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When to Plant Cress in Mercer County, NJ

Mercer County, New Jersey Zone 7a May

May in the garden — Mercer County, New Jersey

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

Avg. last frost April 12
Avg. first frost October 29
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 14.2 hrs
  1. Start cress indoors

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

  2. Basket week: cress

    If you can't use it all right away, check the food-preservation section of your planner.

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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.

Mercer County, New Jersey is in USDA Zone 7a. The average last spring frost is April 12 and the first fall frost is October 29, giving you a growing season of approximately 200 days.

At an elevation of 4 feet, Mercer County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Cress during the growing season.

Mercer County, NJ (Zone 7a) Long season
200 days
Last Spring Frost April 12
200 growing days
First Fall Frost October 29
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Mercer County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (161 days to spare)
Start indoors: Mar 1 Transplant: Apr 5 🍅 Harvest: Apr 19 – May 10
Recommended (50%) ✓ Fits season (165 days to spare)
Start indoors: Mar 8 Transplant: Apr 12 🍅 Harvest: Apr 26 – May 17
Safe Start (90%) ✓ Fits season (160 days to spare)
Start indoors: Mar 27 Transplant: May 1 🍅 Harvest: May 15 – Jun 5

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 Mercer County

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

Soil pH

Your soil pH (5.0–6.7) is more acidic than Cress prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (4.0%). 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

17
successive plantings in your 200-day season

Sow every 1.6 weeks. Last sowing by Oct 08 to harvest before frost.

For a dedicated fall crop, sow by Aug 20.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 79 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 3.1" 0" ❄️ Dormant
Feb 3.3" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 4.3" 4.1" 0.2" 💧 Light watering
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 4.8" 0" ✅ Rainfall sufficient
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 3.8" 0.5" 💧 Light watering
Nov 3.8" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Mercer 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 ~306 GDD — county provides 3,500 GDD Excellent fit

Cress Planting Timeline — Mercer County, NJ

Cress Planting Calendar

Activity When Date Range
Start Indoors March 8 Mar 8 – Mar 22
Transplant Outdoors April 12 Apr 12 – Apr 26
Direct Sow March 29 Mar 29 – Apr 19
Harvest April 26 Apr 26 – May 17
Fall Sowing August 20 Aug 20 – Sep 3

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 · Only during dry spells

📅 Days to Maturity

14–21 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

200 days in Mercer County

Growing Tips for Cress in Mercer County

Direct sow Cress outdoors after April 12 in Mercer County when soil has warmed and frost danger has passed.

Your generous 200.0-day season in Mercer 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 Mercer County, NJ?

Mercer County is in Zone 7a with an average last frost of April 12. Plan your Cress planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mercer County, NJ?

Mercer County, New Jersey is in USDA Hardiness Zone 7a. The average last spring frost is April 12 and first fall frost is October 29.

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Your Mercer County Garden Planner — Free

A 24-page printable planner built for Mercer 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.

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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 Mercer County, NJ. 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.