Before planting it is a good idea to find your USDA Zone info to estimate your garden 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 Havre should be used to figure out when it's possible to plant tropical water plants.

Planting Calendar for Tropical Water Plants

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

You really shouldn't plant tropical water plants until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant tropical water plants in Havre 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. You probably don't want to wait any later than that or else your tropical water plants may not have a chance to really do well. If you are starting your tropical water plants indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Havre the average date of last frost happens on May 15. It might get as low as -30°F during the coldest months of winter.

Always keep in mind that USDA zone info for Havre is just an average and the actual date of last frost will vary from year to year. Half of the time in Havre last frost occurs after May 15 so make sure that you are ready to protect your tropical water plants if you have a surprise late frost.

USDA Zone Info for Havre

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 Havre

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