conifers – Page 3 – The Garden Professors™

Growing a greener Christmas tree

Among the many hats I wear, one of the most enjoyable is that of an Extension Specialist working with Christmas tree growers here in Michigan and surrounding states. I suppose part of the satisfaction stems from the fact that my first real job was shearing Christmas trees in southwest Washington during my high school summers. To give you an idea how long ago this was, the minimum wage when I started the summer between my sophomore and junior years was $2.20 per hour.

Today I’m involved in a variety of projects related to improving sustainability of Christmas tree production, particular water and nutrient management. One of our major focus areas has been the development of container production systems for living Christmas trees. For those not familiar with the concept, living Christmas trees are conifers that are sold with their roots intact as opposed to a cut Christmas tree. Living Christmas trees serve a niche market for people that think cutting a Christmas tree is wasteful or even harmful to the environment (never mind that virtually every Christmas tree cut in the US was grown on a plantation for that express purpose). Many Christmas tree growers have sold living trees by digging trees from their fields and selling them balled and burlapped or placing them in containers. In our current work we’ve focused on growing several species of conifers as container stock with the end goal as living Christmas trees. Container growing imparts a couple of advantage over the B&B method. First, container-growing eliminates loss of roots associated with field digging. Second container-grown trees are much lighter weight for consumers to handle than field-dug trees. Also, we have found the container-grown trees survive post-holiday storage and transplanting better than field-dug trees.

My former grad student, Wendy Klooster, shows off one on the Fraser firs she grew as part of her MS project on nutrient management.

If you’re considering a living Christmas tree here are some things to keep in mind.

If your ultimate goal is to plant the tree in your landscape, make sure the tree is a species that’s hardy in your location. There are several types of container-grown conifers such as Italian stone pine (Pinus pinea) sold in big box stores and super markets that are hardy in only the warmest parts of the country.
Limit display of living trees to 10 days to two weeks. Most conifers will begin to lose dormancy shortly after being brought indoors. We’ve observed that some, such as Black hills spruce (Picea glauca var. densata), will break bud if the weather has been cold and they’ve had sufficient chilling.
After the holidays, place the living tree in a protected but unheated space such as a garage or enclosed porch or patio. The key here is that the tree needs some exposure to light – but avoid direct sun.

As with just about everything these days, the environmental friendliness of Christmas tree production is receiving increasing scrutiny. One way to have the ‘greenest’ tree on the block is to bring home a tree that keeps on giving.

The World According to Chub

Following up on Holly’s theme of “I can’t believe I get paid to do this”, last Wednesday I participated in a walk-through and inspection of the Justin ‘Chub’ Harper Collection of Dwarf and Rare conifers at MSU’s Hidden Lake Gardens in south central Michigan. The Harper collection is widely regarded as one of the premier collections of rare and unusual conifers in the world.

Harper Conifer Collection with fall color background. Photo: Jack Wikle.

A little background: Chub Harper was the former grounds supervisor for John Deere’s world headquarters in Moline, IL, an avid plant collector, and a founding member of the American Conifer Society (ACS). He acquired hundreds of rare and unusual conifer specimens around his home and eventually had to lease a nearby lot for the overflow – demonstrating that ACS also stands for ‘Addicted Conifer Syndrome’. In the early 1980’s Chub donated 300 conifers to Hidden Lake Gardens to establish the Harper collection. All of the plants were balled and burlapped by hand and shipped in three semis to Michigan. Chub continued to add plants to the collection and today the collection includes over 500 accessions.

Chamaecyparis pisifera ‘Filifera aurea’

I met Chub about 8 years ago and with his guidance and inspiration started a series of ‘Conifer Corner’ articles in the Michigan Nursery and Landscape Michigan Landscape magazine. (visit my faculty page for .pdf’s of some sample articles http://www.hrt.msu.edu/bert-cregg/pg5). Once or twice a year Chub would travel from Moline to Michigan to inspect the collection along with members of his conifer posse. To me, the most impressive thing about the walk-throughs was how absolutely ruthless Chub was in disposing of under-performing plants or plants with continual pest problems. “Time for that thing to take a ride on the chipper truck” was a favorite Chub-ism. Hidden Lake Gardens has a garden staff that could spray pesticides or prune away dead material regularly; but Chub wanted none of it. This is not to say that Chub was into organic gardening; as far as I know he had no particular aversion to chemicals. Rather, he felt the mission of the collection was education and that maintaining plants in an artificially superior condition would mislead the public into thinking some conifers were better suited than they actually were.

