Dill leaves taste better picked just before flowers form. Start picking the fresh leaves as soon as they're big enough to use. Pick them early in the morning or late in the evening, clipping them close to the stem.
If you prefer to harvest dill seed, allow the flowers to form, bloom and go to seed. Cut the seed heads when most of the seeds have formed -- about two to three weeks after the blossoming starts.
Hang the seed heads upside down by their stems in a paper bag. The seeds will fall into the bag when they mature and dry out.
Store Dill in Fridge
Freshly picked dill leaves have the best flavor. However, they keep for several days in the refrigerator. Put their stems in a jar of water and cover the leaves with a plastic bag.
They store for several months if you layer them with pickling salt in a covered jar in the refrigerator. When you are ready to use the leaves, simply wash them and use them as fresh.
There are several ways to store dill longer-term. Dry it by hanging bunches of stems upside down in a dark, dry, airy place until they're crumbly. Store them in a tightly sealed jar away from light, and use within six months. Or use a food dehydrator.
Freeze dill by cutting the leaves, long stems and all, into sections short enough to fit into plastic bags. Don't chop the leaves into bits, or they'll lose fragrance and flavor. They'll keep in the freezer for six months.