Northern & Central Midwest
Check for Pests Daily
Pests are coming, so get out into the garden daily. This will go a long way to preventing population explosions. When you see cucumber beetles, keep a watch for bacterial wilt and dispose of any plant that shows signs. When you see squash bug eggs (orange-red), dispatch them with your thumbnail.
Make sure to provide a sturdy trellis for cucumbers so they will ripen clean and hang straight. Cucumber fruits in contact with the soil are prone to rotting. Allowing them to climb a wood and chicken wire lean-to will allow you to plant lettuce underneath in the shade.
Don't Fertilize in Times of Stress
Hold off on fertilizing when it's hot and dry. Adding fertilizer, including compost and composted manure, will actually further stress plants and may cause tissue burn. And plants that are in a near-dormant state will not use any fertilizer you apply.
Snip Herbs Regularly
Keep snipping herbs to keep the plants full and producing. Use the snippings fresh in cooking, dry them, or freeze them using an appropriate method. Try to harvest before the plants blossom, and if they do begin to flower, pinch out the flower heads for more flavorful herbs.
Check Rain Barrels
Keep an eye on rain barrels or any other containers that hold water. Either drain regularly or flush with fresh water periodically to keep algae and other problems at bay. Make sure any holes have screening on them to prevent providing a nursery for breeding mosquitos.