Why native wildflowers earn their place in pots

Native wildflowers do something bedding plants rarely manage: they feed the insects that feed your birds, and then they feed the birds directly. A pot of common knapweed, teasel or wild carrot left to set seed will draw in goldfinches, greenfinches and the occasional linnet through autumn and winter. In summer, the same plants hum with hoverflies, bees and beetles — the soft, protein-rich food that blue tits and robins need for growing chicks. You do not need a meadow to make a difference. A few generous pots on a patio, beside a back door or along a sunny wall will do the job beautifully, and they are far easier to manage than a patch of rough grass.

Compost, containers and the peat-free question

Peat-free compost is the only sensible choice, and it works perfectly well once you understand its quirks. Look for a mix based on bark, wood fibre, coir or composted green waste. It holds water differently from peat, and the surface can dry out surprisingly fast on a warm day, so check it daily. Choose a pot at least 15cm across with drainage holes at the bottom; a wide, shallow pan suits scattered seed better than a narrow deep one. Fill it to within a centimetre of the rim, tap it down gently, then stand the pot in a tray of water until the surface darkens. Starting with damp compost means you will not wash your seeds into a corner when you first water them.

Scatter thinly, cover lightly, and give perennials their cold

Thin sowing is the single thing gardeners most often get wrong. Crowded seedlings compete for light and nutrients, damp off, and never reach a size where they can be moved on. Aim for a few millimetres between seeds, which looks absurdly sparse at the time. If the seed is dust-fine — poppies, foxgloves and cornflowers all are — tip it into a jam jar with a pinch of dry silver sand or a little dry compost, shake to blend, and sprinkle that across the surface. It gives you far more control.

• Most UK wildflowers need light to germinate, so press the seed gently into the surface with the flat of your hand rather than burying it.
• At most, dust a couple of millimetres of compost or vermiculite over larger seeds such as field scabious or knapweed.
• Label the pot with the species and the date. You will forget, and seedlings all look alike at first.
• Annuals such as corn marigold and cornflower germinate in a fortnight at room temperature. Perennials — betony, wild carrot, oxeye daisy — usually need a cold spell first. Sow them in early autumn and leave the pot outside in a sheltered spot, or chill a spring-sown pot in the fridge for four to six weeks.

Watering, damping off and the waiting game

Keep the compost moist but never sodden, and water from below wherever you can: stand the pot in a tray, let it drink for twenty minutes, then tip the surplus away. If you must water from above, use a fine rose and do it in the morning so the surface dries a little during the day. Damping off — that tell-tale collapse of seedlings at soil level — thrives in still, wet, overcrowded conditions, so give the pots good airflow and remove any fallen seedlings promptly. Germination is uneven and unhurried: some species will appear in ten days, others in eight weeks. Keep the pot going for a full season before you decide it has failed.

Transplanting seedlings once they are big enough

Wait until each seedling has its first pair of true leaves — the ones that look like miniature versions of the adult plant, not the smooth oval seed leaves that appeared first. Then prick them out into individual 9cm pots of peat-free compost. Ease each one up with a pencil or a small dibber, lifting it by a leaf rather than the stem, which bruises easily. Make a hole, drop the roots in, firm gently and water in. Keep the new pots somewhere bright but cool and out of fierce midday sun, and give them a week or two to settle before you think about moving them again.

Growing on, planting out and leaving seed for the birds

Let the plants grow on until the roots fill their pots, then harden them off over a week or so by standing them outside during the day and bringing them in at night. Plant out after the last frost, usually late May or early June in most of the UK, though earlier in the south-west. Perennials establish best planted in September or early October, while the soil is still warm. Choose a sunny, sheltered spot and water well for the first few weeks.

Then comes the part that matters most for wildlife: do not deadhead. Leave the flowers to set seed and stand through the winter. Teasel heads, knapweed and wild carrot are all superb winter larder for finches, and the hollow stems shelter overwintering insects. Cut everything back in late February or March, just as new growth stirs, and leave the cuttings in a loose pile at the back of a border. Add a shallow dish of water nearby, refreshed every day or two, and your pots will have earned their place many times over.