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 Thornton you can figure out when it's a good idea to plant nasturtium by looking at the USDA zone info.

Planting Calendar for Nasturtium

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

It's probably not a good idea to plant nasturtium until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant nasturtium 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 nasturtium and expect a good harvest is probably August. You probably don't want to wait any later than that or else your nasturtium may not have a chance to grow to maturity. If you are starting your nasturtium indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Thornton the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -15°F.

Remember that USDA zone info for Thornton is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Thornton you get a frost after April 15 be ready to protect your nasturtium in the event of a surprise late frost.

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.