Before planting it is a good idea to find your USDA Zone info to estimate 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.

The USDA zone info for Cambridge should be reffered to in order to estimate when it's the best time 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 are moderately cold tolerant which tells us that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant helianthemum in Cambridge 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 grow to maturity. You can get started a few weeks earlier by starting your helianthemum indoors.

Last Frost Date

In Cambridge the average date of last frost happens on April 15. It might get as low as -5°F during the coldest months of winter.

Since the USDA zone info for Cambridge may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Cambridge last frost occurs after April 15 so just be sure to be ready to cover your helianthemum if you have a late frost.

USDA Zone Info for Cambridge

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°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 0°F.

Plants to Grow in Cambridge

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