Celeriac is forgiving in the ground long after other roots have come up, and a light frost even improves the flavour. The trouble is a hard freeze, which locks it in solid and can turn the roots to mush. Lift before that happens, trim and cure the knobbly roots properly, and they'll keep firm in a box of damp sand well into the leaner months.

Lift and Store Celeriac Before the Ground Freezes

What you need

1 wooden crate or sturdy box with gaps or holes for air
15 litres slightly damp sand or old potting compost for bedding the roots
1 sacking or hessian sack to cover the box loosely
1 bucket or trug for carrying lifted roots

Step by step

Push a garden fork into the soil about 15cm out from each plant, working right round it before levering gently upward. Stabbing straight down beside the stem risks spearing the bulb.
15 min
Lift the loosened root by hand, gripping the base of the leaf stalks rather than pulling on the leaves, which can tear away from the crown and leave the root behind.
10 min
Cut the top growth back to about 2cm above the crown with a sharp knife, then trim off the long straggly side roots, leaving the main knobbly body intact.
15 min
Brush off loose soil with your hand rather than washing the roots. Moisture left sitting on the skin is what starts rot in storage.
10 min
Spread the trimmed roots out somewhere cool, dry and out of direct sun for five to seven days, so the cut surfaces and skin toughen before they go into store.
5 min
Pack the cured roots upright in the crate so they aren't touching, filling the gaps with slightly damp sand or old compost until each root is covered.
15 min
Cover the crate loosely with sacking and move it somewhere cold and frost-free, such as an unheated shed, garage or cellar, rather than anywhere heated.
5 min

Afterwards

Wipe soil off the fork and knife before putting them away so they don't rust over winter. Check the stored box every two to three weeks and pull out any root that has gone soft or started weeping before it spreads to the others. Sound celeriac keeps this way for three to four months.

Questions

Can I just leave celeriac in the ground instead of lifting it?

In a mild winter with a thick straw mulch over the crowns, yes. But once the ground freezes hard you can't get a fork in, and a sustained freeze can turn the roots to mush, so lifting and storing is the safer bet anywhere frosts are more than occasional.

Why is my celeriac so knobbly and hard to peel?

That's normal — the knobbles are where side roots grew. Trim them off at harvest and again before cooking; a smoother-rooted variety next year will save some of the fiddling.

How long will stored celeriac actually keep?

Three to four months somewhere cold in damp sand, typically through to late winter, as long as you keep pulling out any root that softens.

Can I store it in the fridge instead of a shed?

Yes, if you don't have anywhere cold enough. Trim and cure it the same way, then keep the unwashed roots in perforated bags in the salad drawer.