Celeriac (also known by the botanical name Apium graveolens var. rapaceum) is not the easiest vegetable to grow; these plants have a long growing season and the seeds need to be started off in the warmth, fairly early in the season.  Celeriac seedlings will need to be protected inside a glasshouse, polytunnel, or conservatory, until all risk of frost has passed.  These seeds require consistently warm temperatures of around 18-21C (64-70F) for germination.  The assistance of a heated propagator and glasshouse make growing Celeriac easily achievable; these tools will enable gardeners to produce medium to large sized, very firm and dense, rounded Celeriac stems, with a distinctive celery-turnip flavour.

In the UK, we can sow Celeriac seeds from the beginning of March to the end of April (springtime).  You will need a heated propagator, along with a very light and bright place (a conservatory, porch, cold frame, polytunnel, or glasshouse is ideal) to grow Celeriac from seed.  It’s vital that these seeds receive sufficient light from above whilst the plants are growing; this will prevent the Celeriac plants from becoming leggy and flagging, or developing horizontal growth.  Plants that receive light shinning down onto them from above are encouraged to produce strong, vertical plant growth.

Over the years, I’ve tried and failed to grow strong and healthy Celeriac plants on a window sill; however, none of my windowsills are bright or sunny.  I have enjoyed growing Celeriac successfully when I’ve sown seed inside my glasshouse and then planted my Celeriac plants outdoors, in early summer.

Sow Celeriac seeds thinly in seed trays or modules filled with a good quality, peat-free compost.  Celeriac seedlings remain small and insignificant in their appearance for quite a while.  It’s really important to ensure your seedlings receive sufficient light, water, and warmth, while they’re growing.  Ensure night time temperatures never fall below 13C (55F).

Celeriac seedlings can be planted outside when all risk of frost has passed, which in the UK tends to be from the end of May through to the middle of June (depending on which area you garden in).  Take time to harden your Celeriac seedlings off before you plant them outside.  Hardening plants off may seem like a lot of hassle, but I can assure that it really is worthwhile; the small amount of extra time and trouble you take now will help your Celeriac plants acclimatise themselves and produce strong, healthy growth more rapidly.  Simply move your plants outside in the morning and then bring the seedlings safely back undercover in the evening.

To form good-sized, useable rounded stems, Celeriac plants must receive sufficient water at all stages.  It’s important to water your celeriac plants during times of drought and to provide your plants with enough water to sustain their growth and development.  Removing the outer leaves on Celeriac plants in late August and September is said to help increase the size of your eventual harvest and produce larger stems.  Celeriac are usually ready to harvest from mid September onwards.  These mature vegetables can be left in the ground and harvested as required, during autumn and winter; Celeriac also keep well after harvesting and will last for at least a few weeks in the fridge or pantry.

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Articles that mention Celeriac:

• May. 2022 – Celebrating Climbing Runner Beans
• Mar. 2022 – Cutting Celery
• Mar. 2018 – Peat Free Compost Trial 2017, Growing Carrots
• Nov. 2017 – Access Garden Products Classic Growhouses
• Nov. 2015 – Gardening Advice for Mid-February to Mid-March
• Nov. 2015 – Gardening Advice for Mid-March to Mid-April
• Feb. 2015 – February In The Garden
• Nov. 2014 – Garden Advice for mid-February to mid-March
• Nov. 2014 – Garden Advice for Mid-September to Mid-October
• Nov. 2014 – Gardening Advice for Mid-September to Mid-October
• Nov. 2014 – Gardening Advice for Mid-September to Mid-October