The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Helena can be read to determine when you can plant radishes.

Planting Calendar for Radishes

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

You can plant radishes quite a bit earlier in the year because they are very cold tolerant.

The earliest that you can plant radishes in Helena 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. If you wait any later than that and your radishes may not have a chance to fully mature. If you are starting your radishes indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Helena the average date of last frost happens on March 15. It might get as low as 10°F during the coldest months of winter.

It's important to remember that USDA zone info for Helena is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Helena you get surprised by a frost after March 15 so just be sure to be ready to cover your radishes if you have a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Helena

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