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When to Plant Tall Phlox in Rock Springs, WY

The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. 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 estimate when it's possible to plant tall phlox by using the USDA zone info for Rock Springs.

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Planting Calendar for Tall Phlox

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

Tall Phlox are moderately cold tolerant which means that you can get them planted earlier than plants that are more sensitive to the cold.

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

The earliest that you can plant tall phlox in Rock Springs 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 tall phlox and expect a good harvest is probably September. If you wait any later than that and your tall phlox may not have a chance to fully mature. If you are starting your tall phlox 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 Rock Springs. It might get as low as -20°F during the coldest months of winter.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Rock Springs and it can change quite a bit from year to year. Half of the time in Rock Springs it frosts late in the year after April 15 so just be sure to be ready to protect your tall phlox in the event of one of those late frosts.

USDA Zone Info for Rock Springs

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low-20°F
Highest Expected Low-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Rock Springs

You may be interested in your other planting guides for Rock Springs.