I have this happen all the time. I keep the plants in their original containers in light shade. Make sure they don't dry out. Water them frequently especially during hot periods.

If the pots are tiny, I'd plop them in larger pots until planting time.

Ditto NHBabs' suggestion re the larger pots--give those healthy roots some acreage. Chances are they're healthy plants that need only moisture to keep them going until planting time. Stachys Helen von Stein (Lambs Ear "big ears"), Stachys Hummelo, and Nepeta Walkers Low are all doing fine in my garden beds.

Thanks! I think I'll follow this advice to put them in larger pots and keep them watered for a few weeks. The pots are 3.5 inches but the plants themselves have large and healthy adult leaves.