From what little I know apart from that they are a short-lived perennial and they suffer badly from rust, I would plant them out now. They don't like their roots disturbed as more mature plants.

Hollyhocks don't mind dry soil and hot temps... I can overwinter them in my climate which is very cold in winter. They seem indifferent to the soil they're in but like lots of sun. As to water, I've seen them grow along the margin of a disused parkinglot in a city. growing in gravel and direct sun with drainage like that they probably have a huge root system and will grow to 8-10 ft. tall. The tallest clump I've managed was on the edge of an old driveway from seeds dropped by mistake while hunting for more commodious spots to plant. I have pics on my GoY page from last summer. They are one of my favourites and seem to like the society of rudbeckia. I have both. they're biennial so second year plants will flower the best.