Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By using the USDA zone info for Thornton it's a good idea to determine when you can plant twinspur.

Planting Calendar for Twinspur

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

Twinspur do ok in a little bit of cold which means that you can plant them just a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant twinspur in Thornton 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 twinspur and expect a good harvest is probably September. If you wait any later than that and your twinspur may not have a chance to really do well. Starting your twinspur indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Thornton. You should expect an average low temperature of -15°F in the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Thornton and it changes from year to year. Since half of the time in Thornton you get a frost after April 15 be ready to protect your twinspur 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.