Birch question, any Tree People?

samiamvt(z4 VT)August 14, 2008


We have just had to really disturb/prune a lot of Birch roots to get the ground ready for an underplanting of perennial Geraniums. It is a small grove of Birches planted in the center island (approx. 38' x 18') of a circle driveway.

I am wondering what i can do to minimize the shock damage to the Birches. With another kind of tree I wouldn't be too worried and would just take the water to them, but I know that Birches are shallow rooted and don't particularly like to have their feet wet.

The soil in the island is mostly on the sandy side which is good, but we are having an extraordinarily WET summer.

Any suggestions? Xtra water or not? Xtra mulch maybe? or not?

The help is very much appreciated.

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georgez5il(z5 IL)

Have added soil (mix) to the area then planted in this ..... be extra careful NOT to place any extra soil/mulch with in 6 inches of the trunk....

    Bookmark   August 14, 2008 at 4:57PM
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If you really want to minimize damage to your birches, you should cut off the same percentage of foliage as roots you lost. That is, if you think you lost 30 percent of the roots, cut off 30 percent of the foliage. Most people find this hard to do. The strain on the tree is because fewer roots are trying to support the same amount of leaves and branches.


    Bookmark   August 14, 2008 at 6:24PM
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Actually, that is just the opposite of what you should do......both suggestions:-)

Adding soil of any significant thickness over the surface of the root system can have a very detrimental effect. First, you already have a root system under stress with the disturbance/removal of a lot of fine feeder roots. Anything much more than about 1 inch can serve to smother these disturbed roots (and can smother perfectly healthy, non-disturbed roots, as well). Mulch is quite different, as it is typically of a much larger particle size, allowing oxygen interchange with the soil and thus the roots.

Science supports the notion that rather than being a drain on a stressed root system, the foliar canopy actually assists and supports root regeneration. Reduction of the canopy only serves to slow the process, as there is less surface available for photosynthesis and so, less nutrient conversion (creation of sugars and proteins needed for regrowth).

Most trees can withstand some rather brutal root treatment pretty well. Removal of as much as a third of the root system can be tolerated for many species, including birch. The disruption of a quantity of mostly surface feeder roots common to attempting to plant perennials in this type of situation shouldn't have that negative an impact to the trees, especially if they are well-established. Just avoid creating any further stress by keeping them adequately watered for the rest of the season, by not pruning and by mulching appropriately to reduce soil moisture evaporation and moderate soil temperature.

    Bookmark   August 14, 2008 at 9:18PM
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gonativegal(zone 5a)

Dear Samia,

I would place this post in the Tree forum - there are some great tree experts over there.

- I have to disagree with gardengal and agree with jr - it is more prudent reduce the canopy especially during the summer months - this is what I've done when moving shrubs or small trees during less then ideal transplanting times. During very early spring, fall and winter this is not as critical.

    Bookmark   August 14, 2008 at 10:23PM
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You are certainly welcome to disagree all you want, but that does not negate the fact that pruning to reduce top growth at transplanting or when roots have been significantly disturbed is an archaic horticultural practice that has been proven scientifically to be counterproductive to the health of the tree and to the regenration of the root system. Time of year this is done it not critical.

Just because we "have always done it this way" does not necessarily make that practice right or horticulturally advised. There are a whole host of common gardening practices that research and scientific study have proven to be counterproductive or ill-advised and yet we persist in adhering to them just because we have always done so.

btw, as a professional horticulturist, I post and respond on many forums and I'd answer this question in exactly the same manner on the tree forum. Believe it or not, some of the very experienced hobby gardeners are up on the cutting edge of current horticultural practices - far more so than many pros, who seem to often get stuck in a rut of routine chores that really don't make a lot of sense but are "expected" or taken for granted. And of course, certified arborists that participate in continuing education to maintain their certification are well aware of and follow this no-pruning practice as well.

    Bookmark   August 15, 2008 at 12:25PM
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Mike Larkin

For what it is worth I agree with gardengal 100% - I guees it was not what they wanted to hear

"I am wondering what i can do to minimize the shock damage to the Birches" - my suggestion is to leave them alone and put the perennials some where else.


    Bookmark   August 15, 2008 at 1:02PM
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gonativegal(zone 5a)


What's so wrong with asking the tree experts over in the tree forum? Like you, I too am a horticulturist but I'm not above asking an arborist for advice. If they agree with me great, if not I learn something new.

I have to say it must be nice as a fellow horticulturist to have so much time to post in all these forums during the busy season. Myself, I'm too busy and tired for that other then a few minutes each night trying to learn something new.

    Bookmark   August 15, 2008 at 9:17PM
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There is nothing "wrong" about suggesting they visit there, however by doing so you make an assumption that no one reading the Professional gardening forum has the experience or background to give them a good answer to their request. Many professionals are "tree people" as part of their businesses as well and just as apt to have the correct info at hand as will the "experts" on the Tree forum.

