Why early autumn is the best time to sow

Late August to mid-October is the sweet spot for sowing a wildflower meadow in Britain. The soil is still warm from summer, so seeds that are ready to go will germinate and root before the cold sets in, and those that need a period of cold to break their dormancy get exactly that from a British winter. Come March, your meadow is already up and running while spring-sown seed is only just thinking about it.

There is a practical advantage, too. Autumn rain does the watering for you, and the seedlings get a head start on the annual weeds that would otherwise swamp them in April and May. Aim to sow before the end of October on lighter soils, and by the middle of the month on heavy clay, where cold, wet ground slows everything down. If you miss the window entirely, don't panic — a spring sowing will work, but you will need to water it and you should expect a slower, patchier start.

Choose seed that suits your soil

Buy a mix of British native wildflowers and grasses, not a general-purpose "bee mix" of garden annuals. A traditional meadow mix is roughly 80 per cent grass and 20 per cent wildflower by weight, which gives something close to a 50:50 split in the number of plants. Match it to what you actually have underfoot.

• Heavy clay and damp ground: meadowsweet, ragged robin, greater burnet, devil's-bit scabious, tufted vetch, with crested dog's-tail and sweet vernal grass.
• Chalk and limestone: common knapweed, ox-eye daisy, salad burnet, small scabious, wild marjoram, quaking grass and sheep's fescue.
• Light, sandy or acidic soils: sheep's sorrel, harebell, tormentil, betony and common cat's-ear, with bent and fescue grasses.

If you want colour in the first summer, add a handful of cornfield annuals — poppies, cornflowers and corn marigold. They will flower within weeks, then fade away as the perennials take hold.

Clear the ground — and resist the compost

This is where most wildflower sowings fail. Wildflowers want a lean, open seedbed, so the two jobs are removing existing vegetation and reducing fertility. Do not dig in compost, manure or fertiliser; richness feeds grass and docks, not ox-eye daisies.

On a small patch, mow the growth as short as you can, then strip the turf with a spade, cutting about 2–3 cm deep. On larger areas, smother the ground with black polythene for a full growing season, or cultivate and harrow repeatedly over several weeks to exhaust the weed seeds near the surface. If your soil is really rich — an old vegetable plot, say — take off the top 5–10 cm of soil and move it elsewhere.

Once cleared, rake to a fine, crumbly tilth and firm the surface by treading or rolling. A seedbed that is firm and level gives good seed-to-soil contact and holds moisture far better than a loose, fluffy one.

Scatter thinly, evenly and shallowly

Wildflower seed is expensive and easily wasted by sowing too thickly. A grass-and-wildflower mix goes down at about 4–5 g per square metre; a pure wildflower mix at just 1–2 g per square metre. Weigh it out rather than guessing, then divide it into two equal piles.

To spread it evenly, mix each pile with ten times its volume of dry silver sand or fine vermiculite. That bulks it out so you can see where you have been, and it stops the seed clumping together. Broadcast the first half walking in one direction, then the second half walking at right angles across it. Finish by raking very lightly or simply treading the seed in — no more than 5 mm deep, as many wildflowers need light to germinate. There is no need to water unless the weather turns unseasonably dry for a fortnight or more.

Yellow rattle: the meadow-maker's secret

If there is one plant worth going out of your way for, it is yellow rattle. It is semi-parasitic on grass roots, weakening the grasses just enough to let wildflowers through. Without it, a vigorous sward will simply close over your flowers within two or three years.

Sow yellow rattle in autumn at roughly 0.5–1 g per square metre, scattered over the surface and firmed in. It needs the cold of winter to germinate, and it needs grass roots nearby to latch onto, so avoid sowing it into bare, grass-free ground. It is slow to establish, often showing only as scattered plants in the first year, but once it settles it spreads itself and does the hard work for you.

Through winter and the first summer

Other than keeping an eye out for slugs on young seedlings, leave the meadow alone until spring. Don't tidy, don't feed, and don't worry if the surface looks bare — much of the growth is happening below ground.

In the first summer, mow the meadow every six to eight weeks down to about 5–7 cm, always removing the cuttings. This feels brutal, but it encourages strong roots, keeps annual weeds in check and lets light reach the seedlings. If you sowed cornfield annuals, let them flower first — roughly six to eight weeks — then cut.

From the second year, switch to a traditional hay regime: one main cut in late July or early August once the flowers have set seed, leave the hay lying for a few days to shed seed, then remove it, followed by a second cut in autumn if growth is strong. Remove the cuttings every time. A meadow fed by its own rotting hay quickly turns back into rough grass, and all your autumn work is undone.

Be patient. A sown meadow takes three or four years to look like the ones in the photographs, and it will never look the same two summers running. That is entirely the point.