Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to determine when to plant helianthemum by referring to the USDA zone info for Gretna.

Planting Calendar for Helianthemum

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

Since helianthemum are moderately cold tolerant you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant helianthemum in Gretna 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. Any later than that and your helianthemum may not have a chance to really do well. Starting your helianthemum indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Gretna the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Gretna is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Gretna it frosts late in the year after April 15 so be sure to be ready to cover your helianthemum in the event of one of those late frosts.

USDA Zone Info for Gretna

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

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

Plants to Grow in Gretna

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