The USDA Zone info is a great tool for gardeners to help us figure out 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.

A way of figuring out when you can plant primula is to refer to the USDA zone info for Tomball.

Planting Calendar for Primula

Frost tolerance for primula:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since primula are very cold tolerant you can plant them much earlier in the year than other frost tender plants.

The earliest that you can plant primula in Tomball is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant primula and expect a good harvest is probably October. You probably don't want to wait any later than that or else your primula may not have a chance to fully mature. Starting your primula indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on February 15 in Tomball. It might get as low as 20°F during the coldest months of winter.

Since the USDA zone info for Tomball may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Tomball it frosts late in the year after February 15 be ready to protect your primula in the event of one of those late frosts.

USDA Zone Info for Tomball

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 Tomball

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