Wind is Always a Threat
Gardening in my mountainside neighborhood is a challenge just like so many other places in Alaska. In addition to the cool temperatures and neighborhood moose and rabbits, I have quite a bit of wind to contend with. We chose our property because of it’s remote location about fifteen minutes southeast of downtown Anchorage. Once off the highway it’s another ten minutes of climbing, winding roads. It’s a really quiet setting most days but occasionally the wind picks up outside and pummels the yard and house for hours or even days.
Before I began gardening, the wind was just a quirky hitch to an otherwise great neighborhood. But last spring when I decided to grow cut flowers, the wind suddenly became my biggest concern. Placing the flower beds directly behind the house seemed the safest way to to protect the plants from the wind. Unfortunately, this means that my flowers are shaded half of the day! Thanks to our long Alaskan summer days the plants still manage to flourish.
The edge of the red zone in the drawing below marked ‘Potter Marsh’ is roughly where I garden. The wind is typically from the east coming down from the mountains just like in this drawing. I like to keep heavy plastic planters filled with flowers on the front deck but several times a summer they get tossed off into the yard by the wind!
I am curious about how the elevation of a location effects a garden’s plant hardiness zone. Seems to me that on average I lose at least two weeks of viable gardening time due to cooler overall temperatures at 1100 feet. The web site “On the Snow” posted an article in March of this year titled “Does Elevation Effect Temperature?”. Author Joel Gratz wrote ” …the temperature decreases by about 5.4 degrees Fahrenheit for every 1000 feet up you go in elevation.” If that is truly the case in my location, the USDA Plant Hardiness Zone Map shows a five degree drop in temperature changes my garden from a 4b to the cooler zone 4a.
Average Temperatures for the Glen Alps Community
I found the following information on the summaries provided by the Glen Alps Road Weather Station in Anchorage. There are two stations that are slightly closer, but this station is the closest in elevation to my house and garden. Our property sits at about 1150 feet and the station is at about 670 feet.
Possible Growing Season
(32 °F is used here to determine frosts*)
Date of First frost: 90% probability 9/22, 10% probability 8/24
Date of Last frost: 90% probability 5/23, 10% probability 6/18
Freeze Free Period: 90% probability 76 days, 10% probability 115 days
Temperature Norms for years 1981 to 2010
Average Daily Temperature ( °F) May 41.5 ° / June 49.2 ° / July 52.6 ° / August 51.1 ° / September 43.2 °
Average Daily Maximum ( °F) May 47.7 ° / June 55.9 ° / July 58.2 ° / August 56.7 ° / September 48.4 °
Average Daily Minimum ( °F) May 35.2 ° / June 42.5 ° / July 47.0 ° / August 45.4 ° / September 37.9 °
Greenhouse Micro Climate
The chart below shows the actual temperatures in my greenhouse this summer from early June to today. Inside the plants enjoy an average daily temperature of 58.4 degrees. Now that’s a micro climate!
In comparison, this chart (below) shows Anchorage averages.
When Day Lengths are longer than 12 hours in Anchorage
In Anchorage, the days are longer than twelve hours between March 18 (12 hours 4 minutes) and Sep 24 (11 hours 58 minutes). I found the day length information at Time Date.com / Yearly Sun Graph for Anchorage.
Rainfall in my neighborhood
Average Rainfall (inches) May 1.03″ / June 1.18″ / July 2.29″ / August 3.55″ / September 3.90″
Daily Precipitation Data for Anchorage, or any city in Alaska, is presented in a really neat looking chart by SNAP all the way back to 1952! It was too big to include but I encourage you to take a look.