Reading the season: when native seed is ripe

There is a fortnight or so each autumn when the whole wet meadow seems to let go at once. Between late August and mid-October, depending on where you are and how the year has run, our native grasses and sedges set seed and shed it on the first windy day. Get the timing right and you can gather enough to grow a modest meadow or a damp hollow in the garden. Get it wrong and you carry home a packet of empty husks. The trick is to visit the same patch every few days and watch the colour of the seed heads rather than the calendar.

Judging ripeness in grasses and sedges

Grasses and sedges ripen differently, and they are worth learning apart. Most grasses are ready when the head has turned from green or purple to straw, buff or brown, and the seed comes away as you run your fingers upwards along the stem. Cup a head in your palm and tap it gently; a shower of small, dry, brown seed means you have timed it well. Anything milky, green or squashy is not ready, and seed collected too early will not ripen in a paper packet, however carefully you store it. Grasses shed quickly, often within a week, so plan two or three short visits rather than one long raid.

Sedges behave differently. Their seed sits inside small, bottle-shaped utricles, and you are waiting for those to darken to brown or black and for the whole head to feel dry and slightly stiff. Common sedge, brown sedge and greater pond sedge can all be checked by bending a single spikelet; ripe seed slips out with a light rub, while unripe seed clings on. Purple moor-grass and tufted hair-grass shed heavily, so take your bags to them on the first still, dry morning you can manage.

Collecting well on a dry day

• Go out on a dry day, ideally late morning once any dew has lifted. Wet seed heads mould in storage.
• Take paper bags or envelopes, sharp scissors or secateurs, a pencil and a small notebook.
• Cut stems 20–30 cm below the seed head, hold the head inside the bag and tap or bend it so the seed falls in. Never pull a plant up by the roots.
• Take only a small share — roughly one head in ten — and never strip a single clump.
• Ask before collecting on a nature reserve, a site of special scientific interest or private land. On a wetland site, tell someone where you are going and keep clear of soft ground and deep pools.

Paper packets and labels that still make sense in March

Seed keeps best in paper that breathes. Fold your own packets from newspaper, or use small paper envelopes, and never use plastic bags, which trap damp and encourage mould within days. Label every packet as you fill it, not later in the car. Write with pencil or a permanent marker, and put a second label inside the packet as well as one on the outside, because outer labels do go astray.

A good label carries four things: the species, the place, the date and the habitat. Something like Deschampsia cespitosa, tufted hair-grass — mill meadow, damp clay, 14 September will tell you more in February than a name alone. Add a grid reference if you use one, and a short note on the weather. If you cannot identify a plant with confidence, give it a working name and note what grew beside it; the label is there to jog your memory, not to prove anything to anybody.

Drying and storing in a cool, airy place

Spread the seed thinly on newspaper or in shallow trays in a dry, airy room out of direct sun, and leave it for a fortnight. Turn it gently every day or two so nothing sits damp at the bottom. It is dry when a seed snaps between your fingers rather than bending, and the heads rustle when you move them. Then close the packets in a tin or a sturdy box, label the box, and keep it in a cool, airy place — a shed, a garage or an unheated room — away from mice and damp. Check once a month and discard anything showing webbing or grey mould.

Sow within a year or two where you can. Many of our wetland sedges lose viability quickly, and seed sown in late autumn or early winter, when the ground is wet and cold, tends to behave much as it would in the wild.

Notes from the wetland edge

Seed collecting is halfway to nature writing, because both begin with standing still and paying attention. Keep a notebook with your packets and record what the day was doing: the level of water in the dyke, the pale rattle of seed heads in the wind, snipe lifting off a rushy corner, the smell of wet peat and the first frosts. A note made on the spot, with muddy fingers, is worth a page written from memory at the kitchen table.

Over a few seasons those notes become more than a record. They show you which plants set good seed in wet years and which in dry ones, how early the sedges shed, and how a meadow changes when the grazing stops. Sow sparingly, label everything, and let the patch you collected from go on seeding itself.