Early autumn is a good time to give your celeriac plants a little bit of TLC – they’ll benefit from a feed and a bit of a trim to help them reach a good size for you to harvest in winter time.
As celeriac plants begin to mature and the bulbs start to swell (which usually starts to happen in early autumn) you can remove some of the outer leaves. Cut off any leaves that are shooting out of the side of the crown, or beginning to fall horizontal. You only need to leave 5 or 6 leaves. This will concentrate the plant’s energy into swelling the crown rather than producing foliage. Over the next few weeks, just cut off any side shoots that appear.
A liquid feed now will boost the nutrients in the soil and help the celeriac grow. It’s also worth weeding well now as you don’t want your celeriac to be competing for the nutrients – too much competition equals small celeriac bulbs!
In theory you can harvest celeriac from October onwards, but we find that, like parsnips, they are much tastier after a couple of frosts. And they usually need a little extra time to grow anyway.