One of the first steps you take when you are estimating 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.

A way of getting a good idea when it's a good idea to plant nasturtium is to look at the USDA zone info for Alton.

Planting Calendar for Nasturtium

Frost tolerance for nasturtium:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Nasturtium require warm weather which tells us that you need to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant nasturtium in Alton 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 nasturtium and expect a good harvest is probably August. You probably don't want to wait any later than that or else your nasturtium may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your nasturtium indoors.

Last Frost Date

The average date of last frost is April 15 in Alton. In the coldest months of winter you can expect an average low temperature of -10°F.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Alton and it will vary from year to year. Since half of the time in Alton there is a last frost after April 15 be ready to cover your nasturtium in the event of a surprise late frost.

USDA Zone Info for Alton

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Alton

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