Save zinnia seeds for next season.

1. Choose which flowers to leave

Mark a few healthy plants while you can still see the flowers you like. Stop deadheading those selected blooms and let them develop seedheads. You can continue removing faded flowers elsewhere if you want the remaining plants to keep flowering.

Read the seed packet before expecting identical offspring. Seed from a hybrid can produce different colors, sizes or flower forms. Saving a favorite pink bloom does not guarantee another pink bloom. Keep the original cultivar name as the parent record, rather than presenting the saved seed as guaranteed true to that variety.

2. Wait for a mature, dry head

A faded petal alone is not the harvest signal. Look for a flower head that has become brown, shrivelled and dry, including the base. Collect mature heads with clean snips and put each batch in a labelled paper bag. If a flower is still soft and green underneath, leave it to mature.

Keep batches separate during further drying in an airy indoor place. Do not seal damp flower heads in plastic. Timing follows the plant and weather rather than a universal autumn date. The zinnia growing guide covers the flowering plant before this stage.

3. Keep both kinds of seed

Gently break apart a dry head over a tray. Zinnias can form seeds in both the outer ray flowers and the central disk flowers. New Mexico State University explains that the shapes differ and both can be fertile; sorting out every seed by shape is unnecessary.

Remove loose, bulky petals and stems if convenient, but keeping dry seedhead material is an option when identifying every small seed is frustrating. Some structures may be empty. Neither a dark color nor one particular shape proves that every seed will germinate. Label the batch before moving on to a different plant.

4. Make a simple storage record

Once completely dry, keep the seed in a paper envelope in a cool, dry place away from direct light. Avoid a hot greenhouse or a damp garden shed. Check for moisture or mold before putting the batch away; drying is more useful than choosing an elaborate container.

• Plant: zinnia, plus the parent variety if known.
• Collected: actual date and garden location.
• Expectation: parent flower color; offspring may vary.
• Next step: sow in the locally suitable warm growing season.

Keep a modest amount and use the rest only if it stays sound. For separate autumn planting ideas, see flowers to plant in fall; saving seed now is not an instruction to sow tender zinnias into cold soil.