What perennials can survive Alaska's warming? For starters, check out the updated USDA zone map.

What perennials can survive Alaska's warming?  For starters, check out the updated USDA zone map.

I'm proud to say that I worked for Howard Weaver. Well, not directly, because he never edited me, but he did allow these columns to appear in the Anchorage Daily News and I will always be grateful for that. I was just a small, insignificant, tiny cog in the jeweled clock of an organization he ran, and 47 years later, I'm still very grateful for that. I wear a pin that says “Write hard. Die free. I got it from him. I keep doing my best, Howard.”

(Howard Weaver, the editor who led the Anchorage Daily News through its turnaround years, has died at age 73)

This is not how I expected to start this week's column. What I want to write about, and what I will write about, is the USDA's recent announcement of a new plant hardiness zone map. It shows the low temperatures the area can expect during the winter. It is used to determine whether certain perennials will survive the winter in a particular location.

Every now and then someone asks me which plant hardiness zone we grow in. Back in the early days of this column, the answer I remember giving was Zone 3A, a low temperature range of -40 to -30 degrees Fahrenheit. I would definitely add a few things about it also being a change in daylight that the map didn't take into account; It was the temperature tracked by the government.

I can even remember it being used to access these temps. Remember, back in the days when we all had engine block heaters? For starters, winter is really getting warmer.

In fact, things have improved enough that in 2012 the USDA issued a new map. I can't remember exactly which zone we were in, but it was a little better so I would answer zone 3b and laugh, because the hike was nothing to write home about – even though it is a column. That was certainly an improvement, but not as much as any decent perennials we'd like to grow here would notice. After all, when it's cold, what's 10 degrees somehow?

Well, there is now a new Plant Hardiness Zone map for 2023. And once again it shows improvement. It has now been shown that most people who plant their gardens in Alaska do so in Zone 5B. This means that at some point during the life of a perennial or expensive tree, you can expect low temperatures of 15 to 10 below zero. This is almost survivable with many perennials. And hey, add a little protection from leaf mulch and snow, which will trap the heat, and all sorts of permanent possibilities really open up.

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Listen to the podcast “Teaming with Microbes” with Jeff Lowenfels and Jonathan White

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The fact that this new map was released so soon after the last update should put to rest any doubts about global warming. Things are definitely getting warmer. Just ask anyone who grows peaches in Georgia. Last winter was very warm by “normal” standards, and then there was a freeze and thaw as the plants bloomed; Goodbye peach crop. Alaska is losing salmon, so we know what that could mean for the economy and lives.

Now, don't get me wrong. For our purposes, there is still a problem with this type of scheme that may be unique to Alaskans. Even if a tree could survive our now much warmer winters, it would still be taller than most trees. Can this new tree also prepare for the rapid change in seasons? The length of our day varies dramatically, up to six minutes a day. At tree time, this may be impossible to manage. The leaves do not fall. Sugars do not get proper storage. A tree that should grow in zone 5b may not have the genes needed to actually develop into a spinard.

And this year, I'd be remiss if I didn't mention that there are also snow maps that need updating, at least as far as Alaska is concerned. I found one that said the average snowfall in Alaska is 64.5 inches. Hmm.

Jeff Alaska Park Calendar:

Alaska Botanical Garden: Have you seen the light show yet? Have you seen the lessons and workshops? Did you join and gift memberships as you suggested?

Snow Load: Oh my God. Are we unable to remove snow from limbs and bushes? Keep trying.

Indoor Christmas Trees: Water! Water and water. Make sure you are adjusted enough. And expect to recycle what you have thanks to ALPAR's annual recycling program.

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