Celery: Sowing, planting and harvest calendar

First check which celery you have: stalk celery, celeriac or cutting celery. Choose the packet's sowing period in relation to your growing season and the time needed to raise plants. Sowing under cover gives this slow crop a head start before outdoor conditions are warm enough. Use a clean seed tray or modules with drainage holes, filled with fine seed compost that you have already moistened.

Scatter the tiny seeds thinly over the surface. They need light to germinate, so press them gently into place. If the packet recommends covering them, use only a very light dusting of sieved compost. Keep the tray somewhere bright with steady warmth of at least 15°C. Maintain moisture without saturating the compost and ventilate any clear cover. Germination can be slow and uneven.

Once seedlings appear, provide plenty of light and protect them from chilling: prolonged exposure to low temperatures can encourage premature flowering later. Pot them on when they have several true leaves and are easy to handle, keeping one seedling per module. Leave the central growing point clear. Grow them on under cover before gradually hardening them off for planting outdoors.

Outdoor celery sowing is most suitable where the mild growing season is long. This crop grows slowly, so plants raised under cover are often a better choice in a short season. Check your celery type and the packet's instructions. Wait for warm soil and settled frost-free conditions; a calendar month alone is not a reliable guide. Young plants exposed to prolonged cold may flower prematurely later.

Prepare a small, weed-free patch with a fine, level surface in fertile soil that retains moisture without staying saturated. Moisten it before sowing. Scatter the seeds very thinly on the surface and press them gently into contact with the soil: they need light to germinate. If the packet advises covering them, use only a light dusting of fine soil. Mark the rows so you can find this sometimes slow-emerging crop.

Water with a fine spray without shifting the seeds. Watch for surface drying, especially in wind or sunshine. Once seedlings have several true leaves, thin or transplant them carefully. Set the final spacing according to whether you are growing stalk celery, celeriac or cutting celery, and follow the variety's guidance rather than using one density for every type.

Use well-rooted celery plants with several true leaves. Check whether they are stalk celery, celeriac or cutting celery. Gradually harden off plants raised under cover, then wait until frost has passed and conditions are reliably mild. Prolonged chilling of young plants can cause premature flowering later, even if they survive the initial planting.

Choose fertile soil that holds moisture without staying waterlogged. Weed and prepare planting holes before removing the plugs from their containers. Water the rootballs, ease them out carefully, and plant without damaging the roots. Keep the central growing point clear and maintain the previous growing level. With celeriac, the stem base should sit at soil level rather than being buried.

For modern stalk celery grown in blocks, about 23 to 30 cm between plants is a useful starting point, adjusted to the variety. For celeriac, allow about 30 cm between plants and 40 to 45 cm between rows. Follow the label for other forms. Firm gently, water thoroughly, and check moisture during establishment. A suitable temporary cover can help if weather turns cooler; also watch for slugs around the young leaves.

Choose your harvesting method according to the celery type. For stalk celery, wait until the stalks are a useful size, firm and still tender. Take a few outer stalks with a clean tool while preserving the heart, or harvest the whole plant. Avoid waiting until the leaves yellow and the stalks become very stringy. Timing depends on variety and climate; many modern varieties need harvesting before hard frost.

For cutting celery, pick small amounts of leaves and leaf stalks as needed, leaving foliage and the central growing point intact. For celeriac, judge the development of the swollen base instead. Lift the plant with a fork inserted far enough away to avoid damaging it. Celeriac can stay in the ground over winter where conditions allow, but frozen or waterlogged soil and severe cold affect that decision.

Discard damaged material and refrigerate harvested stalks and leaves for prompt use. Wash them before eating. To store celeriac, remove the foliage and keep sound swollen bases in a cool, frost-free place, surrounded by a suitable medium that reduces drying. Check their condition regularly instead of relying on a fixed storage period. Handle each harvest gently to avoid bruising.