If you must substitute, see below:
Dill seed is not a good substitute for fresh dill weed because of the difference in flavor strength but it does depend on the recipe. The seed has a camphorous, slightly bitter flavor, and the weed has a delicate flavor. The differences are like night and day.
Do you know how much dill seed is equivalent to one head of fresh dill?? I am going to make pickles, and fresh dill is not available. Thanks in advance for your help. – Judith Cartwright (8/22/01)
3 heads dill = 1 tablespoon dill seed
1/2 ounce dill seed = 1/2 cup fresh dill
3- to 5-inch sprig of fresh dill = 1/4 teaspoon of dried dill weed.
Young dill plants that you thin from the garden are ideal to chop for tender, fresh dill weed. Although you can trim dill foliage at any time to use fresh, the leaves have the best flavor just before the umbrels bloom. Trimmed dill continues to grow new leaves until the plant blooms, so you can repeat harvest the foliage.
Shake the dry dill seeds from the stems into a bowl, sorting out the stems for disposal. Store dried dill weed and dill seeds in airtight containers in the cupboard.
Harvest dill seeds from mature plants after the flowers set seeds. The flower umbrels become clusters of seeds that cling to the plant until they are completely mature. Snip off the seed heads when the seeds are brownish and dry before the seeds scatter. Hold a bag or large bowl under the heads and snip – let the seed heads drop into the container.
Wash fresh dill weed and drain it dry, chop it, then freeze it in small containers or freeze it flat on a baking sheet to transfer to small containers. To dry dill weed, loosely tie together a few branches at the base with string or a rubber band and hang the bundles upside-down in an airy location out of direct sun. Bruising the branches can cause spots of decay or mold, so handle the dill gently. You can also use an electric dehydrator to dry dill weed quickly. A dehydrator helps the dried leaves retain the bright green color of fresh dill.
Common dill (Anethum graveolens) has naturalized in North America after its introduction from its native southwestern Asia. Dill is easy to grow, lending textural visual interest to the garden with its 3- to 4-ft tall, feathery foliage and 6-inch wide umbrels of bright yellow flowers. Dill foliage is food for black swallowtail caterpillars, so it is recommended as a host plant in butterfly gardens. But dill really shines in the kitchen. The sweetly pungent flavor is concentrated in both the leaves and the seeds, making dill a popular herb for a wide range of culinary uses. Dill weed is simply another name for dill foliage.