One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of estimating when it's the best time to plant helianthemum is to refer to the USDA zone info for Rockwall.

Planting Calendar for Helianthemum

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

Helianthemum are one of those plants that can tolerate a little bit of cold weather which tells us that you can start planting them earlier than other plants that might not handle the cold.

The earliest that you can plant helianthemum in Rockwall 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. Starting your helianthemum indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Rockwall the average date of last frost happens on March 15. It might get as low as 10°F during the coldest months of winter.

Keep in mind that USDA zone info for Rockwall may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Rockwall it frosts late in the year after March 15 be ready to cover your helianthemum if you have one of those late frosts.

USDA Zone Info for Rockwall

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 Rockwall

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