Before planting it is a good idea to find your USDA Zone info to figure out 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.

By reviewing the USDA zone info for Washington you should be able to estimate when it's possible to plant iresene.

Planting Calendar for Iresene

Frost tolerance for iresene:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

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

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

Last Frost Date

In Washington the average date of last frost happens on April 15. You should expect an average low temperature of -5°F in the coldest months of winter.

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Washington and it is different every year. Half of the time in Washington last frost occurs after April 15 so make sure that you are ready to protect your iresene if you have a late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Washington

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