One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to estimate when it's a good idea to plant spinach by looking at the USDA zone info for Castle Rock.

Planting Calendar for Spinach

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

Spinach are one of those plants that can tolerate a little bit of cold weather which means that you can plant them earlier than other plants that might not handle the cold.

The earliest that you can plant spinach 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 spinach and expect a good harvest is probably September. If you wait any later than that and your spinach may not have a chance to fully mature. If you are starting your spinach indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Castle Rock. In the coldest months of winter you should expect an average low temperature of -15°F.

Since the USDA zone info for Castle Rock may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Castle Rock there is a last frost after April 15 so just be sure to be ready to protect your spinach in the event of 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.