The hit of a pot in full flower, the rush of a purchase that gives you instant colour – these are the garden’s way of luring you in. Biennials play a longer game; you need sow now to receive your prize next year. But oh boy, is it worth it, as these low-growing rosettes of unassuming leaves rise to their glory: foxgloves, angelicas, eryngiums, echiums, sweet rocket, honesty, many campanulas, wild carrots, forget-me-nots, teasels, milk thistles, wallflowers or the dusky purple-pink flowers of Delphinium requienii.
Behind all of these is an extensive root system, often a tap root that drills down to the good stuff, gathering up supplies for the second-year explosion. The towering flower spike that comes with these plants often appears in early summer; think of the spectacular spires of a mullein or foxglove and their thousands of fine seeds. This is an evolutionary strategy to maximise seed production: if you flower in early summer, there is often adequate moisture in the soil and less competition from larger plants for sun.
The joy for the gardener is that these flowers appear when your eye needs lifting away from things that are now fading, such as spent tulips and forget-me-knots. Sprinkle a few biennials across your scheme and you’ll find, even before they open, your eye is drawn their way – the flower stem of an eryngium or angelica unopened is as interesting as the final flourish. They tend to be good pollinator plants, too.
Once established, you don’t have to sow afterwards. They are usually prolific self-seeders, and will move themselves around your space as they see fit.
Sow under cover now – they will need a little heat, 18-20C – or outside by the end of the month. You can sow through till July, either direct or into seed trays outside; if in trays they will need potting up to be planted out in autumn or the following spring. The first to be sown are campanulas, angelicas, foxgloves and aquilegias.
Or buy plants. If you buy plugs, such as clary sage, from naturescape.co.uk (wonderful branching bracts of handsome white flowers), they may not flower till next year, but they will flower earlier than those from seed. Or buy larger, more expensive plants, from £6-£12, that will flower this year, such as the foxglove Digitalis purpurea ‘Sutton’s Apricot’, with its soft apricot-pink flowers and mottled brown throat (from sarahraven.com). But those who sprinkle seeds will have many more plants to play with for a fraction of the price.