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.

In Castle Rock you can determine when to plant tropical hibiscus by using the USDA zone info.

Planting Calendar for Tropical Hibiscus

Frost tolerance for tropical hibiscus:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since tropical hibiscus are not cold tolerant it's important to wait until after the last frost before you can plant them.

The earliest that you can plant tropical hibiscus 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 tropical hibiscus and expect a good harvest is probably August. Any later than that and your tropical hibiscus may not have a chance to fully mature. You can get started a little bit earlier by starting your tropical hibiscus indoors.

Last Frost Date

In Castle Rock the average date of last frost happens on April 15. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Castle Rock is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Castle Rock it frosts late in the year after April 15 be ready to protect your tropical hibiscus 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.