The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant geranium in Castle Rock can be determined by looking at the USDA zone info.

Planting Calendar for Geranium

Frost tolerance for geranium:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You can not plant geranium until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant geranium 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 geranium and expect a good harvest is probably August. Any later than that and your geranium may not have a chance to really do well. You can get started a few weeks earlier by starting your geranium indoors.

Last Frost Date

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

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Castle Rock and it is different every year. Half of the time in Castle Rock it frosts late in the year after April 15 so make sure that you are prepared to cover your geranium 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.