The USDA Zone info is a great tool for gardeners to help us figure out 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 Castle Rock should be read to figure out when it's possible to plant black radish.

Planting Calendar for Black radish

Frost tolerance for black radish:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Black radish do ok in some cold which means that you can plant them a little earlier in the year than other plants that might not handle the cold.

The earliest that you can plant black radish in Castle Rock 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 black radish and expect a good harvest is probably September. Any later than that and your black radish may not have a chance to grow to maturity. Starting your black radish indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Castle Rock. In the coldest months of winter you should expect an average low temperature of -15°F.

Keep in mind that USDA zone info for Castle Rock is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Castle Rock you get a frost after April 15 so just be sure to be ready to cover your black radish if you have a surprise late frost.

USDA Zone Info for Castle Rock

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Castle Rock

You may be interested in your other planting guides for Castle Rock.