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

You should be able to figure out when it's possible to plant tropical water plants by using the USDA zone info for Zone 4b.

Planting Calendar for Tropical Water Plants

Frost tolerance for tropical water plants:	Not tolerant of frost.
When to plant:	After the last frost.

It's a bad idea to plant tropical water plants until after all chance of frost has passed because they require warm weather.

The earliest that you can plant tropical water plants in Zone 4b is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant tropical water plants and expect a good harvest is probably August. Any later than that and your tropical water plants may not have a chance to really do well. Starting your tropical water plants indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 4b and it is different every year. Half of the time in Zone 4b you get a frost after May 15 so be sure to be ready to cover your tropical water plants if you have a late frost.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.