When to Plant Phlox in Portsmouth, NH

One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of making a decision about when it's the best time to plant phlox is to examine the USDA zone info for Portsmouth.


Planting Calendar for Phlox

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

Since phlox do well in moderate cold you can plant them a little bit earlier in the year than other frost tender plants.

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

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

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Portsmouth. It might get as low as -10°F during the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Portsmouth and it will vary from year to year. Since half of the time in Portsmouth you get a frost after April 15 be ready to protect your phlox in the event of one of those late frosts.

USDA Zone Info for Portsmouth

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low-10°F
Highest Expected Low-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Portsmouth

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