When to Plant Lobelia in Thornton, CO

Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant lobelia in Thornton should be determined by looking at the USDA zone info.

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Planting Calendar for Lobelia

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

You can plant lobelia quite a bit earlier in the year because they do well in cold.

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

The earliest that you can plant lobelia in Thornton 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 lobelia and expect a good harvest is probably September. You probably don't want to wait any later than that or else your lobelia may not have a chance to grow to maturity. You can get started a little bit earlier by starting your lobelia indoors.

Last Frost Date

The average date of last frost is April 15 in Thornton. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Thornton may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Thornton last frost occurs after April 15 be ready to protect your lobelia if you have a late frost.

USDA Zone Info for Thornton

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 Thornton

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