Before planting it is a good idea to find your USDA Zone info to figure out 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 earliest that you can plant regal geranium in Waltham should be determined by reviewing the USDA zone info.

Planting Calendar for Regal Geranium

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

Regal Geranium can survive in very little cold which tells us that you can plant them slightly earlier in the year than other frost tender plants.

The earliest that you can plant regal geranium in Waltham is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant regal geranium and expect a good harvest is probably August. You probably don't want to wait any later than that or else your regal geranium may not have a chance to really do well. If you are starting your regal geranium indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Waltham the average date of last frost happens on April 15. You can expect an average low temperature of -10°F in the coldest months of winter.

Keep in mind that USDA zone info for Waltham is not always accurate and the actual date of last frost is different every year. Half of the time in Waltham there is a last frost after April 15 so just be sure to be ready to protect your regal geranium if you have a 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.