One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. 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 can be used to figure out when it's a good idea to plant four o' clock.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You should not plant four o' clock until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant four o' clock in Castle Rock is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant four o' clock and expect a good harvest is probably August. If you wait any later than that and your four o' clock may not have a chance to fully mature. Starting your four o' clock indoors is a great way to get them started a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Castle Rock is an average the actual date of last frost is different every year. Since half of the time in Castle Rock you get a frost after April 15 be ready to cover your four o' clock if you have a 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.