Gardens: Plants that reproduce all by themselves are loved by some gardeners, hated by others
When I take a look at my high-summer garden, I have to admit that I am quite pleased with certain rather dramatic plant scenes about the place. A conclave of giant echiums gathers importantly near the end of the plot, their four-metre towers of flower humming with bees; fountains of rust-and-green pheasant's-tail grass surge out from under the bamboos. In a forlorn corner, white foxgloves and deep-red opium poppies brighten the mood with their pale spires and ruby splashes; spiky teasels guard the edges of the path; and here and there woolly verbascums shoot up from the ground, their knobbly stems dotted with floppy yellow flowers.
I glow gently, taking it all in, and think "what a great gardener I am". Then I have another look, and realise that every single one of these perfectly-placed plants has had very little to do with me. They have all self-seeded from somewhere else.
It's true that I brought their forebears into the garden many generations ago, and carefully planted them in some bed or other, but this current arrangement, some years later, is entirely of their own making. Those Canary Island echiums, for instance, started out about eight years ago, as a solitary specimen, some 30m nearer to the house. Its children and grandchildren gradually migrated down the garden, until they made a homeland in an awkward area between the compost heap and the vegetable patch.
The New Zealand pheasant's tail grass originated as seven precisely-positioned clumps. But their progeny - not content with such strict accommodation - colonised the dry and bare ground under the bamboos, where nothing else would grow, except for dandelions. (This grass has been subject to a number of name changes: so if you're still calling it Stipa arundinacea, it's time to start thinking of it as Anemanthele lessoniana - 10 syllables to remember, rather than eight.)
The foxgloves, teasels and verbascums are all part of the same story of floral trekking and settling. So are the opium poppies, but I've practised some iron-fisted eugenics on them over the years, whipping out all the plants with blooms of an orangey red, cheap lipstick colour, and letting only those breed that have more classy wine-and-cerise petals.
I love this kind of gardening, where plants wander like nomads from bed to bed, and from border to gravel path (the best germinating medium for many kinds of volunteer seedlings). Their seeds lodge in nooks and crannies, where planting trowels would never venture, and grow into unexpected surprises.
Such unplanned arrivals create a pleasingly naturalistic atmosphere, and can make the difference between a tight-lipped, buttoned-up garden and a friendly and relaxed space.
Yet, maintaining a garden that looks so free and easy requires some care. Weeding is best done on hands and knees, rather than with a hoe, so that one can get to know the infant forms of desirable plants, and preserve them if they usefully fill a gap.
A ruthless streak is also required: if you were to allow every freelance seedling to set up shop wherever it liked, you'd soon have nothing in your patch except for a handful of self-seeding species. It's worth remembering that the reason certain plants pop up all over the place is that they are toughies and invaders, ready to take over any bare bits of earth, and to crowd out the less resilient inhabitants.
For every echium, teasel and clump of pheasant's tail grass that reaches maturity in my garden, I raze hundreds; for every opium poppy and foxglove, I cull dozens; and each verbascum loses a handful of siblings within a month or two of their felty grey leaves appearing above ground.
Some eager-to-seed species can quickly turn into overly persistent guests: red valerian (Centranthus ruber), for example. The pink-, red- or white-bloomed Mediterranean native was introduced in the 19th century as a garden plant, but it soon started making itself at home in dry and stony habitats: along railway lines and on walls. Nowadays, few of us grow it intentionally, but it usually gate-crashes dry, town gardens, where it drills its long taproots into walls and crevices. It is strikingly pretty, with its candy-coloured blooms, but if your walls are old and crumbling, the roots can jimmy the mortar and stones apart.
There are self-seeders that are treasured by some gardeners, but abhorred by others. Lady's mantle (Alchemilla mollis) is welcome in my little domain, especially when its scalloped leaves are spangled with a diamondy shimmer of dew and rain. And what's more, its frothy, lime-green flowers make the most ham-fisted flower arrangement look instantly better. My garden is small enough that I don't mind weeding out its abundant progeny, but in damper, larger gardens it may become a pest.
One way to stop profligate seeding is, obviously, to remove the spent flower heads before the seeds ripen. The tidy gardener rarely has a problem with plagues of unwanted seedlings. On the other hand, he may be losing out on nature's bounty of free plants - often placed far better than any plantsperson could ever manage.