The heat is on! Now it's a matter of keeping plants hydrated.
One of the best things about Colorado gardening is the cool nights. The plants can de-stress and take up moisture. That's why it's ideal to water late in the day or early in the morning. The plants can go into the heat of the fully rejuvenated and hydrated.
It doesn't make sense to water during a hot day--unless it's an emergency--because of the high evaporation.
Never cut back iris leaves unless you're transplanting. The best time for this in after they bloom, so now is ideal.
Fork up a clump. Separate the pieces into individual "fans." Cut the fans back by about half. The reason for this is that the roots need to reestablish and they can't support all that top growth. Plant the rhizomes about an inch deep and keep them moist as they settle in.