Frost can be much later in outlying areas

In response to my recent post, “Is it safe to plant my tomatoes?”, Julien Nelson responded:

You say “now that the frost is over” WRONG Check with your paper’s Pat Timm. .
Sorry but I have lived in the  county since 1970. We keep careful records and April? No way. In the out lying areas we can have a frost through May even an occasional hail storm. 
There is a saying which works well. “If there is snow on Silver Star, don’t plant your summer plants” Look east it is still very snowy. Beside put your bare hand in a hole you dig, it’s very cold down there. Think about it. Plants planted too early get stunted and never grow well, ones planted later in warm soil, thrive and out grow earlier ones.
Yes, I know what I’m talking about, I’m a Master Gardener and CSA Farmer.
Good luck, J. Nelson
You are absolutely right Julien. Average last frost date taken at the Vancouver weather station is certainly not representative of outlying areas with much higher elevations and other microclimate factors. If you live in an outlying area, you need to factor in an adjustment, which can be as much as a month later. For most of us in the main Vancouver metro area (and similar areas in Portland and surrounding areas), we are probably past frost danger.
The point I was trying to make was that even without frost, tomatoes and other “summer plants” don’t make much growth until later in May unless you use some of the techniques I mentioned in the blog.
One other point to consider about frost date. Average frost date means 50% of the years there is frost after that date. I’m sure weather records will indicate much later actual frost dates than April 17 at the Vancouver weather station.
Weather and gardening is a topic with endless interest. Anyone else like to make a comment or observation?

Allen Wilson

Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.

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