When to Plant Broccoli in Knox County, ME
Your May planting checklist for Knox County, Maine
We've pulled the most time-sensitive tasks for Knox County, Maine this May and put them front and centre. Tackle them in order.
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Get broccoli in the ground
Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.
June will be here before you know it — start on
- Starting indoors: broccoli
Broccoli is a nutrient-dense cool-season crop that produces large central heads followed by smaller side shoots. It is one of the most popular garden vegetables.
Knox County, Maine is in USDA Zone 6a. The average last spring frost is May 2 and the first fall frost is October 12, giving you a growing season of approximately 163 days.
At an elevation of 408 feet, Knox County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Broccoli to ensure they mature before fall.
Knox County Soil Profile
Soil Type
Silt Loam
Soil pH
5.1-6.7
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 Knox County
How your county's soil matches Broccoli's growing requirements.
Soil pH
Your soil pH (5.1–6.7) is more acidic than Broccoli prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Knox County is excellent for Broccoli — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Broccoli.
Organic Matter
Organic matter is moderate (3.3%). Annual compost additions will help Broccoli.
How to Plant Broccoli
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Broccoli
Sow every 6.9 weeks. Last sowing by Jul 14 to harvest before frost.
For a dedicated fall crop, sow by Aug 03.
Plant Water Budget
Monthly Watering Guide for Broccoli
Broccoli needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Broccoli Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3.1" | 0" | ❄️ Dormant |
| Feb | — | 3.1" | 0" | ❄️ Dormant |
| Mar | — | 3.1" | 0" | ❄️ Dormant |
| Apr | — | 3.8" | 0" | ❄️ Dormant |
| May | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Jun | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jul | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Aug | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 3" | 1.3" | 💧 Light watering |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 3.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Knox County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Broccoli 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.
Broccoli Planting Timeline — Knox County, ME
Broccoli Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 28 | Mar 28 – Apr 11 |
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Direct Sow | April 18 | Apr 18 – May 9 |
| Harvest | July 4 | Jul 4 – Aug 15 |
| Fall Sowing | August 3 | Aug 3 – Aug 17 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 6a
📆 Growing Season
163 days in Knox County
Growing Tips for Broccoli in Knox County
Direct sow Broccoli outdoors after May 02 in Knox County when soil has warmed and frost danger has passed.
Common pests for Broccoli in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 6-8 weeks before last frost. Provide consistent moisture to prevent hollow stems. Harvest heads before yellow flowers appear.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 1/2 mile from other brassicas. Biennial — must overwinter roots.
Broccoli in Other Locations
Frequently Asked Questions
When should I plant Broccoli in Knox County, ME?
Knox County is in Zone 6a with an average last frost of May 2. Plan your Broccoli planting based on this frost date — see the calendar above for exact timing.
What planting zone is Knox County, ME?
Knox County, Maine is in USDA Hardiness Zone 6a. The average last spring frost is May 2 and first fall frost is October 12.
Your Knox County Garden Planner — Free
A 24-page printable planner built for Knox County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.