self-seeding plants: creating a fuss-free garden

The more I look at natural landscapes and the wild flowers that scatter themselves within them, the less inclined I am to garden meticulously.

I want my outside space to produce food and flowers, and I want to plant trees, but purely ornamental gardening feels increasingly pointless to me, especially with our unpredictable English weather. Our mixed borders, which used to be designed and tweaked on a regular basis, have been largely given over to the dominance of self-sowers.

As long as you have a strong structure of walls and paths, shrubs and climbers, the planting that goes on in their skirts can be, at least in part, self-perpetuating. And with the eight plants below, I’m happy for them to do their own gardening.

You can’t take this laissez-faire attitude in a new or neglected garden, as the self-sown weeds choke the rest. Annuals such as groundsel, bittercress, bird’s-eye speedwell and sour thistle appear among the interesting, planted things, and the place becomes hard to keep on top of. But if your soil is relatively clean of weed seed after several years of regular tidy-ups, then what germinates in spring is usually desirable.

You’ll have to move away from mulching your beds deeply with compost or green waste, as mulches will smother nascent seedlings – good and bad – another reason why your soil needs to be quite clean before you start with this non-intervention style of gardening.

In my oast garden, now 15 years old, self-sowers knit together and fill any spare chink of space, with little human attention or meddling. Ten years after we planted 50 bulbs, the stalwart allium 'Purple Sensation’ has come to dominate, so I’ll dig out some this year once flowering is over. However, on the whole, a handful of excellent plants keep each other in balance.

Seedlings tend to collect in the light, open space at the front of the borders, so we dig them up in good clumps and transplant them farther back to spread them out more evenly. This works with all but the tap-rooted plants, such as eryngiums and, to a lesser extent, honesty, which either need to be dug up when small or root-balled with plenty of soil.

In the early part of the year, the purple honesty creates prominent ribbons right through the garden. I put in lots of tulips, in tall pots as well as in the ground, but this would be boring without the honesty, which stands out against a backdrop of acid-green feather dusters of Euphorbia characias subsp. wulfenii 'John Tomlinson’ (AGM). I brought three plants from my parents’ garden nearly 20 years ago and let them scatter themselves liberally almost wherever they chose. There are now 20-30 plants on the south-facing bank below the school and another five or six whoppers in the shelter of the oast garden.

These overlap in their dominant, acid-green moment with the miraculous triennial Smyrnium perfoliatum. I love this airy-flowered Mediterranean native. In its first spring, months after germination, it produces a tiny seedling, with perhaps only three pairs of leaves. At this stage, it has a small tuber, about the size of the top of my little finger.

The leaves die down by midsummer, but the tuber continues to grow.

By year two the plants are bigger, with perhaps seven or eight leaves, but are still not large. It’s often at this stage that they’re weeded out, confused with ground elder, but the tubers are now the size of a small new potato. The foliage again dies back, but in the third year they come up to flower and will look magnificent in sun or shade for eight to 10 weeks before fading. Even then, the delicacy and longevity of its skeleton make this one of the classiest dried stems to bring inside for the winter. It will have self-sown, so you’ll have a gap of one year, but then you’re on a smyrnium roll. Now, in June, is the moment to find a friend to let you dig up a small clump, which should contain one and two-year-old seedlings. They can then begin their life cycle in your garden.

A simple purple aquilegia pops up all through the garden, too, and sometimes a double that has crossbred with 'Ruby Port’ or 'Blue Barlow’, a good accidental understorey to the allium. Then, as these go over, Eryngium giganteum throws up its egg flowers with their silvery barbed-wire halo. This sea holly is the epitome of a self-sower, only germinating freely from fresh seed. Even gathered straight from the plant in late summer and sown into a seed tray under cover, it never germinates as well as when it does the whole process itself, tucking itself between other plants to pop up the following year – almost always in excellent combinations.

The same is true of Angelica archangelica, which grows well in sun or dappled shade. I encourage as much of this plant as I have room for, as it’s an excellent long-lasting flower and seedpod for arranging, but it is a giant, with plants reaching 6ft in one season. For a gargantuan combination, encourage the silver, felted-leaved, giant thistle Onopordum acanthium to spread itself, too; it grows from a self-sown seedling a few inches high to a 7-8ft plant by midsummer.

The final threads of self-sown colour come from dill and a series of opium poppies, whose silver seedpods are almost as good as the flowers, and last in good heart until Verbena bonariensis takes centre stage. This only self-sows on soil with good drainage, but even on my heavy clay, with plenty of grit added, it creates invaluable purple rivers from east to west, north to south, until the start of winter.

And those to avoid...

I regret introducing root colonisers, such as plume poppy (Macleaya cordata), the crimson-leaved Lysimachia ciliata ‘Firecracker’ and the silver grass Elymus magellanicus. Every two or three years, they have to be dug out in swaths. Left to their own devices, they’ll swamp other less-robust things and quickly reduce your plant range by their brutish domination. Most self-sowers are more modest in the way they occupy their space. However, I’m a little wary of Atriplex hortensis var. rubra (orache), fennel, borage and forget-me-nots. All are a bit too prolific in their seed production and take over whole corners.

This article first appeared in the Daily Telegraph on 21st June 2013.