If you want to put your hoggs back to the tup in the autumn, yes I would put them into a yard with only some hay, or maybe even straw (and water of course), until the udders are soft and shrinking, and afterwards onto not so good grass (to prevent CCN).
Depending on how they look at the end of summer you may want to flush on good grass for a few weeks before tupping. I have found that with the Shetlands that is not necessary, but they are not lambed as hoggs.