When to Plant Tomatos in Longmont, CO

One of the first steps you take when you are determining 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.

One way of figuring out when it's the best time to plant tomatos is to consult the USDA zone info for Longmont.


Planting Calendar for Tomatos

Frost tolerance for tomatos: Not tolerant of frost.
When to plant: After the last frost when the weather gets warmer.

Since tomatos are not cold tolerant you need to wait until after the last frost has passed before you can plant them.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant tomatos
Possibly ok, but a risky time to plant tomatos
Probably not a good time to plant tomatos

The earliest that you can plant tomatos 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 tomatos and expect a good harvest is probably August. You probably don't want to wait any later than that or else your tomatos may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your tomatos indoors.

Last Frost Date

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

Remember 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. Since half of the time in Longmont there is a last frost after April 15 be ready to protect your tomatos if you have 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.