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

By looking at the USDA zone info for Tomball it's possible to figure out when it's possible to plant dahlia.

Planting Calendar for Dahlia

Frost tolerance for dahlia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You can not plant dahlia until after the last frost when the weather gets warmer because they do not do well in cold weather.

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

The last month that you can plant dahlia and expect a good harvest is probably September. If you wait any later than that and your dahlia may not have a chance to grow to maturity. You can get started a little bit earlier by starting your dahlia indoors.

Last Frost Date

The average date of last frost is 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 is not always accurate the actual date of last frost changes from year to year. Since half of the time in Tomball you get surprised by a frost after February 15 be ready to protect your dahlia in the event of a surprise late frost.

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.