Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Isanti you can estimate when 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 do well in moderate cold which tells us that you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant tall phlox in Isanti is March. However, you really should wait until April 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 August. You probably don't want to wait any later than that or else your tall phlox may not have a chance to grow to maturity. 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

The average date of last frost is May 15 in Isanti. It might get as low as -30°F during the coldest months of winter.

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 Isanti and it is different every year. Half of the time in Isanti last frost occurs after May 15 so make sure that you are ready to protect your tall phlox if you have a surprise late frost.

USDA Zone Info for Isanti

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Isanti

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