When to Plant Alstromeria in Portsmouth, NH

The USDA Zone info is a great tool for gardeners to help us estimate 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.

The USDA zone info for Portsmouth should be used to determine when to plant alstromeria.


Planting Calendar for Alstromeria

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

Alstromeria do well in moderate cold which means that you can start planting them earlier than other frost tender plants.

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

The earliest that you can plant alstromeria 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 alstromeria and expect a good harvest is probably September. You probably don't want to wait any later than that or else your alstromeria may not have a chance to really do well. Starting your alstromeria indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Portsmouth the average date of last frost happens on April 15. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Portsmouth may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Portsmouth you get a frost after April 15 so always be ready to cover your alstromeria in the event of a surprise late frost.

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.