Give the potted mums plenty of water, especially if they're in the direct sun. They like that.
If you're going to plant them in the ground, wait until spring; planting them now gives them a 50-50-chance of surviving the winter at best, even with a good mulch. You can overwinter them in the pot in a cool spot in an unheated porch, basement or garage, where they won't freeze but will still stay cool. Don't cut back the dead stems just yet. Then you can plant them in the spring, and cut the dead stuff off -- don't pull or tug -- as you plant. Give them a little fertilizer, and lots of water at first.
As they send up new stems in the spring, begin to pinch the stems off about an inch or so every so often to encourage branching. My mom says to do this until the Fourth of July
, but I keep pinching them back until August to delay flowering until late September. Mums will bloom in August if you let them go -- they'll also flop over.
But since I'm a couple of hardiness zones south of you, maybe pinching only through early July would work best for you.
And next fall, when they start to bloom, keep pinching off the faded flowers. That will encourage a longer bloom time.
Good luck, and congrats on your house!
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