The Conifer posse at the 2007 walk-through. Chub Harper is 3rd from left, back row.

Chub passed away unexpectedly earlier this year and last Wednesday’s walk-through was the first evaluation of the collection without him. The conifer posse carried on, led by former ACS President Dennis Groh; Chub’s longtime friend Jack Wikle; and Sam Lovall, the landscape architect who developed the original design for the collection. We found homes in the collection for several new specimens including an Abies concolor ‘Charmin’ Chub’ and condemned a few underachievers to a ride on the chipper truck. Chub left many legacies; the most obvious and tangible is the Harper Collection and the staggering generosity it represents. Imagine dedicating half your life to acquiring and cultivating a world-class collection and then simply giving it away. Just as important, however, is the legacy he left with those who knew him, who felt his passion for conifers, and were inspired by him.

Pinus parviflora ‘Cleary’

Carrot-top syndrome in white pine

I know a few folks out there are starting to believe that I’m just an apologist for the nursery industry. While it’s true most of the nursery people with whom I work are hard-working folks trying to do their best to run a successful business and produce a quality crop, there are certainly some issues out there and I’ve got my share of pet peeves. One of the things really that chafes my heiney is what I refer to as “Carrot-top” syndrome in eastern white pine (Pinus strobus). White pine is one of the most commonly planted conifers in this part of the world. White pine is native throughout much of the eastern US and is an extremely fast growing tree that makes a good ornamental when planted on the right place with room to grow. It is also widely grown as a Christmas tree in the Upper Midwest as well and therein lies the rub. Many nursery producers also grow Christmas trees and many Christmas tree growers also dig nursery stock. The result? White pines that have been heavily sheared as Christmas trees end up planted as landscape trees. Once in the landscape, the upper portions of the trees will quickly resume rapid growth, with some shoots growing 2’ to 3’ or more per year; while the side shoots that had been repeatedly sheared barely grow at all. After a couple of years the net result is neatly trimmed Christmas tree with a wooly beast growing out of its top. What’s the solution? Ideally producers should identify which portion of their trees will be sold as Christmas trees and which are destined for the landscape trade. Christmas trees can be sheared to meet demands of that market while landscape trees can be pruned much more lightly to maintain a single leader and conical form but keep obvious layers of whorls. The dilemma, of course, is that growers don’t always know which trees will end up and the Christmas tree lot and which will be dug for the nursery trade. The other, more challenging problem is that, given a choice, 99 out of 100 garden consumers will choose the neat-looking Christmas tree for the landscape, unaware of the wooly mess that’s about to be unleashed in their yard. The solution? Education on both sides; making growers aware of the issue and making consumers realize that the only way to have a natural-looking white pine in your yard is to start with a natural-looking white pine.

Heavily sheared pines will retain the outline from from shearing for years while the top rages out of control.

EverGreen or EverYellow?

In last week’s post I mentioned that many tree problems can be difficult to diagnose and require a thorough inspection and site analysis to get to the root of the problem. In contrast, a recent issue that has generated a lot of calls is easy to explain and is not a cause for major concern. Many homeowners and others are alarmed that needles on their white pines are turning bright yellow.

“Is my pine dying?”

The key in assessing this situation is looking at which needles are turning color. Except for southern pines, most conifers produce only one, single flush of new needles each spring. Because of this, we can work our way down a shoot and tell when each group of needles was formed. The outermost needles were formed in the current year, needles in the next internode were formed the year before, needles formed in the next internode were formed the year before that, and so on. Most evergreen conifers keep their needles for 3-6 years and then the needles senesce and fall off. The longest-lived needles, perhaps not surprisingly belong to bristlecone pines, which are also the longest living trees on earth. Bristlecone pines, the oldest of which is over 4,500 years old, have needles that persist for 13 to 17 years. But I digress, back to the white pine. White pine needles last 2 or 3 years. Each fall, many of the previous year’s needles turn yellow and senesce. Since the needles often turn bright yellow and almost half the needles on the tree are affected it can certainly grab attention. As long as only older needles are turning, the process is natural and there’s no need for concern. On the other hand, if this year’s needles are dropping that’s another issue and warrant further investigation.

White pines don’t keep their needles very long. As long as this year’s needles aren’t senescing, the tree should be OK.

Pining to learn more about conifers? The Gymnosperm database http://www.conifers.org/ is an awesome and authoritative site that has information on just about every conifer known to science.