When to Plant Tomatos in Washington, IA

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.

The first opportunity to plant tomatos in Washington should be determined by referring to the USDA zone info.

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Planting Calendar for Tomatos

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

Tomatos are not cold tolerant which tells us that it is important to wait until it warms up after all chance of frost has passed before you can plant them.

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

The earliest that you can plant tomatos in Washington 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 tomatos and expect a good harvest is probably August. If you wait any later than that and your tomatos may not have a chance to fully mature. You can get started a little bit earlier by starting your tomatos indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Washington. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Washington is just an average the actual date of last frost is different every year. Since half of the time in Washington it frosts late in the year after April 15 be ready to protect your tomatos in the event of one of those late frosts.

USDA Zone Info for Washington

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 Washington

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