribe. There are several to recommend for their airy flower heads. Ammi majus, from the Nile river valley, is a classy cow parsley, about 120cm tall topped with white, lacy flowers. It prefers full sun or partial light shade. The variety “Graceland” is a good one, with larger heads and strong stems that make it good for cutting. Technically a biennial or shortlived perennial, the “true” cow parsley, Anthriscus sylvestris, has a handsome purple foliage form, “Ravenswing”. It gets a mention here because once established it will seed around and form a colony that will ensure a succession of flowering plants, suitable for a wild garden or meadow. Perhaps the most beautiful of the umbellifers is Orlaya grandiflora, the Minoan lace flower. At 60cm it prefers full sun and well-drained soil, and given those conditions will flower freely, producing flat clusters of long-lasting flowers that look like miniature lace-cap hydrangeas, that cut and keep well in a vase. In colder climates this is probably best left to a late spring sowing. Any of these white flowered umbellifers would make a classy counterpoint to silver-leaved foliage plants, dark-flowered salvia or metallic purple alliums.
Garden favourites such as Love-in-a-mist (Nigella damascena), Pot marigold (Calendula officinalis) and Plains coreopsis (Coreopsis tinctoria) are reliable colonisers too. Once sown they will usually reappear year after year, although it is important not to rely on their self-sowing capacities alone. Without regular topping up through a succession of sowings over a number of weeks the self-colonisers will flower and go over all too soon. Nigella is a plant that is as attractive in seed as in flower, and a succession of pale blue flowers alongside the papery, bladder-like seed heads should be the aim. Perhaps the best of all the colonisers is Eschscholzia californica, the Californian poppy. Behaving either as a perennial or annual, it will spread its filigree glaucous foliage and sunny orange flowers wherever there is sharply drained, gritty soil and plenty of sunshine. Once established, the need to resow diminishes, and the trick to keeping it flowering over a long period rests instead in dead heading, cutting back the spent flowers before they get a chance to form the distinctive, narrow seed pods. But let at least 25 per cent of the flowers go to seed if you want the colony to continue to thrive and regenerate. A broad sweep of Eschscholzia looks wonderful alongside the squirrel tail grass, Hordeum jubatum – another direct sown annual. Even the “common” cornfield weeds are worthy of consideration. The cornflower, Centaurea cyanus, has been heavily hybridised in recent years resulting in interesting colour breaks, dark purples and pinks, and a longer flowering season. This, along with varieties of Coreopsis and Tagetes, featured heavily in the annual meadows at the London 2012 Olympic Park.
Above all, direct sown annuals bring with them a somewhat haphazard aesthetic, a floral joie de vivre. In part, this must be because it is impossible to sow them in straight lines, unless one is spectacularly anal about such things, and so instead they pop up all over the place. And as so many are genuinely wild plants – or if not, first cousins of wild plants – there is something about them that touches a part of the soul other plants may not reach. They add vibrancy and movement to established planting schemes, fill empty nooks and crannies and refresh tired plantings with an injection of colour. I must post Mrs X a few packets.
Matthew Wilson is managing director of Clifton Nurseries, London
Robin Lane Fox is away