The best time to harvest most herbs is just before they flower. At this time the leaves have the highest concentration of essential oils. Some herbs, such as basil, will respond by putting out a new flush of growth. Rather than picking off individual leaves, harvest entire stems right back to a set of leaves.
Visit the Garden Daily
Pest problems can really take off in the heat of summer. Try to visit your garden daily, inspecting plants for signs of insects or disease. Check the new growth and undersides of leaves where pests like to hide. Go out at dawn or dusk to catch slugs as well as fast-moving insects that slow down as the temperature cools. Carry a can of soapy water and brush or drop insects into it.
Harvest and Store Produce
Harvest frequently, even if you won't be using the produce right away. Stored in the refrigerator, vegetables like beans and peas keep for days, and by harvesting regularly you'll encourage plants to keep producing. Many crops can be quickly blanched and frozen with little loss of flavor and nutrients.
Continue making succession plantings to ensure a harvest well into autumn. If possible, plant cool-season crops like broccoli where they'll get a little shade from the hot afternoon sun. Plant another row of bush beans for late-summer harvest.
Rejuvenate Dry Container Gardens
If you come home to a dried-out container planting, don't despair. Some plants will wilt dramatically, but come back once moistened. If the water you add from the top pours right through, place the entire container in a saucer or tray of water and let the water soak into the soil from below. If it's still hot and sunny out, place the plant in a shady, cool spot for a few days. Remove damaged foliage and see if it develops new growth.