One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to figure out when you can plant cleome by referring to the USDA zone info for Waltham.

Planting Calendar for Cleome

Frost tolerance for cleome:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Cleome are not cold tolerant which means that you have to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant cleome in Waltham 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 cleome and expect a good harvest is probably August. If you wait any later than that and your cleome may not have a chance to fully mature. You can get started a few weeks earlier by starting your cleome indoors.

Last Frost Date

In Waltham the average date of last frost happens on April 15. It might get as low as -10°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Waltham may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Waltham you get a frost after April 15 so make sure that you are ready to cover your cleome in the event of a surprise late frost.

USDA Zone Info for Waltham

Here is the info for USDA Zone 6a.

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

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

Plants to Grow in Waltham

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