For a plant that produces such chunky macho roots, celeriac requires surprisingly careful treatment to get going. The seeds are miniscule and have to be sown inside where it's warm and the fragile seedlings can develop away from the rigours of the veg plot.
Once established they toughen up. The wetter the weather the more they love it!
Time from seed to plate: 28 weeks
Sow celeriac as early as you can to give the plants plenty of time to mature before growth slows down in the autumn. The seeds need warmth to germinate, so they have to be sown indoors.
Our propagator kits with 'Jiffy 7' compost pellets are ideal for sowing. Soak sixteen pellets in water till they expand and sow 3-4 of the miniscule seeds into the top of each one. There's no need to cover the seeds because they need light to germinate. Put them in the propagator, cover, and place on a warm windowsill. Keep moist.
Within one or two weeks the seeds should sprout. Remove the propagator lid at this stage. If more than one seedling comes up in the same jiffy remove the weaker ones.
Growing method: Seed propagating kits then plant out in your plot.
Plant out in your plot in May when your celeriac is about 2in tall and the winter frosts have come to an end - that way they can establish themselves before the dry summer weather arrives.
Make sure the ground has lots of compost/manure dug in and position with 12in between plants. Get some organic slug killer down to protect them early on. Keep the plants moist- spreading a little extra manure around them in the summer to keep moisture in if the weather's really dry.
Start pulling your celeriac from October. For the best flavour, leave them in the ground right up until when you need them.
In very cold areas it's best to harvest all the roots before severe winter frosts arrive. Leave a few leaves and a layer of soil on the roots to keep the flavour in, and store somewhere cool and dry like a garage.
Down here in Devon where it's relatively mild I tend to leave mine in the soil.