Check what you are actually sharing
Separate packets by crop species, cultivar name and harvest year. For home-saved seed, record where the parent plant grew and whether it may have been cross-pollinated. Open-pollinated varieties can be useful for seed saving, but they are not automatically true-to-type if compatible cultivars flowered nearby. Seed collected from a modern F1 hybrid often produces varied offspring. If identification is uncertain, be open about that rather than offering an apparently guaranteed cultivar.
Prepare clean and useful packets
Seeds should be dry, healthy-looking and free from obvious insects or mould before you put them into small breathable or suitable airtight packets for storage, depending on seed condition. Label each packet with the crop, cultivar if known, harvest date and approximate quantity. If a batch is old or its germination is unknown, test a small sample on damp paper and explain the result as a limited observation, not a promise. Keep the packets cool and dry until the exchange.
Make the meeting easy to use
Bring a simple list, spare labels, pens and separate trays for each crop. Exchange notes about sowing depth, climate, likely plant size and whether a support is needed. Do not distribute unidentified wild plants, damaged seed or anything showing signs of disease. When moving seed across borders or trading protected varieties, check the relevant plant-health and variety-right rules first. A small number of well-documented packets is more valuable than many mystery seeds.
After the swap
Keep acquired packets separate until you have checked their labels. Plan small trial sowings before relying on an unfamiliar variety for an entire bed. Record the sowing date, germination and later plant characteristics in your own garden notes. Good records help the next exchange and allow you to spot a batch that may not suit your local conditions.
Continue with the seasonal calendar or browse the plant directory before adapting the steps to local conditions.