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When to Plant Garlic Chives in Costilla County, CO

Costilla County, Colorado Zone 5b May

May to-do list for Costilla County, Colorado

Your garden in Costilla County, Colorado is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost June 8
Avg. first frost September 16
Soil temp (4") 43°F
Watering High
Pest pressure Low
Daylight 14 hrs
June will be here before you know it — start on
  • Transplants going out: garlic chives

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Garlic chives are a perennial herb with flat leaves that have a mild garlic flavor. They produce attractive white flower clusters and are used in Asian cooking.

Costilla County, Colorado is in USDA Zone 5b. The average last spring frost is June 8 and the first fall frost is September 16, giving you a growing season of approximately 100 days.

At an elevation of 5,598 feet, Costilla County receives approximately 21 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Garlic Chives during the growing season.

Costilla County, CO (Zone 5b) Short season
100 days
Last Spring Frost June 8
100 growing days
First Fall Frost September 16
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Costilla County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Jun 6 🍅 Harvest: Aug 8 – Oct 17
Recommended (50%) ✗ May not fit
Transplant: Jun 15 🍅 Harvest: Aug 17 – Oct 26
Safe Start (90%) ✗ May not fit
Transplant: Jun 26 🍅 Harvest: Aug 28 – Nov 6

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 Costilla County

How your county's soil matches Garlic Chives's growing requirements.

Soil pH

Your soil pH (6.2–8.3) overlaps with Garlic Chives's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Costilla County is excellent for Garlic Chives — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Garlic Chives.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Garlic Chives.

How to Plant Garlic Chives

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Garlic Chives

Garlic Chives needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Garlic Chives Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 2.5" 0" ❄️ Dormant
Jun 2.2" 1.3" 0.9" 💧 Light watering
Jul 2.2" 2" 0.2" 💧 Light watering
Aug 2.2" 2.5" 0" ✅ Rainfall sufficient
Sep 2.2" 1.7" 0.5" 💧 Light watering
Oct 1.9" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Costilla County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Garlic Chives 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.

Garlic Chives needs ~1,088 GDD — county provides 1,450 GDD Excellent fit

Garlic Chives Planting Timeline — Costilla County, CO

Garlic Chives Planting Calendar

Activity When Date Range
Transplant Outdoors June 15 Jun 15 – Jun 29
Harvest August 17 Aug 17 – Oct 26

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

100 days in Costilla County

Growing Tips for Garlic Chives in Costilla County

Direct sow Garlic Chives outdoors after June 08 in Costilla County when soil has warmed and frost danger has passed.

Your 100.0-day growing season in Costilla County is tight for Garlic Chives (60.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Garlic Chives in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

Costilla County receives only 21" of rain annually. Garlic Chives needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start from seed or divisions. Cut flower stalks before seeds set to prevent aggressive self-seeding. Both leaves and flower buds are edible and flavorful.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Garlic Chives in Costilla County, CO?

Costilla County is in Zone 5b with an average last frost of June 8. Plan your Garlic Chives planting based on this frost date — see the calendar above for exact timing.

What planting zone is Costilla County, CO?

Costilla County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 8 and first fall frost is September 16.

🌱

Your Costilla County Garden Planner — Free

A 24-page printable planner built for Costilla County (Zone 5b). 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 Costilla County, CO. 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.