How Much Cold Can a Dill Plant Stand?

Life Span

• Dill grows best from directly sown seed in full sun and well-drained soil, germinating in seven to 14 days at air temperatures of 60 to 68 degrees. Figure on about six weeks to harvest flowerheads gone to seed, although you can begin snipping leaves, or "dillweed," as soon as development is under way. Regular pruning helps plants bush out. Leaves reach peak flavor when flowering starts. Clip bud discs promptly to keep leaf production going or allow plants to fully bloom, shutting down leaf formation as energy is transferred to forming seed heads.

Extend the Harvest

• Sowing multiple crops -- every couple of weeks at the start of growing season -- ensures an ongoing supply of leaves, flowers and seeds. Longer, warmer summer days boost plant oils and flavor. In frost-free areas it’s possible to grow dill year-round. But sustained temperatures of 95 degrees or above cause seed production to dwindle as plants bolt. In intense-heat environments gardeners may plant dill seeds every two weeks in spring after the danger of exposing emerging seedlings to frost is over and plant again in fall when temperatures moderate.

Growing Tips

• If you amend soil at sowing time with 2 inches of organic compost, there’s no need for additional feeding. For container-grown dill use potting soil that contains fertilizer for container-grown dill or fertilize once monthly with an all-purpose water-soluble plant food at the rate of 1 tablespoon per gallon of water. Dill aren’t super thirsty; a once- or twice-weekly soaking is fine for growing plants and less if they have already gone into the end-of-life flowering stage. Dill grown outdoors has a stronger flavor.

  Frost advisories are issued when temperatures in the mid-30s or lower are predicted. Weather announcers and meteorologists use the term "killing frost" to indicate sustained cold below the 32-degree freezing point that will either end or delay growing season. Bring still-producing dill plants indoors if you want to keep them alive or harvest the remaining leaves. Seeds won't be affected by the cold.

Varietal Options

• Dill is no shrinking violet. The statuesque Mediterranean and South Russia native thrives in U.S. Department of Agriculture plant hardiness zones 3 to 11, typically averaging 24 to 36 inches tall at maturity. Take care to position your dill where nearby flowers and foliage won’t be overshadowed. Available cultivars include “Fernleaf,” a slower-to-bolt dwarf variety that maxes out at 18 inches tall; “Superdukat,” which is also slower to bolt; and “Mammoth,” favored by commercial producers. "Bouquet" is preferred for cut flowers.