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

In Marengo you can estimate when it's the best time to plant tall phlox by looking at the USDA zone info.

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 tend to make it in some cold which means that you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant tall phlox in Marengo 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. Any later than that and your tall phlox may not have a chance to really do well. If you are starting your tall phlox indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Marengo. In the coldest months of winter you can expect an average low temperature of -15°F.

Remember that USDA zone info for Marengo is an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Marengo it frosts late in the year after April 15 so be sure to be ready to cover your tall phlox if you have one of those late frosts.

USDA Zone Info for Marengo

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 Marengo

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