What fir?

OK, it’s the middle of December so I get to indulge my passion for Christmas trees.  One of the most interesting projects I’ve gotten to work on during my time at Michigan State is a study to look at alternative species of firs (Abies spp) for Christmas trees and well as for landscape conifers.  Firs are fascinating trees that are distributed throughout temperate regions of the northern hemisphere.  There are about 50 species, many of which are important for timber, landscaping or Christmas trees.


For those of you that put off your Christmas tree shopping until the end (or want to start thinking about next year’s tree) here are three trees to keep an eye out for.


Korean fir Abies koreana We have several growers in Michigan that are now growing Korean fir.  It has relatively short needles that have a bottle-brush arrangement on the stem.  The color is often described as dark green, but I’d say the needles tend more to a true green or Kelly green with a silvery underside.


Concolor fir also makes a great landscape conifer

Conolor fir Abies concolor  I grew up in the Northwest so I always knew this tree as white fir until I moved to the Midwest.  In any case, it’s a great tree.  Long, soft-blue needles.  Depending on the seed source they can be as blue as a blue spruce.  The main draw-back here in Michigan is that concolor tend to break bud early, which makes them susceptible to frost damage in the spring.  Their citrus-like scent is hard to beat.


Danish growers compete for the best Nordmann fir in the “Fight for the Golden star” at their annual tree fair.

Nordmann fir  Abies nordmanniana  Denmark is the leading producer of Christmas trees in Europe and Nordmann fir is their principle species.  The Danes like Nordmann because of its deep, dark green color and natural form and symmetry.  Europeans don’t like their Christmas trees sheared so they rely heavily on genetics and selection to find trees that naturally have good form. We’re starting to see more Nordmann in the US, both here in the Midwest and in the Northwest.  Growers complain that the trees are slow-growing to start but I think some US consumers are looking for a more open, natural-looking tree and Nordmann can fill this niche.

Green mystery revealed

Another easy one, or else you guys are just too smart!  It is indeed a mistletoe.  Gold stars to KB, John, Kandi, and Deb, and an extra point to Jane for identifying the genus (Phoradendron).  I believe it’s Phoradendron bolleanum, an introduced species which parasitizes Cupressus arizonica (Arizona cypress).

In any case, I chose this puzzle plant in keeping with the holiday season!  Thanks for playing!

Of Worms and Fertilizers

Today I’m going to write about fertilizers and worms.  The purpose of this post is not to encourage you to use fertilizers.  I agree wholeheartedly with Linda’s post – we don’t need many of the fertilizers which we’re using.  Still, it’s important to know the facts about anything that you’re doing (or not doing) to and for your garden, and to do them (or not do them) for the right reasons.  With that in mind, I’ve been reading about worms and fertilizers for the last few days and wanted to let all of you know the basics of what I’ve been reading, because it is somewhat contrary to what many gardeners believe.

Before we begin let’s get one thing straight — worms are basically good for your garden and your plants in general.  We like them!

Over the years I’ve heard all kinds of comments about how inorganic fertilizer is bad because it kills worms or drives them away.  For the most part I’ve just accepted these claims as generally true because it seemed to make sense and I didn’t have a reason to study it further (I don’t write about worms much, and I’ve never spent any time doing research on them – still, I have to admit that this is no excuse for ignorance).  The only contrary words I’d ever heard spoken about the reality of what fertilizers do to worm populations had come from a soil scientist friend of mine who told me, in casual conversation, that he didn’t believe that fertilizers were bad for worms at all, except, perhaps in the very short term if they got some fertilizer directly on them.  Rather, he believed that, because fertilizers encouraged the growth of plants, fertilizer use would actually increase worm populations because it would increase their food supply.

After reading through a few papers it looks like my soil scientist friend was right.  Here I’m going to summarize my general impressions about these papers into a few sentences – not exactly fair because the relationship between worms and fertilizers isn’t completely straightforward – but hey, this is a blog!  Basically, if you add fertilizer of any sort to your soil you will ultimately increase worm populations because you will encourage the growth of more plant material.  More plant material, over the course of time, means more organic matter for worms to eat.  Generally organic fertilizers seemed to be preferred by worms (probably because they include lots of organic material along with the nutrients which they offer), but overapplication of fertilizer (organic or inorganic) could be bad for worm populations, at least in the short term.

