One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when you can plant radishes in Zone 4b by reviewing the USDA zone info.

Planting Calendar for Radishes

Frost tolerance for radishes:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Radishes are one of those plants that can tolerate quite a bit of cold weather which tells us that you can start planting them much earlier than other plants that might not handle the cold.

The earliest that you can plant radishes in Zone 4b is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant radishes and expect a good harvest is probably August. Any later than that and your radishes may not have a chance to really do well. You can get started a few weeks earlier by starting your radishes indoors.

Last Frost Date

In Zone 4b the average date of last frost happens on May 15. You should expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Zone 4b is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Zone 4b it frosts late in the year after May 15 be ready to cover your radishes if you have one of those late frosts.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.