Starting from seeds:
Timing: Aim to sow seeds indoors around mid-March to early April.
Preparation:
Fill seed trays, modules, or pots with moist seed compost.
Consider soaking the seeds in warm water overnight to expedite germination.
Sowing:
Sow seeds thinly and barely cover them with fine vermiculite or sieved compost.
Place the trays in a warm propagator or cover them with a clear plastic bag to maintain warmth (at least 15°C or 59°F).
Be patient, as germination can take up to three weeks.
After germination:
Provide the seedlings with plenty of light and water regularly.
Maintain temperatures above 10°C (50°F) to prevent bolting (premature flowering).
Transplanting:
Timing: Wait until the danger of frost has passed and nighttime temperatures consistently stay above 10°C (50°F).
Soil:
Choose a location with full sun and well-drained, fertile soil rich in organic matter.
If needed, amend the soil with aged manure, compost, or a balanced fertilizer like 5-10-10.
Aim for a soil pH between 5.8 and 6.8.
Planting:
Harden off the seedlings by gradually exposing them to outdoor conditions for a week before transplanting.
Plant celery in a block formation with 23cm (9in) spacing between each plant. This helps shade the stalks and promotes blanching.
Alternatively, plant in a large container using a similar spacing and multi-purpose compost.
Ongoing care:
Water regularly and deeply, aiming to keep the soil consistently moist but not soggy. Celery thrives in moist conditions similar to its boggy origins.
You can help blanch the stalks (lighten their color and improve tenderness) by earthing up the soil around the base of the plants as they grow.
Feed the plants with a liquid fertilizer every two to three weeks during the growing season.
Be attentive to potential pests and diseases such as aphids, celery leaf spot, and blight.
Harvesting:
You can start harvesting individual stalks as needed once they reach a mature size, typically around 3-4 months after transplanting.
To harvest the entire plant, cut the stalks at their base just below the soil level.
By following these steps, you can enjoy growing your own fresh, crisp celery at home.