So, in a nutshell, judicious fertilizer use shouldn’t affect worm populations negatively.  Still, why add fertilizer at all if you can avoid it?  Mulch and compost – worms will definitely enjoy that!

Fertilizers, crops and landscapes

Last week Jeff wrote about the dangers of using “balanced” fertilizers, especially in reference to phosphorus content.  Comments quickly followed about using fertilizers in many situations – on farms, in container plants, on trees – and so on.  One of the latest comments came from Nick and began “I don’t usually recommend fertilizer for perennials or woody plants to consumers. In most cases they aren’t needed.”  And this leads into today’s topic.

Many of the horticultural practices we use in our gardens and landscapes have, unfortunately, been derived from agricultural crop production.  Whether you’re growing a field of wheat, garden tomatoes, or containerized shrubs your goal is maximizing crop production.  By its nature, this is an unsustainable practice because it requires continual inputs of water and nutrients at higher levels than would naturally occur.

But this is not how you should care for landscape trees and shrubs, and why Nick’s comment was a good one.  You don’t need to routinely add fertilizer to these plants; they don’t need it to grow normally.  What we should be doing in landscapes is preventing nutrient deficiencies.  Once you have a soil test in hand, you’ll know what nutrients may be too low (or too high) and how soil pH will affect that.  For most of us, this may involve occasionally adding one of a few nutrients (most commonly nitrogen), or perhaps acidifying the soil to improve nutrient availability.

 How do you know when to add nitrogen to established landscape plants?  Let your foliage do the talking. If leaves are uniformly yellow, small and sparse, you might have a nitrogen deficiency.  This will be most common in the mid to late summer, when plants are growing most rapidly and competing with one another for resources.  Be sure this symptom is wide-spread, however.  If it’s just one plant showing deficiency symptoms, it’s probably not a landscape issue.


Cirque du Poinsettia

Last week I brought up the seasonal topic of poinsettias. There are so many cultivars to start with, it’ll make your head spin.  Twenty five new varieties were introduced in 2009 alone.  One
of the major breeders lists 36 RED varieties.

But for painting and glitter, growers
and retailers stick to “white” (actually a very pale yellow to cream –
see last week’s ‘Polar Bear’ post) or possibly light pink. The trend had a good start in Europe and crossed the pond in 2004. I

n 2005, I toured a Denver area greenhouse and saw my first air-brushed point. They were doing a specialty Broncos theme with bracts sprayed deep blue and orange and plopped into a football-shaped pot (with the season Denver’s having this year, I imagine sales are down).  The “team colors” theme is everywhere now.  Nothing says Christmas like maroon bracts (looked more like dried blood) with orange glitter – the interpretation of a Hokie poinsettia, available at our local Kroger. Different.  Please comment if you’ve seen a weirder color combo (are there Steelers ones yet?!).

Nationally, independent garden centers note they can’t keep pigmented points in stock, despite charging upwards of $9 more for a painted 6” point than a regular one. 

I'll have a bluuue Christmas without yoooooou

Blue poinsettias at McDonald’s Garden Center in Virginia Beach – a best-seller.

I’ve not seen any studies determining if the dye alters the post-harvest longevity or not; anecdotal evidence suggests it doesn’t have much effect. Just don’t splash them with water – the dye will run. Growers are careful to paint only mature poinsettias with fully-expanded bracts, or else suffer the poinsettia equivalent of bad roots (a la Lindsey Lohan). One of best-known of the poinsettia painters is at K&W Greenery of Janesville, Wisconsin.  The owners have carved out their high-end niche by employing an artist to do the air-brushing and glitter-sprinkling, treating each one as an individual work of art.  Art that will die in a heartbeat if you forget to water it, unfortunately. But the mother of all poinsettia growers/retailers in Ellison’s in Brenham, Texas. They’ve turned the season’s opening  each year into a hugely successful, candle-lit, wine-pouring party. The Today Show even stopped by a few years ago. The Ellison’s tree photo has been making its rounds on the internet for so long, I don’t even know who to credit.


Where's the damn partridge

Fa la la la la  (is that enough “la’s”?) 

Whether you take your poinsettias painted, straight up, or not at all – happy holidays!

Saving your ash

My earlier post regarding plans to replace the monoculture of ash trees at the Gateway Arch Monument in St. Louis, MO with a monoculture of Lindens prompted a question about options for treating ash trees for emerald ash borer.  This is a complex topic so I wanted make sure I had time and space to respond completely.


