The small size, 5.7 cm by 8.8 cm, meant for fine seed. Lettuces, carrots, radishes, basil, oregano, thyme, chamomile, poppies, amaranth: these are seeds where a pinch sows a full row, and which get lost in a large half-empty envelope. This size also files far better — a shoe box easily holds a hundred of them, upright and sorted.

Almost everything we sell is open-pollinated, which means you can save your own seed and sow it again indefinitely. These envelopes are the tool for that.

What to write on it: the exact variety name and the harvest year, at minimum. On a small format there's little room left, so go to the essential and keep the longer notes in a notebook, with the same number copied onto the envelope. Three winters later, that label is the difference between a precious lot and an anonymous one you end up throwing out.

Why paper and not plastic: paper breathes. A seed still slightly damp when bagged goes on drying through the envelope; in airtight plastic, the same moisture stays trapped and moulds the lot. It's the leading cause of failure in seed saving.

For storage: keep the filled envelopes in a closed glass jar with a silica gel packet, cool and dark. Most fine seeds hold a good germination rate for two to four years, a little less than large seeds like beans.

• Measures 5.7 cm × 8.8 cm (2.25" × 3.5").
• Made of recyclable paper, which lets the seeds breathe.
• Available in packs of 20, 100 or 500.
• Suits fine seeds: lettuces, carrots, radishes, herbs, flowers.
• Write variety and harvest year. Store cool, dry and dark.