One of the first steps you take when you are figuring out 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 figuring out when to plant oleander is to refer to the USDA zone info for Helena.

Planting Calendar for Oleander

Frost tolerance for oleander:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Oleander do not do well in cold weather which means that it's important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant oleander in Helena 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 oleander and expect a good harvest is probably August. If you wait any later than that and your oleander may not have a chance to grow to maturity. If you are starting your oleander indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Helena the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Keep in mind that USDA zone info for Helena is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Helena it frosts late in the year after May 15 so make sure that you are prepared to cover your oleander in the event of one of those late frosts.

USDA Zone Info for Helena

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Helena

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