The USDA Zone info is a great tool for gardeners to help us figure out 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 getting a good idea when it's the best time to plant helianthemum is to use the USDA zone info for Columbus.

Planting Calendar for Helianthemum

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

Helianthemum can survive in moderate cold which means that you can plant them a little bit earlier in the year than other frost tender plants.

The earliest that you can plant helianthemum in Columbus 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. If you wait any later than that and your helianthemum may not have a chance to fully mature. 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 Columbus. In the coldest months of winter you should expect an average low temperature of 15°F.

Always keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Columbus and it is different every year. Since half of the time in Columbus you get surprised by a frost after March 15 be ready to cover your helianthemum in the event of a surprise late frost.

USDA Zone Info for Columbus

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Columbus

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