Zinnia

Zinnia elegans is a frost-tender annual native to Mexico, prized for its vivid, long-lasting blooms in nearly every colour of the spectrum. Plants range from compact 15 cm dwarfs perfect for containers to statuesque 90 cm border giants with flowers suited to cutting. It thrives in full sun and warm, well-drained soil, producing blooms continuously from midsummer until the first frost kills the plant. A superb pollinator magnet, it is one of the most rewarding annuals a gardener can grow.

Growing

Start seeds indoors 4–6 weeks before transplanting out, sowing 1.5 cm deep in modules or trays once indoor temperatures stay above 18 °C. Germination takes 7–10 days. Pot on once the first true leaves appear. Transplant outdoors only after all frost risk has passed and nights remain above 10 °C, spacing plants 20 cm apart in a sunny, sheltered position. For direct sowing, wait until soil reaches 18 °C and sow at the same depth, thinning to 20 cm.

Care

Water at the base rather than overhead to prevent powdery mildew; allow the top centimetre of soil to dry between waterings. Apply a balanced liquid feed every two to three weeks once flowering begins. Deadhead spent blooms promptly — or cut flowers for the vase — to stimulate continuous bud production. Tall varieties (above 60 cm) may need light staking in exposed positions. Pinch growing tips when plants are 10–15 cm tall to encourage bushy branching.

Harvest

Cut stems when the central floret is fully open and petals are firm; flowers cut at this stage last longest in the vase. For ongoing bloom production, harvest every few days before petals start to drop. The harvest window extends from first flowering until frost kills the plant — typically a 60-day period. Allow the last blooms of the season to set seed on the plant if you wish to save open-pollinated varieties for the following year.

In the kitchen

Zinnia petals are edible and mildly flavoured, suitable for scattering over salads, floating on drinks, or using as a colourful garnish on desserts and canapés. Larger blooms make striking edible decorations on celebration cakes. Use petals freshly picked for the best colour and texture.

Storing

Fresh-cut stems last 7–10 days in a clean vase of cool water; re-cut the stem ends at an angle daily and change the water every two days. Dried flowers retain colour well — hang stems upside down in a warm, airy space for two to three weeks. Saved seeds should be stored in a sealed paper envelope in a cool, dry place and will remain viable for two to three years.