Early summer or late spring is a good time to cut back your rhododendrons. You can cut them to within 3 feet of the ground if you want to wait 3 years for renewal or cut them down by one third if you want them to look halfway decent as they recover. You should consider improving the soil with a wood chip mulch, watering more in summer and fall and feeding with a rhododendron and azaleas food in early spring. All will help green up the foliage and grow more leaves. Do not wait until autumn. Good luck and Keep growing, Marianne Binetti