One of the first steps you take when you are figuring out your gardening schedule is find your 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.

One way of making a decision about when it's possible to plant helianthemum is to use the USDA zone info for Baltimore.

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 means 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 Baltimore 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 really do well. You can get started a couple of weeks earlier by starting your helianthemum indoors.

Last Frost Date

The average date of last frost is April 15 in Baltimore. You should expect an average low temperature of 5°F in the coldest months of winter.

Remember 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 Baltimore and it can change quite a bit from year to year. Since half of the time in Baltimore there is a last frost after April 15 be ready to protect your helianthemum if you have one of those late frosts.

USDA Zone Info for Baltimore

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Baltimore

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