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When to Plant Nasturtium in Dallam County, TX

Dallam County, Texas Zone 6b June

Your June gardening checklist

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

Avg. last frost April 26
Avg. first frost October 14
Soil temp (4") 66°F
Watering High
Pest pressure High
Daylight 14.5 hrs
  1. Collect nasturtium at their peak

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

Before July arrives, get these ready
  • First harvests: nasturtium

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Nasturtium (Tropaeolum majus) is a fast-growing annual with distinctive round, lily-pad leaves and bold trumpet-shaped blooms in warm oranges, reds, and yellows. Both the flowers and leaves are edible with a peppery watercress flavor. Planted near vegetables, nasturtiums act as a sacrifice trap-crop, luring aphids away from more valuable plants. They thrive in poor, dry soil — rich conditions produce lush foliage but few flowers.

Dallam County, Texas is in USDA Zone 6b. The average last spring frost is April 26 and the first fall frost is October 14, giving you a growing season of approximately 171 days.

At an elevation of 3,388 feet, Dallam County receives approximately 54.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°F, so Nasturtium may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Nasturtium will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Nasturtium root diseases.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant Good for cutting Fragrant
Dallam County, TX (Zone 6b) Moderate season
171 days
Last Spring Frost April 26
171 growing days
First Fall Frost October 14

Dallam County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.9-8.4

Drainage

Well Drained

Nasturtium Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 23 Transplant: Apr 20 🌸 Bloom: Jun 15 – Oct 12
Recommended (50%) ✗ May not fit
Start indoors: Mar 29 Transplant: Apr 26 🌸 Bloom: Jun 21 – Oct 18
Safe Start (90%) ✗ May not fit
Start indoors: Apr 10 Transplant: May 8 🌸 Bloom: Jul 3 – Oct 30

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 Dallam County

How your county's soil matches Nasturtium's growing requirements.

Soil pH

Your soil pH (7.9–8.4) is more alkaline than Nasturtium prefers (6.0–8.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is low (1.1%). Add 2-3 inches of compost before planting Nasturtium.

How to Plant Nasturtium

0.5"
Planting Depth
10"
Between Plants
12"
Between Rows

Succession Planting Nasturtium

3
successive plantings in your 171-day season

Sow every 6.3 weeks. Last sowing by Aug 10 to harvest before frost.

Nasturtium Water Budget

Plant needs
0.5″/week
Rainfall provides
1.3″/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 Nasturtium

Nasturtium 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 Nasturtium Needs Rainfall You Supplement Action
Jan 4" 0" ❄️ Dormant
Feb 3" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.2" 1.7" 0.5" 💧 Light watering
May 2.2" 1" 1.2" 🚿 Regular watering
Jun 2.2" 1.7" 0.5" 💧 Light watering
Jul 2.2" 9.9" 0" ✅ Rainfall sufficient
Aug 2.2" 11.7" 0" ✅ Rainfall sufficient
Sep 2.2" 8" 0" ✅ Rainfall sufficient
Oct 2.2" 4" 0" ✅ Rainfall sufficient
Nov 3.3" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

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

Nasturtium 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.

Nasturtium needs ~1,320 GDD — county provides 3,762 GDD Excellent fit

Nasturtium Planting Timeline — Dallam County, TX

Nasturtium Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors April 26 Apr 26 – May 10
Direct Sow April 26 Apr 26 – May 17
Bloom June 21 Jun 21 – Oct 18

Plant 0.5" deep · 10" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Bloom
July Bloom
August Bloom
September Bloom
October Bloom
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

55–65 days

🧪 Soil pH

Needs 6–8 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

171 days in Dallam County

Growing Tips for Nasturtium in Dallam County

Direct sow Nasturtium outdoors after April 26 in Dallam County when soil has warmed and frost danger has passed.

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

With summer highs reaching 96°F in Dallam County, provide afternoon shade for Nasturtium and water deeply in the morning.

General growing tips

Direct-sow large seeds 1/2 inch deep after last frost; soak seeds overnight to speed germination (7-10 days). Nasturtiums dislike root disturbance so direct sowing is strongly preferred. Avoid fertilizing — poor soil brings the best bloom. Trailing types can cover banks and climb trellises; dwarf types suit containers. In hot climates (zones 9+) plant in fall for winter/spring bloom as plants struggle in peak summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Nasturtium in Dallam County, TX?

Dallam County is in Zone 6b with an average last frost of April 26. Plan your Nasturtium planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dallam County, TX?

Dallam County, Texas is in USDA Hardiness Zone 6b. The average last spring frost is April 26 and first fall frost is October 14.

🌱

Your Dallam County Garden Planner — Free

A 22-page printable planner built for Dallam 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 Dallam County, TX. Local conditions may vary. Last updated: June 2026.

Sources & credits

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