One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to determine when it's the best time to plant bidens by referring to the USDA zone info for Longmont.

Planting Calendar for Bidens

Frost tolerance for bidens:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since bidens do not do well in cold weather you really should wait until after the last frost has passed before you can plant them.

The earliest that you can plant bidens in Longmont 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 bidens and expect a good harvest is probably August. Any later than that and your bidens may not have a chance to grow to maturity. If you are starting your bidens indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Longmont is just an average the actual date of last frost changes from year to year. Since half of the time in Longmont there is a last frost after April 15 be ready to cover your bidens if you have one of those late frosts.

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.