Keep on watering, watering, watering, but try to water the soil and not the heart of the plants.
They will grow a lot in the next few weeks and the stems at the centre will be tender. There seems to be a lot of waste outside leaves. Mostly I have found it difficult to produce much that is edible raw, but it is fine for cooking.
Their peak will probably be the end of September. You must finish them before the first sharp frost.
Oh yes, they do like plenty of water.