One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of estimating when to plant delphinium is to examine the USDA zone info for Port Arthur.

Planting Calendar for Delphinium

Frost tolerance for delphinium:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant delphinium a bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant delphinium in Port Arthur is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant delphinium and expect a good harvest is probably September. If you wait any later than that and your delphinium may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your delphinium indoors.

Last Frost Date

In Port Arthur the average date of last frost happens on February 15. You can expect an average low temperature of 20°F in the coldest months of winter.

Since the USDA zone info for Port Arthur is not always accurate the actual date of last frost will vary from year to year. Half of the time in Port Arthur it frosts late in the year after February 15 so be sure to be ready to protect your delphinium if you have a surprise late frost.

USDA Zone Info for Port Arthur

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°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 25°F.

Plants to Grow in Port Arthur

You may be interested in your other planting guides for Port Arthur.