The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You will be able to estimate when you can plant astilbe by using the USDA zone info for Sunnyvale.

Planting Calendar for Astilbe

Frost tolerance for astilbe:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Astilbe are one of those plants that can tolerate a tiny bit of cold weather which tells us that you can plant them slightly earlier than plants that are more sensitive to the cold.

The earliest that you can plant astilbe in Sunnyvale 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 astilbe and expect a good harvest is probably September. Any later than that and your astilbe may not have a chance to fully mature. If you are starting your astilbe indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is February 15 in Sunnyvale. It might get as low as 25°F during the coldest months of winter.

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Sunnyvale and it can change quite a bit from year to year. Since half of the time in Sunnyvale it frosts late in the year after February 15 be ready to cover your astilbe if you have a late frost.

USDA Zone Info for Sunnyvale

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 Sunnyvale

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