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When to Plant Rosemary in Kent County, DE

Rosemary is an aromatic evergreen shrub with needle-like leaves and a piney, citrus flavor. It is a Mediterranean herb that thrives in warm, dry conditions.

Kent County, Delaware is in USDA Zone 7a. The average last spring frost is April 2 and the first fall frost is November 4, giving you a growing season of approximately 216 days.

At an elevation of 128 feet, Kent County receives approximately 47.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Rosemary during the growing season.

Kent County, DE (Zone 7a) Long season
216 days
Last Spring Frost April 2
216 growing days
First Fall Frost November 4

Kent County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Apr 4 🍅 Harvest: Jun 27 – Nov 14
Recommended (50%) ✗ May not fit
Transplant: Apr 9 🍅 Harvest: Jul 2 – Nov 19
Safe Start (90%) ✗ May not fit
Transplant: Apr 25 🍅 Harvest: Jul 18 – Dec 5

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Rosemary needs ~2,080 GDD — county provides 3,456 GDD Excellent fit

Rosemary Planting Timeline โ€” Kent County, DE

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors April 9 Apr 9 โ€“ Apr 23
Harvest July 2 Jul 2 โ€“ Nov 19

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May โ€”
June โ€”
July Harvest
August Harvest
September Harvest
October Harvest
November Harvest
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

80โ€“180 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 7a

Growing Season

216 days

Growing Tips for Kent County

Grow in well-drained soil and avoid overwatering. In cold climates, grow in containers and bring indoors for winter. Propagate from stem cuttings for faster results than seed.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Rosemary in Kent County, DE?

Kent County is in Zone 7a with an average last frost of April 2. Plan your Rosemary planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Kent County, DE?

Kent County, Delaware is in USDA Hardiness Zone 7a. The average last spring frost is April 2 and first fall frost is November 4.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Kent County gardeners in Zone 7a organize planting dates, track what's growing, and never miss a planting window.

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Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Kent County, DE. Local conditions may vary. Last updated: April 2026.