Friday, November 1, 2013

Fall Color: Its Not Just for Broadleafs

Posted by: Eric Hammond Adams County

Front Range landscapes are thoroughly in the grip of fall. The leaves of many shade trees have changed color and are falling, vegetable gardens have mostly been put to bed, lawns have been aerated, sprinkler systems winterized and the deciduous conifers are losing their needles.

Fall Color of Tamarak (Larix laricina)
Ok, so maybe that last one is not exactly thought of as a hallmark of fall but it is an interesting side note to the season.

All conifers drop some needles annually. As the nights get colder and the days get shorter its completely normal for the inner older needles of temperate zone conifers begin to yellow in a less attractive parody of the fall color exhibited by many of their broadleaved counter parts. Different species hold on to their needles for different lengths of time. For example, Eastern White Pines (Pinus strobus) drop their needles after two years while Austrian Pines (Pinus nigra) normally hold on to theirs for four years. What makes the group of plants known as deciduous conifers unique is that, as their name implies, they drop all of their needles each year.

These plants can add a bit of fall interest and curiosity to a landscape when used correctly. I have always thought of them as the eccentric cousins of the more common spruces, pines and firs. There are several such conifers which can be grown along the Front Range. The most adaptable of these is European Larch (Larix decidua).

State Champon Eourpean Larch
The European Larch is a large tree which develops a more open habit as it ages. Under favorable conditions its needles can turn an attractive yellow before falling from the plants. The state champion tree is located in
City Park in Fort Collins and it is really worth seeing if you are in the area. While this species tolerates our climate and soils they are definitely not low water use plants. They are best used as either specimen or curiosity plants and could also be used in groups in landscapes that can accommodate their eventual large size such as parks, golf courses or large yards.

 Two other species of deciduous conifers which can be grown along the Front Range are Dawn Redwood, (Metasequoia glyptostroboides) and Bald Cypress (Taxodium distichum). From a botanical perspective (read: to a plant nerd) both of these plants are really interesting.

Dawn Redwood in the Fall

Dawn Redwood is a relative of the sequoias and at one point in time was native to much of the northern hemisphere including North America. The species was thought extinct until the early 1940s when a stand of living trees was found in a rural province of central China. Since then, Dawn Redwood has been reintroduced as an ornamental, with successful plantings from California to Maine and beyond.

Fal folliage of Dawn Redwood
As a landscape plant Dawn Redwood has a lot to offer. Plants are fast growers, have a soft and feathery texture and turn a very attractive orange-red in the fall. Unfortunately, in our climate they are best suited to protected microclimates and though they have some tolerance for higher pH clay soils they do best in better drained soils with a more neutral pH.

Bald Cypress is well known and valued for its ability to resist decay. The remains of large old growth trees are even harvested from the bottoms of swamps in the south east.

It is also a surprisingly adaptable plant given that it is native to swampy sites in the southeastern United States. It can be found growing in landscapes as far north as Canada. However, the species is even less tolerant of high pH soils than Dawn Redwood and must be sited carefully along the Front Range.

1 comment:

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