The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of making a decision about when to plant helianthemum is to consult the USDA zone info for Sunnyvale.

Planting Calendar for Helianthemum

Frost tolerance for helianthemum:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Helianthemum do well in moderate cold which tells us that you can get them planted earlier than other plants that might not handle the cold.

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

Last Frost Date

On average all chance of frost has passed is on March 15 in Sunnyvale. In the coldest months of winter you should expect an average low temperature of 10°F.

Since the USDA zone info for Sunnyvale is not always accurate the actual date of last frost will vary from year to year. Half of the time in Sunnyvale you get a frost after March 15 so make sure that you are prepared to cover your helianthemum if you have a late frost.

USDA Zone Info for Sunnyvale

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Sunnyvale

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