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.

It's possible to estimate when it's possible to plant sunflowers by referring to the USDA zone info for Boulder City.

Planting Calendar for Sunflowers

Frost tolerance for sunflowers:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Sunflowers do not do well in cold weather which means that it's important to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant sunflowers in Boulder City is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant sunflowers and expect a good harvest is probably September. Any later than that and your sunflowers may not have a chance to grow to maturity. Starting your sunflowers indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Boulder City the average date of last frost happens on February 15. In the coldest months of winter you should expect an average low temperature of 25°F.

Keep in mind that USDA zone info for Boulder City is not always accurate and the actual date of last frost changes from year to year. Half of the time in Boulder City there is a last frost after February 15 so make sure that you are ready to cover your sunflowers if you have a surprise late frost.

USDA Zone Info for Boulder City

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Boulder City

You may be interested in your other planting guides for Boulder City.