When to Plant Cosmos in Arlington, WA

Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of making a decision about when it's possible to plant cosmos is to use the USDA zone info for Arlington.


Planting Calendar for Cosmos

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

Since cosmos do ok in moderate cold you can plant them a bit earlier in the year than more sensitive plants.

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

The earliest that you can plant cosmos in Arlington 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 cosmos and expect a good harvest is probably August. Any later than that and your cosmos may not have a chance to really do well. If you are starting your cosmos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Arlington the average date of last frost happens on March 15. It might get as low as 15°F during the coldest months of winter.

It's important to 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 Arlington and it will vary from year to year. Since half of the time in Arlington there is a last frost after March 15 be ready to cover your cosmos if you have a surprise late frost.

USDA Zone Info for Arlington

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 Arlington

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