One of the first steps you take when you are figuring out your gardening schedule is find your 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 Thornton you can determine when it's a good idea to plant copperleaf by looking at the USDA zone info.

Planting Calendar for Copperleaf

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

You should not plant copperleaf until after the last frost has passed because they require warm weather.

The earliest that you can plant copperleaf in Thornton 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 copperleaf and expect a good harvest is probably August. If you wait any later than that and your copperleaf may not have a chance to really do well. You can get started a little bit earlier by starting your copperleaf indoors.

Last Frost Date

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

Since the USDA zone info for Thornton is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Thornton you get a frost after April 15 be ready to protect your copperleaf if you have one of those late frosts.

USDA Zone Info for Thornton

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 Thornton

You may be interested in your other planting guides for Thornton.