Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By referring to the USDA zone info for Manhattan you should be able to estimate when it's possible to plant alternanthera.

Planting Calendar for Alternanthera

Frost tolerance for alternanthera:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since alternanthera require warm weather it's important to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant alternanthera in Manhattan is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant alternanthera and expect a good harvest is probably August. If you wait any later than that and your alternanthera may not have a chance to really do well. If you are starting your alternanthera indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Manhattan. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Manhattan is not always accurate the actual date of last frost will vary from year to year. Half of the time in Manhattan last frost occurs after April 15 so make sure that you are ready to protect your alternanthera in the event of a surprise late frost.

USDA Zone Info for Manhattan

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 Manhattan

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