First, the best and most current source of information regarding treatments for EAB is the Multi-state bulletin “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer” which is available as a full-color .pdf on the EmeraldAshBorer.info website.  Anyone who lives in or near EAB-affected areas and is considering treating their ash trees should take the time to download and read this bulletin.


Here are some key points to consider if you want to save you ash:

It is possible to protect ash trees from EAB with insecticides.  There are several examples in and around the original core infestation area in Detroit where arborists have successfully protected trees since EAB first was identified in 2002.  There are two general options; protective cover sprays and systemic applications.  For most trees, protective cover applications will require professional application with specialized high-pressure spray equipment.  Most systemic application will also need to be applied by professional applicators, except for small trees that can be treated with soil drenches of systemic insecticide.  To date, the most effective systemic product is emamectin benzoate, sold under the trade name TREE-äge.  In various tests, emamectin has shown the highest level of control among products tested and is also the only product that consistently provides more than one year of control.  Imidacloprid is also effective as a systemic but will need to be re-applied annually for the best level of control.


The likelihood of successfully treating an ash tree declines rapidly once trees begin to show noticeable crown-die-back.  In certain cases, researchers have been able to save EAB-infested trees showing some crown die-back, but once 50% of the crown is affected the tree is likely a goner.


Once started, treatments will need to continue in perpetuity.  To me, this is the biggest factor homeowners need to consider if they’re thinking about treating their ash trees.  To the best of our knowledge, EAB is here to stay.  EAB populations may begin to decline once most of the ash trees in a region have been wiped out, but trees in woodlots and forests that have been killed will continue to sprout, providing host material to maintain an endemic population of beetles for the foreseeable future.  Systemic applications can provide control but the products will need to be re-applied every year (imidacloprid) or every other year (emamectin) to be effective.


Effectively treating trees larger than 4” in diameter will require applications by a certified pesticide applicator and may cost several hundred dollars per tree.  Homeowners need to carefully consider the cost of on-going treatments versus removal and replacement.


Mention of trade names does not imply in endorsement.  Read and follow label directions when applying pesticides.

Friday puzzle unrolled

I knew this one was pretty easy, but I have my reasons (below).  Gold stars to KB, Jim, John, and Dave for correctly identifying rolls of sod (and they do seem thin, Peter):

Yes, sod.  I dislike instant lawns; they never look good for very long, at least in my part of the country.  And getting rid of sod (as we have in our landscape) is a nightmare with that *%&$^ plastic mesh in which the grass is embedded.  It breaks up into little bits that are constantly coming to the surface.

I don’t have an axe to grind about lawns; my philosophy is that if you want a lawn and can afford to maintain it well, more power to you.  But what’s wrong with the old fashioned way of seeding a lawn?  Sure, it takes a few more weeks to "grow your own", but seeded lawns look more natural and last much longer.

Balanced fertilizers are usually out of balance

I’m in the midst of grading papers for my nursery management class, and something that I’m running across is an incredible number of papers where the students are recommending balanced fertilizers.  Why are they doing that?  Or maybe an even better question is, what is a balanced fertilizer?  A balanced fertilizer is a fertilizer which has three numbers which are about the same, like a 10-10-10.  The problem with balanced fertilizers is that they are much higher in phosphorus than what most plants need — at least in relation to the amount of nitrogen and potassium which plants need.  Especially here in Minnesota, where there is usually plenty of phosphorus in the ground, this extra phosphorus serves no purpose except to pollute waterways.  We have got to break the cycle of just assuming that a balanced fertilizer is the way to go.  I get to see a lot of soil tests from old agricultural fields where balanced fertilizers were used for years and years.  Usually 10-10-10.  What I usually see — with very few exceptions — are phosphorus and potassium levels which are either very high or off the charts entirely.  Phosphorus and potassium don’t move readily in the soil while nitrogen does, so every year that you add 10-10-10 in the appropriate amount for your plants needs for nitrogen you’re adding too much phosphorus and potassium.  Any extra nitrogen which you add will move through your soil, but P and K will build up year after year (and some will run-off into gutters and drains).  So what do I recommend?  I like a ratio of about 5-1-2 or 5-1-3 for an N-P-K ratio in a general use fertilizer.