When to Plant Blueberries in New Castle County, DE
Blueberries are long-lived shrubs producing sweet, antioxidant-rich berries. They require acidic soil and are attractive ornamental plants with fall color and spring flowers.
New Castle County, Delaware is in USDA Zone 7a. The average last spring frost is April 6 and the first fall frost is October 31, giving you a growing season of approximately 208 days.
At an elevation of 415 feet, New Castle County receives approximately 38.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Blueberries during the growing season.
New Castle County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-7.1
Drainage
Well Drained
Plant Planting Risk Windows
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.
Soil Compatibility in New Castle County
How your county's soil matches Blueberries's growing requirements.
Soil pH
Your soil pH (5.2–7.1) is more alkaline than Blueberries prefers (4.5–5.5). Add sulfur or peat moss to lower pH.
Soil Texture
The silt loam soil in New Castle County is excellent for Blueberries — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Blueberries.
How to Plant Blueberries
How Much Blueberries to Grow
For a family of 4, plant approximately 8 blueberries plants in about 192 sq ft. In New Castle County's 208-day season, you'll have plenty of time for a full harvest. Plan your garden layout →
Plant Water Budget
Monthly Watering Guide for Blueberries
Blueberries needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Blueberries Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.4" | 0" | ❄️ Dormant |
| Feb | — | 2.7" | 0" | ❄️ Dormant |
| Mar | — | 3.4" | 0" | ❄️ Dormant |
| Apr | 5.2" | 3.2" | 2" | 💧 Light watering |
| May | 5.2" | 3.3" | 1.9" | 💧 Light watering |
| Jun | 5.2" | 3.3" | 1.9" | 💧 Light watering |
| Jul | 5.2" | 4.1" | 1.1" | 💧 Light watering |
| Aug | 5.2" | 3.2" | 2" | 💧 Light watering |
| Sep | 5.2" | 3.1" | 2.1" | 💧 Light watering |
| Oct | 5.2" | 3.2" | 2" | 💧 Light watering |
| Nov | — | 3.4" | 0" | ❄️ Dormant |
| Dec | — | 2.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in New Castle County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Blueberries Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Blueberries Planting Timeline — New Castle County, DE
Blueberries Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 27 | Apr 27 – May 11 |
· 48" apart · Rows 72" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · 1-2 times/week
📅 Days to Maturity
730–1095 days
🧪 Soil pH
Needs 4.5–5.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
208 days in New Castle County
Growing Tips for Blueberries in New Castle County
Direct sow Blueberries outdoors after April 06 in New Castle County when soil has warmed and frost danger has passed.
Your 208.0-day growing season in New Castle County is tight for Blueberries (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
Plant at least two varieties for cross-pollination. Acidify soil with sulfur or pine needle mulch to maintain pH 4.5-5.5. Protect ripening berries from birds with netting.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Blueberries in Other Locations
Frequently Asked Questions
When should I plant Blueberries in New Castle County, DE?
New Castle County is in Zone 7a with an average last frost of April 6. Plan your Blueberries planting based on this frost date — see the calendar above for exact timing.
What planting zone is New Castle County, DE?
New Castle County, Delaware is in USDA Hardiness Zone 7a. The average last spring frost is April 6 and first fall frost is October 31.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help New Castle County gardeners in Zone 7a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.