You can plant lettuce, mustard greens, spinach, kale and radishes right now. They will either be ready for a fall harvest or will tolerate the winter’s cooler conditions and have a head start next spring.
"mustard greens"
Gardentalk – Preparing for early vegetable and garlic scape harvest
Master Gardener Ed Buyarski also recommends applying a liquid fertilizer to some vegetables if they turn a pale or yellowish-green.
Gardentalk – Second planting
Master Gardener Ed Buyarski encourages us to plant radish, kale, lettuce, spinach, and other vegetables for the remainder of the summer season.