One of the best tools that you have as gardeners to help us figure out 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.

In Watertown you can determine when it's possible to plant bougainvillea by reviewing the USDA zone info.

Planting Calendar for Bougainvillea

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

Since bougainvillea are not cold tolerant you need to wait until after all chance of frost has passed before you can plant them.

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

The last month that you can plant bougainvillea and expect a good harvest is probably August. If you wait any later than that and your bougainvillea may not have a chance to really do well. Starting your bougainvillea indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Watertown the average date of last frost happens on May 15. You should expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Watertown may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Watertown it frosts late in the year after May 15 be ready to protect your bougainvillea in the event of one of those late frosts.

USDA Zone Info for Watertown

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 Watertown

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