One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of making a decision about when to plant cosmos is to examine the USDA zone info for Cambridge.

Planting Calendar for Cosmos

Frost tolerance for cosmos:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since cosmos are one of those plants that can tolerate a tiny bit of cold weather you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant cosmos in Cambridge is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant cosmos and expect a good harvest is probably August. Any later than that and your cosmos may not have a chance to fully mature. If you are starting your cosmos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost is on May 15 in Cambridge. You should expect an average low temperature of -30°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Cambridge is not always accurate and the actual date of last frost is different every year. Half of the time in Cambridge you get surprised by a frost after May 15 so make sure that you are prepared to cover your cosmos in the event of a surprise late frost.

USDA Zone Info for Cambridge

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Cambridge

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