Gardening Frost Date Calculator

Calculate first and last frost dates for your location and determine optimal planting windows for different crops. This calculator helps gardeners plan their growing season and maximize crop success.

How to Use This Calculator

Enter your location’s hardiness zone
Input average first and last frost dates
Select crops you plan to grow
The calculator will provide:
- Safe planting dates
- Growing season length
- Harvest windows
- Indoor start dates

Understanding Frost Dates

First Frost Date

The first frost date is when temperatures first drop to 32°F (0°C) in fall, marking the end of the growing season for tender plants.

Last Frost Date

The last frost date is when temperatures rise above 32°F (0°C) in spring, indicating when it’s safe to plant tender crops outdoors.

Frost-Free Days

The number of days between the last spring frost and first fall frost determines your growing season length.

USDA Hardiness Zones

Zone Characteristics

Zone 3: -40°F to -30°F
Zone 4: -30°F to -20°F
Zone 5: -20°F to -10°F
Zone 6: -10°F to 0°F
Zone 7: 0°F to 10°F
Zone 8: 10°F to 20°F
Zone 9: 20°F to 30°F
Zone 10: 30°F to 40°F

Planting Guidelines

Cold-Hardy Vegetables

Plant 4-6 weeks before last frost
Examples: peas, spinach, lettuce
Can survive light frosts
Extended harvest season

Semi-Hardy Vegetables

Plant 2-3 weeks before last frost
Examples: carrots, beets, potatoes
Tolerate light frost
Need protection in cold snaps

Tender Vegetables

Plant after last frost
Examples: tomatoes, peppers, beans
No frost tolerance
Need warm soil temperatures

Heat-Loving Vegetables

Plant 2-3 weeks after last frost
Examples: melons, squash, corn
Need consistently warm temperatures
Long growing season

Starting Seeds Indoors

Timing Guidelines

Long-Season Crops
- Start 10-12 weeks before last frost
- Tomatoes, peppers, eggplants
- Need significant indoor growing time
Medium-Season Crops
- Start 6-8 weeks before last frost
- Broccoli, cabbage, cauliflower
- Moderate indoor growing time
Short-Season Crops
- Start 4-6 weeks before last frost
- Lettuce, herbs, cucumbers
- Brief indoor growing period

Season Extension Methods

Cold Frames

Extend season by 4-8 weeks
Protection from frost
Earlier spring planting
Later fall harvest

Row Covers

Light frost protection
Temperature increase 2-4°F
Pest protection
Wind shelter

Greenhouses

Year-round growing possible
Complete climate control
Protection from all weather
Extended growing season

Crop-Specific Guidelines

Spring Crops

March Planting
- Peas
- Spinach
- Radishes
- Lettuce
April Planting
- Carrots
- Beets
- Potatoes
- Onions
May Planting
- Tomatoes
- Peppers
- Beans
- Cucumbers

Fall Crops

July Planting
- Carrots
- Beets
- Turnips
- Fall peas
August Planting
- Lettuce
- Spinach
- Radishes
- Asian greens
September Planting
- Garlic
- Cover crops
- Cold-hardy greens

Frequently Asked Questions

What is a killing frost?

A killing frost occurs when temperatures drop below 28°F (-2°C), causing severe damage to most plants. This typically marks the definitive end of the growing season.

How do microclimates affect frost dates?

Local conditions like buildings, slopes, and water bodies can create microclimates that affect frost patterns. Urban areas often have later first frosts and earlier last frosts than surrounding rural areas.

Should I rely solely on frost dates?

While frost dates are important guidelines, also consider:

Soil temperature
Precipitation patterns
Local weather trends
Specific crop requirements

How can I protect plants from unexpected frost?

Emergency frost protection methods:

Cover plants with blankets/row covers
Water before frost (creates protective barrier)
Use cold frames or cloches
Move container plants indoors

Tips for Success

Record Keeping
- Document frost dates
- Track planting times
- Note successful varieties
- Monitor weather patterns
Soil Preparation
- Test soil temperature
- Ensure good drainage
- Add organic matter
- Maintain proper pH
Weather Monitoring
- Watch forecasts closely
- Have protection ready
- Know critical temperatures
- Monitor local conditions