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When to Plant Cress in Union County, SC

Union County, South Carolina Zone 8a May

Union County, South Carolina gardeners: here's your May plan

Your Union County, South Carolina garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost April 5
Avg. first frost October 31
Soil temp (4") 67°F
Watering Low
Pest pressure Moderate
Daylight 13.8 hrs
  1. Get cress seeds going inside

    Your window is short. These crops want several weeks of indoor growth before they go outside.

  2. Basket week: cress

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

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Garden cress is one of the fastest-growing edibles, producing peppery sprouts in as little as two weeks. It is excellent for microgreens and garnishes.

Union County, South Carolina is in USDA Zone 8a. The average last spring frost is April 5 and the first fall frost is October 31, giving you a growing season of approximately 209 days.

At an elevation of 478 feet, Union County receives approximately 53.3 inches of rainfall annually with predominantly clay loam soil. Summer highs average 91°F, providing good warmth for Cress during the growing season. Clay soil retains moisture well for Cress, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cress root diseases.

Union County, SC (Zone 8a) Long season
209 days
Last Spring Frost April 5
209 growing days
First Fall Frost October 31
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Union County Soil Profile

Soil Type

Clay Loam

Soil pH

5.7-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (177 days to spare)
Start indoors: Feb 20 Transplant: Mar 27 🍅 Harvest: Apr 10 – May 1
Recommended (50%) ✓ Fits season (174 days to spare)
Start indoors: Mar 1 Transplant: Apr 5 🍅 Harvest: Apr 19 – May 10
Safe Start (90%) ✓ Fits season (182 days to spare)
Start indoors: Mar 14 Transplant: Apr 18 🍅 Harvest: May 2 – May 23

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 Cress's growing requirements.

Soil pH

Your soil pH (5.7–6.3) overlaps with Cress's range (6.0–7.0), though not a perfect match.

Soil Texture

The clay loam soil in Union County is excellent for Cress — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Cress.

How to Plant Cress

0.5"
Planting Depth
2"
Between Plants
6"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Cress

18
successive plantings in your 209-day season

Sow every 1.6 weeks. Last sowing by Oct 10 to harvest before frost.

For a dedicated fall crop, sow by Aug 22.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Cress

Cress needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Cress Needs Rainfall You Supplement Action
Jan 5.1" 0" ❄️ Dormant
Feb 3.9" 0" ❄️ Dormant
Mar 4.5" 0" ❄️ Dormant
Apr 4.3" 4.5" 0" ✅ Rainfall sufficient
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 5.2" 0" ✅ Rainfall sufficient
Jul 4.3" 5.5" 0" ✅ Rainfall sufficient
Aug 4.3" 4.5" 0" ✅ Rainfall sufficient
Sep 4.3" 4" 0.3" 💧 Light watering
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 4.1" 0" ❄️ Dormant
Dec 4.8" 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.

Cress 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.

Cress needs ~319 GDD — county provides 3,814 GDD Excellent fit

Cress Planting Timeline — Union County, SC

Cress 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 April 19 Apr 19 – May 10
Fall Sowing August 22 Aug 22 – Sep 5

Plant 0.5" deep · 2" apart · Rows 6" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors Direct Sow
April Transplant Outdoors Direct Sow Harvest
May Harvest
June
July
August Fall Sowing
September Fall Sowing
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

14–21 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 8a

📆 Growing Season

209 days in Union County

Growing Tips for Cress in Union County

Direct sow Cress outdoors after April 05 in Union County when soil has warmed and frost danger has passed.

With Union County's clay soil (27% clay), work in 3-4 inches of compost before planting Cress. Avoid tilling when soil is wet to prevent compaction.

Your generous 209.0-day season in Union County allows multiple plantings of Cress. Sow every 7.0 days for continuous harvest.

Common pests for Cress in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds thickly on moist soil or paper towels. Keep moist and harvest when 2-3 inches tall. Succession sow every few days for continuous supply. Grows well indoors year-round.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cress in Union County, SC?

Union County is in Zone 8a with an average last frost of April 5. Plan your Cress planting based on this frost date — see the calendar above for exact timing.

What planting zone is Union County, SC?

Union County, South Carolina is in USDA Hardiness Zone 8a. The average last spring frost is April 5 and first fall frost is October 31.

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Your Union County Garden Planner — Free

A 24-page printable planner built for Union 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.

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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, SC. 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.