One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of making a decision about when you can plant tropical water plants is to look at the USDA zone info for Grinnell.

Planting Calendar for Tropical Water Plants

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

Since tropical water plants do not do well in cold weather it's important to wait until after the last frost has passed before you can plant them.

The earliest that you can plant tropical water plants in Grinnell 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 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. 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 Grinnell the average date of last frost happens on April 15. It might get as low as -20°F during the coldest months of winter.

It's important to remember that USDA zone info for Grinnell is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Grinnell last frost occurs after April 15 so make sure that you are prepared to cover your tropical water plants if you have a surprise late frost.

USDA Zone Info for Grinnell

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Grinnell

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