One of the first steps you take when you are getting a good idea 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.

By using the USDA zone info for Glasgow it's possible to estimate when it's the best time to plant penstemon.

Planting Calendar for Penstemon

Frost tolerance for penstemon:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Penstemon are moderately cold tolerant which means that you can start planting them earlier than more sensitive plants.

The earliest that you can plant penstemon in Glasgow is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant penstemon and expect a good harvest is probably September. If you wait any later than that and your penstemon may not have a chance to grow to maturity. If you are starting your penstemon indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Glasgow. In the coldest months of winter you can expect an average low temperature of -5°F.

It's important to remember that USDA zone info for Glasgow is not always accurate and the actual date of last frost is different every year. Since half of the time in Glasgow last frost occurs after April 15 be ready to cover your penstemon in the event of a late frost.

USDA Zone Info for Glasgow

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Glasgow

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