One of the first steps you take when you are making a decision about 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.

You should be able to estimate when you can plant larkspur by reviewing the USDA zone info for Longmont.

Planting Calendar for Larkspur

Frost tolerance for larkspur:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

You can plant larkspur quite a bit earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

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

Last Frost Date

On average the last frost has passed is on April 15 in Longmont. It might get as low as -15°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Longmont and it changes from year to year. Half of the time in Longmont there is a last frost after April 15 so make sure that you are prepared to protect your larkspur in the event of a late frost.

USDA Zone Info for Longmont

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Longmont

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