Best Soil Temperatures for Sowing Vegetable Seeds

Did you know if you sow seeds at certain soil temperatures you will get the best germination rates? Every plant species has its own sweet spot, and the more we accommodate this, the better the results. Start measuring your soil temperature to know the best time to sow seeds.

For more beginner tips, also see Seed Starting 101 and clever ways gardeners use warmth to speed up seed germination. This lists best soil temperatures for flowers and herbs.

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Using Soil Temperatures For Better Germination

This is one of the best kept secrets in gardening. Each type of seed has a sweet spot—a preferred soil temperature—where germination is most successful. If conditions including temperature are right, you get maximum germination rates and faster growth.

When growing vegetables, the closer we are to best soil temperatures for germination, the more plants we will have.

I’ve provided a chart listing the best soil temperature for each vegetable, suggestions to simplify your sowing, and growing tips including how to measure soil temperature.

There is also a printable chart in the Resources section.

Contents

• Vegetable Seed Sowing Soil Temperature Chart
• Simple Sowing Options
• Why Soil Temperature Matters
• How to Measure Soil Temperature
• Frequently Asked Questions
• Resources

Why Temperature Matters

Seed Storage

To store seeds and prevent germination, it is recommended to keep them in a cool, dry, dark place with consistent temperatures between 32-41°F (0-5°C) and not more than 50% relative humidity levels.

• Best Ways to Store Seeds at Home (Fridge & Other Options)
• How Seeds Are Kept in Long-Term Storage (Global Seed Vault)

Seed Germination

To awaken seeds from dormancy and trigger germination, conditions must change. When we sow a seed, we introduce water (moisture), which softens the protective coat, and warmer temperatures which provoke growth. Air and light play a role as well.

When we look at temperatures for seed germination, it is the temperature of the soil or growing medium in direct contact with the seed or roots that is so important. Research shows that every single plant species has its own preferences. Getting the soil temperature right—or within optimum range—can greatly affect germination rates.

Example

• Ten pepper seeds started at 60°F (15°C) may yield one or two plants, and take weeks to sprout.
• The same number of seeds started at 85°F (29°C) may sprout within days and yield 8-10 happy plants.
• But, beyond that temperature, the seeds may not survive.

This is what we refer to as a seed liking “warm feet.” Keep in mind that this is just one example and the sweet spot is different for each plant species (and can vary by subspecies as well).

How to Measure Soil Temperature

• For a good temperature reading, place the thermometer in the soil approximately 3″ deep (or however deep the tip allows) and allow a minute for a definite reading.
• Measure both in the morning and afternoon, a few days in a row.
• The process is the same for indoor seed starting. Take enough readings that you are confident the soil is consistently within the desired temperature range.
• Note all the readings and take the average. When the average is in range, it’s sowing time—assuming it’s the right time of year.

Thermometers

You can use a kitchen meat thermometer to measure soil temperature or get an official soil thermometer, which is really the same thing. I have a digital thermometer with a metal probe and it works nicely.

Frequently Asked Questions

Resources

Free Printable

If you would like to save the soil temperature chart, click on button (below).

New to saving files? There are step-by-step instructions here.

~Melissa the Empress of Dirt ♛