Celeriac Not Swelling?

Celeriac is a shallow rooted and thirsty plant, and if it doesn’t get enough water during the growing season, it may not have started swelling at all, or may seem far too small.

The first thing to consider is when you planted out the celeriac – if it was before the end of June, then you would expect to see the roots begin to swell by September, and as long as they got enough water, sunlight and nutrition from the soil, they should be a harvestable size around about now (although you don’t have to harvest them – they will stand in the ground for several months, as long as you don’t have thousands of slugs looking for a snack.)

For those that were planted out later, you may not see much swelling just yet. Hang in there, as they still have time to plump out a little.

If you’re not seeing any swelling at all, then the chances are high that your celeriac plants didn’t get enough water during the summer months – they are incredibly thirsty plants, and since they are shallow-rooted, it doesn’t take much for them to run short on water during warm, dry spells. This may well have been the case with the heatwave we had in early autumn which would have hindered their swelling.

The other barrier to roots swelling is a lack of nutrients in the soil – celeriac loves a rich, compost heavy soil. Next time, try planting into a bed or planter with plenty of good quality compost – it would do well in one of our traditional crate planters filled with multipurpose compost, for example. Add a handful of wormcast fertiliser for good measure, keep the plants well watered during dry spells and you should get a good harvest next time.