Fall Color & Updated Tree List

By Marilyn Loser

Wow! What a show of fall tree color in Alamosa! In my 30 years in the San Luis Valley I’ve never seen such a glorious display. Golden trees have held onto their leaves far longer than usual due to calm winds, record high day-time temperatures, and mild (for us!) night-time temperatures. 

As I write, the young ‘Autumn Purple’ Ash trees at Walgreens (east and west sides) are a brilliant red-purple.  I walk in the area frequently and never noticed such vibrant fall colors in the past. I want one of these trees!

Equally splendid are the brilliant red ‘Autumn Blaze” Maples in Diamond and Zapata Parks, donated last spring by Lucy and Ed Adams and Jan Oen and Don Thompson. I look forward to even grander displays as they grow.

We planted ‘Autumn Blaze’ Maples in Cole Park this fall and the landscaping plan for the new City Complex includes ‘Autumn Purple’ Ashes. What wonderful additions to our city!

The Alamosa Tree Board is updating its Recommended Tree List.  To view the list go to http://www.alamosatrees.net,  mouse over the “Tree Lists” tab and then click “Board Recs.”

At Dean Swift’s suggestion, we removed Black Hills Spruce from the list.  Three were planted during Arbor Week 2009 on the west side of Carroll Park. They’re in full sun and Dean said they “break bud” too early. The new buds freeze, stunting the trees’ growth.  Instead of becoming stately conical, dense trees, they become contenders for the Charlie Brown prize.

The Arbor Day website says Black Hills Spruce can withstand winter lows of -50 F (zone 2).  However, our bone-chilling winter lows aren’t the problem.  The problem is occasional spells of warm spring weather that encourage buds to open – the buds are killed when the temperatures plunge later on.

According to Swift, a few older Black Hills Spruce, or closely related White Spruce, live in town. If they are planted in winter-shaded locations, the colder conditions might cause the spruce to break bud later and do well.

I have trouble identifying the Black Hills Spruce.  They can be similar in appearance to our state tree, the Blue Spruce.  However, with Swift’s help and by studying photographs I took, I’m getting better. The backyard of Evergreen Nursing Home has one Black Hills Spruce in the corner near the alley and the back parking lot.  It is flanked by several Blue Spruces.  Visit the blog at the Alamosa Trees website to see photos.

As Swift points out, “The cones are very small and occur father down the tree than is typical for Blue or Engelmann Spruce.  Also the cones scales are not serrated on the outer margin, and the needles are shorter.”

Growing evergreens can be a challenge in the San Luis Valley.  This may seem counterintuitive since the mountains around us abound in evergreens.  As mentioned in a previous column, temperatures in the surrounding hills typically aren’t as cold as on the Valley floor and don’t tend to plunge during bud break season.  While spruce and fir suffer from early bud break, pines suffer from winter sun glare.

I absolutely love Austrian Pines, have four of them in my yard, and see many excellent specimens around town.  Swift doesn’t share my enthusiasm. He says the trouble with pines in the Valley is that they suffer from winter sun glare.  If we have a lot of snow followed by bright sunny days, trees in full sun may warm up enough to break dormancy.  At sunset, the stress of rapidly cooling needles and rapid formation of ice crystals often results in tissue death.

This did happen to several of my pines the winter of 2008 when heavy snow was followed by warm, sunny days.  The trees have largely recovered, but would have done better if I had spread straw on the ground to cut the glare. I’ve heard of some people spraying pines with a waxy product that apparently keeps the trees from breaking dormancy.

Older trees don’t suffer as much. You might consider planting Austrian Pines in shadier areas such as on the north side of your home.  This also prevents the trees from shading your house in the winter, when sun rays provide much needed warmth.

We didn’t remove any other evergreens (only Black Hills Spruce) from the Alamosa Tree Board Recommended List, but we plan to provide additional warnings about evergreen vulnerability.

The Tree Board is working on a list of “Top 10” recommended trees for Alamosa. I’ll let you know as soon as it is compiled.  And no, Siberian Elms will not appear on the list!

Between every two pines is a doorway to a new world.” John Muir