When to Plant in Delaware: Vegetable & Flower Planting Calendar
Delaware is small but not uniform: northern New Castle County (Hockessin, the Piedmont hills) tends to frost later in spring than coastal Sussex County, where the Atlantic and the Delaware and Chesapeake Bays moderate temperatures. Use this guide to time seed-starting, transplanting, and fall planting around your local frost dates. Delaware falls in USDA zones 7a–7b; average last spring frost runs from early to mid-April, and first fall frost from late October to early November.
About these dates: Timings are counted from your average last spring frost date, which is only an average — a frost can still occur after it. Dates vary within a state by elevation, distance from water, and microclimate. Look up the frost date for your ZIP code (your state Cooperative Extension office or NOAA climate normals are good sources) and adjust for the current season’s weather and soil temperature.
Delaware frost dates by region
| Region | Typical average last frost | USDA zone (approx.) |
|---|---|---|
| Northern New Castle County (Piedmont) | Often mid-to-late April | 7a |
| Central (Kent County, Dover area) | Around mid-April | 7a–7b |
| Coastal Sussex County | Early to mid-April | 7b |
Planting calendar for Delaware
Find your local last-frost date, then count forward or back using the table below.
| Crop | When to plant (relative to last frost) | Notes |
|---|---|---|
| Peas | Direct sow 4–6 weeks before last frost | Tolerates light frost; sow when soil is workable |
| Spinach | Direct sow 4–6 weeks before last frost | Also sow 6–8 weeks before first fall frost |
| Lettuce | Direct sow or transplant 2–4 weeks before last frost | Bolts in heat; succession sow; fall crop too |
| Radishes | Direct sow 2–5 weeks before last frost | Fast (3–4 weeks); sow again in late summer |
| Kale | Start indoors 8–10 weeks before; transplant 2–4 weeks before last frost | Sow again 8–10 weeks before fall frost; frost sweetens leaves |
| Onions (sets/transplants) | Plant 2–4 weeks before last frost | Choose day-length type suited to your latitude |
| Potatoes | Plant 2–4 weeks before last frost | Soil about 45°F+; hill as plants grow |
| Broccoli | Start indoors 8–10 weeks before; transplant 2–4 weeks before last frost | Cool-season; harden off; good fall crop |
| Cabbage | Start indoors 8–10 weeks before; transplant 2–4 weeks before last frost | Cool-season; harden off; good fall crop |
| Tomatoes | Start indoors 6–8 weeks before; transplant 1–2 weeks after last frost | Wait for nights reliably above 50°F |
| Peppers | Start indoors 8–10 weeks before; transplant 2–3 weeks after last frost | Need warm soil (65°F+) |
| Eggplant | Start indoors 8–10 weeks before; transplant 2–3 weeks after last frost | Need warm soil (65°F+) |
| Beans (bush & pole) | Direct sow 1–2 weeks after last frost | Seeds rot in cold, wet soil |
| Sweet corn | Direct sow 1–2 weeks after last frost | Soil 60°F+; plant in blocks for pollination |
| Cucumbers | Direct sow 1–2 weeks after last frost | Frost-tender; watch for cucumber beetles |
| Squash | Direct sow 1–2 weeks after last frost | Frost-tender; watch for squash vine borer |
| Pumpkins | Direct sow 1–3 weeks after last frost (count back ~90–120 days from target harvest) | For October pumpkins, many sow in late May–June |
| Basil | Start indoors 4–6 weeks before; transplant 1–2 weeks after last frost | Very cold-sensitive |
| Marigolds | Start indoors 4–6 weeks before or direct sow after last frost | Easy warm-season annual |
| Zinnias | Start indoors 4–6 weeks before or direct sow after last frost | Easy warm-season annual |
| Tulips | Plant in fall when soil cools below ~60°F | Typically around first fall frost, before ground freezes |
| Daffodils | Plant in fall when soil cools below ~60°F | Slightly earlier than tulips is fine |
| Garlic | Plant cloves in fall, a few weeks before the ground freezes | Harvest the following early summer |
Tips for Delaware gardeners
- Watch soil temperature, not just the calendar — warm-season crops stall in cold soil. An inexpensive soil thermometer helps.
- Harden off transplants over 7–10 days before planting out.
- Plan a fall garden: count back from your first fall frost to sow lettuce, spinach, kale, and radishes in late summer.
- Keep weeds down early — see our weed identification guide.
Frequently asked questions
When is the last frost in Delaware?
Average last spring frost in Delaware ranges from early to mid-April, depending on location. Check the average for your ZIP code, and remember frost can occur after the average date.
What USDA zone is Delaware?
Delaware spans roughly USDA hardiness zones 7a–7b on the 2023 USDA map. Hardiness zones describe winter low temperatures, not frost dates.
When can I plant tomatoes in Delaware?
Transplant tomatoes outdoors about 1–2 weeks after your local average last frost, once nights stay above about 50°F. Start seeds indoors 6–8 weeks before the last frost.
Other Mid-Atlantic planting calendars
Maryland · Pennsylvania · New Jersey · Virginia · All states