When to Plant Rhubarb in Mercer Island, WA

One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Mercer Island you can figure out when it's a good idea to plant rhubarb by reviewing the USDA zone info.

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Planting Calendar for Rhubarb

Frost tolerance for rhubarb: Tolerant of some frost.
When to plant: Up to 5 weeks before last frost.

You can plant rhubarb a little bit earlier in the year because they do well in moderate cold.

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

The earliest that you can plant rhubarb in Mercer Island 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 rhubarb and expect a good harvest is probably September. Any later than that and your rhubarb may not have a chance to really do well. Starting your rhubarb indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost is on March 15 in Mercer Island. You should expect an average low temperature of 15°F in the coldest months of winter.

Since the USDA zone info for Mercer Island is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Mercer Island last frost occurs after March 15 be ready to cover your rhubarb in the event of one of those late frosts.

USDA Zone Info for Mercer Island

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)March 15
Average Date of First Frost (fall)November 15
Lowest Expected Low15°F
Highest Expected Low20°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 20°F.

Plants to Grow in Mercer Island

You may be interested in your other planting guides for Mercer Island.