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

A way of estimating when it's a good idea to plant dahlias is to examine the USDA zone info for Cupertino.

Planting Calendar for Dahlias

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

Since dahlias require warm weather you have to wait until after the last frost has passed before you can plant them.

The earliest that you can plant dahlias in Cupertino 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 dahlias and expect a good harvest is probably September. You probably don't want to wait any later than that or else your dahlias may not have a chance to fully mature. Starting your dahlias indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Cupertino the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Cupertino may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Cupertino there is a last frost after February 15 so make sure that you are ready to cover your dahlias if you have a late frost.

USDA Zone Info for Cupertino

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 Cupertino

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