One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant tropical water plants in Zone 4a can be figured out by looking at the USDA zone info.

Planting Calendar for Tropical Water Plants

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

Tropical Water Plants are not cold tolerant which tells us that you must wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant tropical water plants in Zone 4a 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 grow to maturity. You can get started a few weeks earlier by starting your tropical water plants indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Zone 4a. In the coldest months of winter you should expect an average low temperature of -30°F.

Keep in mind that USDA zone info for Zone 4a is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Zone 4a last frost occurs after May 15 be ready to cover your tropical water plants in the event of one of those late frosts.

USDA Zone Info for Zone 4a

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 Zone 4a

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