Growing horseradish from roots/thongs is incredibly easy. We’d recommend growing it in pots as it tends to spread and take over, so it’s easier to keep it contained! Choose something that is nice and deep, and aim to plant 2-3 ‘thongs’ in a 30cm wide pot.
Fill the pot with multipurpose compost and use a dibber to make 2 or 3 deep vertical holes. Drop one thong into each hole (sorry if this is sounding a bit weird!) You ideally want the top of each thong to sit 5-6cm below the surface of the compost. Then cover them with compost, water the pot and let them grow!
Keep them watered, particularly during dry spells, and if you notice any rotting/dying leaves then cut them off. Other than that, there is very little to do until they die back in autumn. Wait until the first frosts (to add flavour!) and then you can harvest your horseradish roots. Te best way to do this is to turn the pot upside down and then fish out the roots that you want to use. Then replant the others. Doing this will prevent the horseradish from outgrowing its pot.