Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Waltham you can estimate when it's a good idea to plant salpiglossis by using the USDA zone info.

Planting Calendar for Salpiglossis

Frost tolerance for salpiglossis:	Not tolerant of frost.
When to plant:	After the last frost.

It's probably not a good idea to plant salpiglossis until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant salpiglossis 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 salpiglossis and expect a good harvest is probably August. Any later than that and your salpiglossis may not have a chance to grow to maturity. If you are starting your salpiglossis 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 April 15 in Waltham. In the coldest months of winter you should expect an average low temperature of -10°F.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Waltham and it can change quite a bit from year to year. Half of the time in Waltham last frost occurs after April 15 so always be ready to protect your salpiglossis 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.