Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Olympia should be read to determine when it's possible to plant watercress.

Planting Calendar for Watercress

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

Since watercress are barely cold tolerant you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

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

Last Frost Date

On average the last frost has passed is on March 15 in Olympia. You can expect an average low temperature of 10°F in the coldest months of winter.

It's important to remember that USDA zone info for Olympia is just an average and the actual date of last frost is different every year. Since half of the time in Olympia you get a frost after March 15 be ready to cover your watercress in the event of a surprise late frost.

USDA Zone Info for Olympia

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Olympia

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