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When to Plant Asparagus in Union County, NM

Union County, New Mexico Zone 6b May

May in the garden — Union County, New Mexico

Here's what deserves your attention in Union County, New Mexico this month. Everything below is tailored to Zone 6b and timed around your local frost dates.

Avg. last frost April 30
Avg. first frost October 9
Soil temp (4") 42°F
Watering Critical
Pest pressure Low
Daylight 13.9 hrs
  1. Move asparagus from tray to bed

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

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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 Mexico is in USDA Zone 6b. The average last spring frost is April 30 and the first fall frost is October 9, giving you a growing season of approximately 162 days.

At an elevation of 6,384 feet, Union County receives approximately 17.5 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 85°F, providing good warmth for Asparagus during the growing season. Sandy soil warms quickly in spring — great for early planting — but Asparagus will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Asparagus successfully. Mulch heavily to conserve soil moisture.

Union County, NM (Zone 6b) Moderate season
162 days
Last Spring Frost April 30
162 growing days
First Fall Frost October 9
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Union County Soil Profile

Soil Type

Sandy Loam

Soil pH

6.9-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: May 9
Recommended (50%) ✓ Fits season
Transplant: May 14
Safe Start (90%) ✓ Fits season
Transplant: May 31

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 (6.9–8.3) is more alkaline than Asparagus prefers (6.5–7.5). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Union County warms quickly in spring but drains fast. Asparagus will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Asparagus.

Organic Matter

Organic matter is low (0.9%). Add 2-3 inches of compost before planting Asparagus.

How to Plant Asparagus

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.5″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 1,014 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — consider drought-tolerant varieties and mulching

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 1.1" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 3.5" 0.6" 2.9" 🚿 Regular watering
May 3.5" 0.4" 3.1" 🚿 Regular watering
Jun 3.5" 0.6" 2.9" 🚿 Regular watering
Jul 3.5" 3" 0.5" 💧 Light watering
Aug 3.5" 4" 0" ✅ Rainfall sufficient
Sep 3.5" 2.1" 1.4" 💧 Light watering
Oct 3.5" 1.4" 2.1" 🚿 Regular watering
Nov 1" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct 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 needs ~12,547 GDD — county provides 2,227 GDD May not mature

Asparagus Planting Timeline — Union County, NM

Asparagus Planting Calendar

Activity When Date Range
Transplant Outdoors May 14 May 14 – May 28

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June
July
August
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · 2-3 times/week

📅 Days to Maturity

730–1095 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

162 days in Union County

Growing Tips for Asparagus in Union County

Direct sow Asparagus outdoors after April 30 in Union County when soil has warmed and frost danger has passed.

Sandy soil in Union County dries quickly — mulch Asparagus with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Your 162.0-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

  • Garlic
  • Onion

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Asparagus in Union County, NM?

Union County is in Zone 6b with an average last frost of April 30. Plan your Asparagus planting based on this frost date — see the calendar above for exact timing.

What planting zone is Union County, NM?

Union County, New Mexico is in USDA Hardiness Zone 6b. The average last spring frost is April 30 and first fall frost is October 9.

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Your Union County Garden Planner — Free

A 24-page printable planner built for Union County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Union County, NM. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.