Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to estimate when it's a good idea to plant radishes by reviewing the USDA zone info for Waterloo.

Planting Calendar for Radishes

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

Since radishes are one of those plants that can tolerate quite a bit of cold weather you can plant them earlier in the year than other frost tender plants.

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

The last month that you can plant radishes and expect a good harvest is probably September. Any later than that and your radishes may not have a chance to fully mature. Starting your radishes indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Waterloo. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Waterloo is not always accurate the actual date of last frost is different every year. Half of the time in Waterloo you get a frost after April 15 so just be sure to be ready to cover your radishes in the event of a late frost.

USDA Zone Info for Waterloo

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Waterloo

You may be interested in your other planting guides for Waterloo.