When you are ready to harvest, choose a dry day and pick after the dew has dried. The essential oil concentration is said to be highest in the morning. Remember, essential oils give the plant its fragrance, flavor, and any health benefits that may be attributed to the herb. Because the oil content is higher in a plant before flowering, many herb gardeners recommend picking before the plant flowers. But I’ve harvested at all stages of growth. The best way is to experiment with different times. You might prefer the more delicate flavor of small, new leaves, especially for the more pungent herbs.
The easiest way to clean herbs for harvesting is to rinse them off with a garden hose. Make sure your hose is set to a light spray or mist; you don’t want dirt splashing up onto the plants. Soak them well and let them dry in the sun before you harvest. If you choose instead, to rinse them after cutting, use a salad spinner to remove the excess water.