Technically, you can grow from seed as you would if you grow carrots, but horseradish needs a long growing season. In most areas, it wouldn’t be ready for harvesting at the right time if started from seed, even early. If you try, use organic pots you can transplant directly into the ground so as not to interfere with developing roots. In most cases, it is easier to start horseradish from plants, thongs or cuttings, as outlined above.