Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to estimate when it's a good idea to plant sunflowers by using the USDA zone info for Colusa.

Planting Calendar for Sunflowers

Frost tolerance for sunflowers:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You really shouldn't plant sunflowers until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant sunflowers in Colusa 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. You probably don't want to wait any later than that or else your sunflowers may not have a chance to fully mature. If you are starting your sunflowers indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Colusa the average date of last frost happens on February 15. You should expect an average low temperature of 25°F in the coldest months of winter.

Keep in mind that USDA zone info for Colusa is an average and the actual date of last frost will vary from year to year. Half of the time in Colusa it frosts late in the year after February 15 so be sure to be ready to protect your sunflowers if you have a surprise late frost.

USDA Zone Info for Colusa

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 Colusa

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