One of the best tools that you have as gardeners to help us figure out 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.

The USDA zone info for Tempe should be looked at to determine when to plant helianthemum.

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 plant them a little bit earlier than other plants that might not handle the cold.

The earliest that you can plant helianthemum in Tempe is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant helianthemum and expect a good harvest is probably October. If you wait any later than that and your helianthemum may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your helianthemum indoors.

Last Frost Date

On average all chance of frost has passed is on February 15 in Tempe. You should expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Tempe is just an average the actual date of last frost is different every year. Half of the time in Tempe last frost occurs after February 15 so make sure that you are ready to protect your helianthemum if you have one of those late frosts.

USDA Zone Info for Tempe

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 Tempe

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