When to Plant Broccoli in St. Mary's County, MD
What to do in May
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
-
Begin indoor sowing: broccoli
Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.
June prep starts now
- First harvests: 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.
St. Mary's County, Maryland is in USDA Zone 8a. The average last spring frost is April 5 and the first fall frost is November 4, giving you a growing season of approximately 213 days.
At an elevation of 156 feet, St. Mary's County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 92°F, providing good warmth for Broccoli during the growing season.
St. Mary's County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.9
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 St. Mary's County
How your county's soil matches Broccoli's growing requirements.
Soil pH
Your soil pH (5.5–6.9) overlaps with Broccoli's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in St. Mary's County is excellent for Broccoli — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). 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 Aug 06 to harvest before frost.
For a dedicated fall crop, sow by Aug 26.
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 | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 3.3" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.3" | 1" | 💧 Light watering |
| May | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Jun | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4" | 0.3" | 💧 Light watering |
| Aug | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Oct | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Nov | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Dec | — | 2.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Nov in St. Mary's 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 — St. Mary's County, MD
Broccoli Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 1 | Mar 1 – Mar 15 |
| Transplant Outdoors | April 5 | Apr 5 – Apr 19 |
| Direct Sow | March 22 | Mar 22 – Apr 12 |
| Harvest | June 7 | Jun 7 – Jul 19 |
| Fall Sowing | August 26 | Aug 26 – Sep 9 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
213 days in St. Mary's County
Growing Tips for Broccoli in St. Mary's County
Direct sow Broccoli outdoors after April 05 in St. Mary's County when soil has warmed and frost danger has passed.
Summer highs in St. Mary's County reach 92°F — grow Broccoli as a spring or fall crop. Use shade cloth if planting in summer.
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.
Recommended Broccoli Varieties for St. Mary's County
Heat-tolerant broccoli — plant as early spring or fall crop
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 St. Mary's County, MD?
St. Mary's County is in Zone 8a with an average last frost of April 5. Plan your Broccoli planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Mary's County, MD?
St. Mary's County, Maryland is in USDA Hardiness Zone 8a. The average last spring frost is April 5 and first fall frost is November 4.
Your St. Mary's County Garden Planner — Free
A 24-page printable planner built for St. Mary's County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.