When to Plant Asparagus in Union County, NJ
Your May planting checklist for Union County, New Jersey
Here's what deserves your attention in Union County, New Jersey this month. Everything below is tailored to Zone 7a and timed around your local frost dates.
Asparagus is a long-lived perennial vegetable that produces tender spears each spring for 15-20 years once established. It requires patience but rewards with reliable harvests.
Union County, New Jersey is in USDA Zone 7a. The average last spring frost is March 29 and the first fall frost is November 12, giving you a growing season of approximately 228 days.
At an elevation of 814 feet, Union County receives approximately 49.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 93°F, providing good warmth for Asparagus during the growing season.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
4.8-6.5
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 Union County
How your county's soil matches Asparagus's growing requirements.
Soil pH
Your soil pH (4.8–6.5) is more acidic than Asparagus prefers (6.5–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Union County is excellent for Asparagus — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Asparagus.
Organic Matter
Organic matter is moderate (3.1%). Annual compost additions will help Asparagus.
How to Plant Asparagus
Plant Water Budget
Monthly Watering Guide for Asparagus
Asparagus needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Asparagus Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3" | 0" | ❄️ Dormant |
| Feb | — | 3.2" | 0" | ❄️ Dormant |
| Mar | 3.5" | 4.3" | 0" | ✅ Rainfall sufficient |
| Apr | 3.5" | 4.8" | 0" | ✅ Rainfall sufficient |
| May | 3.5" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 5.4" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 4.4" | 0" | ✅ Rainfall sufficient |
| Sep | 3.5" | 4.1" | 0" | ✅ Rainfall sufficient |
| Oct | 3.5" | 3.9" | 0" | ✅ Rainfall sufficient |
| Nov | 3.5" | 3.7" | 0" | ✅ Rainfall sufficient |
| Dec | — | 4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Union County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Asparagus 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.
Asparagus Planting Timeline — Union County, NJ
Asparagus Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 12 | Apr 12 – Apr 26 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | — |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Natural rainfall sufficient
📅 Days to Maturity
730–1095 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 7a
📆 Growing Season
228 days in Union County
Growing Tips for Asparagus in Union County
Direct sow Asparagus outdoors after March 29 in Union County when soil has warmed and frost danger has passed.
Your 228.0-day growing season in Union County is tight for Asparagus (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
Plant crowns in deep trenches with compost. Do not harvest spears for the first two years to allow root establishment. Mulch heavily to suppress weeds and retain moisture.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Asparagus in Other Locations
Frequently Asked Questions
When should I plant Asparagus in Union County, NJ?
Union County is in Zone 7a with an average last frost of March 29. Plan your Asparagus planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, NJ?
Union County, New Jersey is in USDA Hardiness Zone 7a. The average last spring frost is March 29 and first fall frost is November 12.
Your Union County Garden Planner — Free
A 24-page printable planner built for Union County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.