Which plants can you depend on for the following? Non-stop colour from spring to autumn; hardy and easy to grow; need sowing just once; help boost populations of beneficial, pest-checking insects.
A cryptic clue: these are the same plants that will gently populate your garden, whatever its size, making the most of niches where other plants and crops fear or fail to grow.
The answer, of course, is a mix of “self-seeding” plants. When I began terracing the bracken-riddled bank that I am slowly transforming into my garden, the soil was crying out for new life. Lashings of compost and leaf mould have gone in. But I’ve also added the magic ingredient which, if the clouds of bees and hoverflies are anything to judge by, is working wonders.
Self-seeders are plants – usually annuals or biennials – that scatter copious amounts of seed into the soil. These germinate, often within weeks of being shed, and grow steadily, without fuss, eventually flowering, seeding, then doing it all over again, more or less forever. Because they sow themselves, they pop up in places we’d never dream of planting. They appear along the edges of borders and beds, in vegetable and fruit plots, in gravel paths and drives, and in nooks and crannies in paving and walls. Most self-seeders are blessed with blooms that beneficial insects find irresistible, tempting pollinators, predators and parasitoids to flood your garden.
Now’s a good time to set the self-seeding ball rolling. Hardy self-seeders sown now will make young plants before winter, and flower from next spring. You can buy seeds to start with (you’ll probably only ever need one packet of each), or cadge ripening seeds from friends.
Sowing is easy: amble around your plot, and sprinkle a few seeds here and there as you go.
1 Checks and balances
Your gardening instincts should intervene when needed. If a self-sown borage is swamping its neighbours, out it comes. As you get to know your self-seeders, you’ll develop a feel for which plants can be left to do their own thing. If you’ve masses of self-sown seedlings in one part of the garden, turn them into movable feasts. Transplant seedlings when young, keeping a clump of moist soil around their roots, any time from autumn to spring.
2 Biennial bearings
Foxgloves and honesty, both prolific self-seeders, are biennial. They germinate and produce plants during the summer and autumn, then sit tight over winter. In spring they start growing again, then flower. Biennial self-seeders can aid planning: note plants growing now, as they will flower in the same spot next spring.
3 Know your seedlings
It pays to get to know your self-seeders as juveniles. Being able to tell them apart from weeds means you can hoe off the latter, leaving any self-seeders intact. Some are easier to spot than others: the ribbed, bristly leaves of borage; slightly tacky, glistening pot marigold leaves; and the ferny, blue-green foliage of California poppy soon become familiar. One certain way of identifying self-seeders is to sow a pinch of each in a labelled row, and watch them grow.
4 Pop-up salads
Many edible crops will sow themselves. Since adding a handful of oriental vegetable seeds to my compost, I’ve had red mustard and mizuna popping up all over, year after year. These impromptu greens taste just as good as planned sowings (and seem to lead a charmed life when slugs abound). Leave some to flower and produce seed. If you fancy picking self-sown lettuce, allow a plant to bolt, flower and scatter its seeds. For peppery greens all winter, land cress (Barbarea verna) will sow its own way, but do pull up any surplus plants when young.
5 Hot spots
Most seedlings find it tough in sun-baked gravel, stone or the slate chips used on paths and drives. But not the California poppy, which thrives in dry spots with scant soil. Scattering a packet of seeds (insects favour single varieties) brings new life to an otherwise overlooked space. Any unwanted seedlings are easy to spot, and easier to tug up.
6 Cash in on crevices
My garden is terraced with slate retaining walls built the traditional, no-mortar way. After scattering thousands of Welsh poppy seeds over several years, only a feeble few plants appeared – until I started sowing sideways into the walls’ crevices. Now I have clumps of these perennial poppies, in yellow and orange, in the wall skirting one end of my greenhouse. In spring they’re among the first flowers used as feeding stations by wild bees and hoverflies emerging from their winter slumber. To sow sideways into a wall, mix seeds with soil and push it into the cracks, or push the dry pepper-pot seedheads into gaps between the stones.
7 Compost mixer
An easy way to distribute self-seeders is to add them to a “cool”, slow-rotting compost heap or bin (they’ll just perish in “hot” compost). Compost seedheads just before they ripen and drop their cargo. Seeds mixed in t he mature compost will lie dormant until you use it to improve or to mulch your soil, germinating when they see the light.
8 Think single
To boost the biodiversity of your plot, choose simple and single flowers, rather than intricate doubles. Single blooms allow bees, butterflies and other insects access to pollen and nectar, which are often, along with scent, absent from multi-petalled blooms.
John's must-have self seed plants
Alyssum (Lobularia maritima)
Borage (Borago officinalis)
Buckwheat (Fagopyrum esculentum)
California poppy (Eschscholzia californica)
Cornflower (Centaurea cyanus)
Common foxglove (Digitalis purpurea)
Honesty (Lunaria annua)
Nasturtium (Tropaeolum majus)
Opium poppy (Papaver somniferum)
Poached egg flower (Limnanthes douglasii)
Pot marigold (Calendula officinalis)
Sunflower (Helianthus annuus)
Teasel (Dipsacus fullonum)
Welsh poppy (Meconopsis cambrica)