How to Grow Dill

Where and when to sow

Dill wants full sun and well-drained soil of average fertility. It does not need rich ground: Utah State advises no more than 1 inch of compost per 100 square feet and no extra fertilizer if the bed was amended at planting. NC State notes that it prefers slightly acidic soil and grows best around 70°F, and that too much water or shade produces lanky plants that flop.

Sow directly in the garden. Dill’s long taproot makes it a poor transplant, and it grows so quickly from seed that transplants offer little advantage. Illinois, UW-Madison and NC State recommend sowing a week or two before the last spring frost; the University of Maryland waits until frost danger has passed. The dates for your zone above cover both.

Cover seed lightly, about ⅛ to ¼ inch deep. NC State notes that dill seed needs light to germinate, so do not bury it. Expect seedlings in 10 to 14 days (UW-Madison, NC State), or anywhere from 7 to 21 days depending on soil temperature (Utah State).

For a continuous supply of leaves, keep sowing while the weather is cool. Advice on the interval varies widely: every 10 to 14 days (UW-Madison) or every two weeks (Illinois), every 2 to 4 weeks (NC State), or every 4 to 6 weeks (Utah State). Utah State adds that short rows, 2 to 3 feet long, planted regularly supply plenty for daily use, storage and seed. Late-summer sowings give a fall crop because dill tolerates light frost, and UW-Madison says seed sown in late fall can sprout the following spring.

Regional notes

• Cold North and mountain West: spring sowings around the last frost, with a late-summer sowing for fall. Utah State describes dill as quite hardy.
• Florida and the Gulf Coast: UF/IFAS recommends sowing September through December, with spring also possible, and names ‘Long Island Mammoth’ as the variety that does best in Florida. The Galveston County AgriLife office lists October as a good month to plant.
• Desert Southwest: University of Arizona Extension in Tucson gives October to November and February to April. The Yuma County calendar runs plantings from October to February, with harvest in February and March.
• California: UC Cooperative Extension Sacramento notes that, like cilantro, dill bolts quickly in hot weather, so harvest leaves before bloom.

Thinning, spacing and support

Thin seedlings when they are 3 to 4 weeks old. Recommended spacing ranges from 3 to 6 inches (UW-Madison) to 9 inches with rows 12 inches apart (Utah State) and 12 inches (Texas A&M AgriLife). Wider spacing suits seed crops and big varieties; thinning matters either way, since Utah State lists crowding as a cause of early bolting.

Keep the bed weeded. UW-Madison notes that dill competes poorly with other plants. Tall varieties, which can reach 4 feet or more, benefit from staking or a spot out of the wind, because the hollow stems are easily broken by wind, rain and hail.

Watering

Water consistently. NC State says steady moisture helps prevent bolting. Utah State says established dill is not a big water user and typically needs one or two irrigations a week, and it warns that overwatered plants are prone to powdery mildew. Dill tolerates drier soil once seed has set.

Varieties

Extension services divide dill into seed types and slow-bolting leaf types, plus compact varieties for containers.

• For leaves: UW-Madison lists ‘Fernleaf’ (compact, slow to bolt, a 1992 All-America Selections winner), ‘Hercules’, ‘Teddy’ and ‘Szmaragd’ as slow-bolting. NC State calls ‘Fernleaf’ the slowest to bolt and ‘Hera’ slower than many. Utah State recommends ‘Dukat’ or ‘Tetra’ for a long supply of leaves, and Illinois lists ‘Green Sleeves’ as resistant to bolting.
• For seed and pickling: ‘Long Island Mammoth’ (NC State, UF/IFAS for Florida) and ‘Bouquet’ (UW-Madison, NC State), which produces both leaves and large seed heads.
• For containers: ‘Fernleaf’, ‘Ella’ and ‘Monia’ (Illinois, UW-Madison).

In containers, use a deep pot to fit the taproot; a UC Master Gardener chart gives 12 inches as the minimum soil depth. Tall types may need staking even in pots.

Harvesting leaves, flowers and seed

Cut leaves any time after plants are a few inches tall, until the seed stalk forms. Regular cutting helps delay flowering. Utah State says leaves are generally ready 6 to 8 weeks after sowing, and it says flavor peaks just as the flowers begin to open. Cut individual leaves at the stem, or cut whole stems a few inches above the ground and discard the thick, tough parts.

Fresh dill wilts quickly but keeps about a week in a plastic bag in the refrigerator. Freezing preserves flavor better than drying, which costs much of it quickly. For pickles, Utah State suggests using the whole plant: stems, leaves, flowers and seeds.

Seed ripens about 2 to 3 weeks after the blossoms appear (Illinois). Ripe seed shatters easily, so timing matters. NC State says to harvest as the stems start drying and the seeds turn golden brown; UW-Madison says to cut heads once the seeds are fully developed but before they turn brown. Dry them in a paper bag in a warm, dry place for about a week before separating the seeds. Stored airtight in a cool spot, seed stays viable for several years, according to UW-Madison.

Problems

• Black swallowtail caterpillars. The black, green and yellow larvae can strip a plant, often feeding in groups. UW-Madison says you can pick them off, but most people let them grow into butterflies; Utah State asks gardeners to leave them. Sow extra dill.
• Aphids. These show up as plants flower and seeds ripen (Utah State). Dill’s flowers also attract hover flies, whose larvae eat aphids, along with lacewings and lady beetles, so beneficial insects often keep them in check.
• Powdery mildew. It is more likely on overwatered plants. Water at the base and avoid overwatering.
• Blight and aster yellows. NC State notes these can cause significant damage. Remove affected plants.
• Unwanted seedlings. Dill self-sows freely. Deadhead flowers you do not want for seed.

NC State calls dill a good companion for cucumbers and broccoli and says planting it close to carrots can reduce carrot yield. That is long-standing gardener tradition rather than tested advice.