42. Last Frost Early Winter
A primer in garden terminology.
I want to plant lupine seeds. The seed package says 6 to 8 weeks prior to the last frost. The other seed package says to sow in late fall or early winter. Have I missed my window? Is it now too early? or too late?
Last Frost
Quick Answer: April 1st
Long Answer:
According to Almanac:
A frost date is the average date of the last light freeze in spring or the first light freeze in fall.
The classification of freeze temperatures is based on their effect on plants:
Light freeze: 29° to 32°F (-1.7° to 0°C)—tender plants are killed.
Moderate freeze: 25° to 28°F (-3.9° to -2.2°C)—widely destructive to most vegetation.
Severe freeze: 24°F (-4.4°C) and colder—heavy damage to most garden plants.
Ouch! We just got through a severe freeze last week. We had a few record breaking days with night time lows of 15°F and a high of 22°F . I did not realize this would be causing “heavy damage” to my garden plants. Drats.
Back to the last frost question, how does that get defined?
The National Gardening Association has First and Last Frost date tables per zip code. Here is 98366:
That’s a lot of dates.
According to the University of Washington Elizabeth C. Miller Library:
The last frost date in Seattle can be as early as March 22, but to be on the safe side, April 15-20 would be more definitive.
This article led me to Ed Hume’s site which states:
Most planting directions are based on the average last frost date […] of April 1st.
OK, so 8 weeks before my last frost date is Monday February 5th.
Early Winter
Quick Answer: November 16th - December 21st
Long Answer:
Winter starts December 21st and ends March 20th. Right?
That may be the winter season based on the Gregorian calendar, but then there is also something called a meteorological winter.
Meteorological winter includes the months of December, January, and February according to the NOAA National Centers for Environmental Information.
So what is early winter?
I was getting no where, and Google was no help.
So I asked ChatGPT. Here is what is said:
In gardening, the definition of "early winter" can vary depending on your location and climate. Generally, early winter is considered the period between late fall and the official start of winter. In the Northern Hemisphere, this typically falls in December.
Then I got more specific about the specific area where I live. Here is it’s response:
In [the Kitsap] region, early winter typically starts around late November and extends through December. The average first frost date […] is usually in late October or early November.
Then I asked how many weeks is early winter? Here is the response:
The duration of early winter is not precisely defined in terms of weeks, as it can vary based on climate, location, and regional weather patterns. Generally, early winter encompasses the period between late fall and the official start of winter, which is around late November to December in many regions.
If we consider early winter as extending from late November through December, it would typically cover approximately 4 to 5 weeks. However, the specific number of weeks can vary, and the transition from fall to winter is a gradual process influenced by local climate conditions.
Ok, so if I had to paraphrase this nebulous term, I would say the period of five weeks before December 21st.
So, am I too late?
Yes, I am both too late and too early to sow my lupine seeds.
My next step is to prep my seedling trays and mark my calendar for Monday February 5th!