When to Plant Zinnia in Hamilton, MT

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.

The first chance to plant zinnia in Hamilton should be figured out by referring to the USDA zone info.


Planting Calendar for Zinnia

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

Since zinnia require warm weather it is necessary to wait until after the last frost has passed before you can plant them.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant zinnia
Possibly ok, but a risky time to plant zinnia
Probably not a good time to plant zinnia

The earliest that you can plant zinnia in Hamilton 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 zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your zinnia indoors.

Last Frost Date

The average date of last frost is April 15 in Hamilton. You can expect an average low temperature of -15°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Hamilton may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Hamilton you get a frost after April 15 so be sure to be ready to protect your zinnia if you have one of those late frosts.

USDA Zone Info for Hamilton

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Hamilton

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