Harvesting herbs throughout the summer to get the best flavor.
Harvesting herbs are slightly different from harvesting vegetables and fruit. For vegetables such as tomatoes and peppers we harvest the fruit of the plant; for carrots and potatoes we harvest the roots; but when harvesting herbs, particularly in large quantities for preserving, we are usually referring to the leaves. For small quantities to use in the kitchen, you can pick herbs throughout the growing season, but when you intend to preserve the herbs for winter use, you need to look at the optimum time when the important oils are at their best. This will depend on the specific herb.
Cilantro which grows easily from seed but goes to seed very quickly is probably not a good herb to dry for the winter. Rather than try to preserve the leaves, sow a few every week or two for continual harvest, and let them go to seed. Harvest the seed, which is the spice coriander, and use in salad dressings, crushed directly onto salads, or use to make a curry powder, along with cumin, cardamom, chilies and garlic.
For herbs that flower in the summer months, such as mint, harvest the leaves before the flower is set. Remember, too, with mint, not to let the plant go to seed otherwise, you will find lots of little mint plants taking over your garden next year. Other herbs that need harvesting over the summer months are sage and thyme, both of which flower in early summer but put on fresh new growth until fall. Chives put out an early flower too, which can be picked and preserved. Trim the chives back after flowering to encourage new growth which can then be harvested throughout the summer months. Rosemary flowers even earlier than chives, and as it is usually grown in a greenhouse in the northern zones, the flowers brighten your late winter days. The oils in rosemary are so strong that this herb can be harvested at any time, including when it is in flower.
Basil flowers in mid to late summer and should be harvested before the flowers bloom, to get maximum oils. Garlic chives are one of the latest herbs to flower, doing so as late as October in many areas. This herb can be harvested right up until the flowers bloom. Garlic chives are another herb that should not be allowed to go to seed, as it is very difficult to eradicate from the grass. Parsley is one of the few common herbs that will not flower the first year, but as a biennial, it will flower the spring of year two. Harvest parsley during its first year of growth.
So although there is a mad dash before the frost to gather as many herbs as possible, the best time for harvesting herbs is not when frost is looming, but rather on those cool summer mornings when they are at their peak. Harvesting herbs this way will give you plenty for preserving and for use throughout the winter months, and allow you to concentrate your efforts on gathering the last green tomatoes before the frost arrives.