There is always a risk when making assumptions in this type of venue :-) First, you have no idea what my business entails so have made an assumption that I should be too busy or too tired to visit GW, based, I guess, on your own experience. August is not considered the "busy season" here, in fact it is poorest month for business (retail and wholesale nursery sales, new landscape installations, design consultation, pruning, etc.) outside of February. The weather is too hot, too dry and too many people are traveling or on vacation this month. That's why all our regional trade shows are scheduled for this month - it's easier to get away from the business now than it is at any other time outside of the dead of winter. Added to that, I recently experienced a serious injury that prevents me from being very mobile and has drastically curtailed my outdoor activities. And I write a great deal for my business as well, so I am accustomed to spending large chunks of time on my computer as part of my normal course of business. All of these factors combined allow me the flexibility to visit GW as often as I wish - may not be your routine, but it is mine :-) Do you see how inaccurate making assumptions on limited information can be?

    Bookmark   August 16, 2008 at 11:25AM
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Exactly. When somebody gives a correct answer like gardengal did, there is no reason to tell them to go look somewhere else. Whether intentional or not, it indirectly says she doesn't know what she is doing. Asking a tree question on a professional gardener's site is an appropriate place, btw. It happens to me too Gardengal. You take the time to give a good, valid explanation and then the next poster replies like you don't know what you are talking about. I just say 'whatever' it's no skin off my nose. I don't think this was Gonative gal's intent, however. The tree forum is a very good site for all sorts of ?s about trees. However, since this is the pro site (or supposed to be) those answering should be knowledgeable enough to give accurate information.

    Bookmark   August 16, 2008 at 8:07PM
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gonativegal(zone 5a)


I made no such assumption. You assume I had an ulterior motive to stating that I thought it was nice you had the time to post here and elsewhere. I don't, I really do think it is nice that you have the time, and at the same time wishing I had more time - so call me a little envious. Though I suppose once I hit my off season and have too much time I won't be as envious, LOL.


Just because someone disagrees with you doesn't mean they don't think you don't know what you are doing. That is silly to say in the least. This is a forum, discourse and discussion are expected. You sound as if you take it personally when someone disagrees with you or offers up a different opinion, but it also makes it sound like you are saying that anyone who disagrees with you should just shut up and listen, as you know best. Is that really your message? I don't think it was your intent, but it does read that way.

There were various answers given to the original poster, so I suggested further sources of information, a place to post the question and get additional info and input. I am curious why anyone would think more info would be a bad thing?

    Bookmark   August 16, 2008 at 9:37PM
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petzold6596(8b southern NM)

Time to stop the banter!!!!!

    Bookmark   August 16, 2008 at 11:18PM
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Embothrium(USDA 8 Sunset 5 WA)

Methods researcher C. Whitcomb has a whole chapter in his 1987 (revised 1991) book Establishment and Maintenance of Landscape Plants on Top Pruning at Planting Time. It opens with a section called No Support for an Old Practice, and concludes (in part) with the statements

Arbitrary top-pruning has no place in modern horticulture


top-pruning to aid branch development and structure is a valid consideration

Many kinds of trees may need pruning and training when young to achieve a particular branching habit desired for specific uses. It seems the majority of kinds are best left alone for the most part once established on a site and displaying their basic permanent architecture. None are assisted by having both their roots and tops cut back at the same time. This method is used as an annual maintenance procedure for bonsai precisely because cutting the roots and tops back is so effective at dramatically reducing the amount of subsequent overall increase in size. Just cutting the roots back will dwarf the top of a tree until enough of the removed root growth is at least partly replaced. This is why newly purchased bare-rooted or field-grown* stock has a summer of short top growth the spring after purchase.

*Most balled-in-burlap stock has barely more live feeder roots left on it than bare-rooted stock

    Bookmark   August 17, 2008 at 5:32PM
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Embothrium(USDA 8 Sunset 5 WA)

"...the spring after purchase" was supposed to be "after being purchased in spring."

    Bookmark   August 17, 2008 at 5:35PM
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What a surprise. There is life on this forum.

Interestingly this encourages people like suzy and gardengal (pam?) and ron who have read the books and got the dirt under the fingernails to chime in.

Pruning a Birch whether newly planted or later is a special case. Read my book.

    Bookmark   August 17, 2008 at 6:06PM
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Now here is where a professional forum may be of use isn't it?

    Bookmark   August 17, 2008 at 6:31PM
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"You sound as if you take it personally when someone disagrees with you or offers up a different opinion."

Not hardly. And got nothing to prove, I made my fortune ;-), paid my dues and am sitting on my laurels until I can retire. Somebody else can battle the windmills.

I still check in once in awhile to see if there are any dirty fingernail people left around. I am a firm supporter of those who are starting up with backyard nurseries, but for the most part the forum doesn't address issues pertinent to my business anymore. As for taking in any forum, after you read the posts for awhile, you get a feel for who's been there and done that.

    Bookmark   August 17, 2008 at 7:04PM
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samiamvt(z4 VT)

I posted the original question here and I must say I never thought it would cause such a ruckus. This a forum and by definition everyone is entitled to express their views. If anyone even cares anymore about the situation in question, I'll tell you mine.
First of all, I am a Professional and I posted the question here because I wanted peer advice. (I thought about the Tree Forum but decided this was a better bet for experienced answers, plus the guidelines say that you should not post the same question in multiple forums, so I had to choose one)
Secondly Mike,("my suggestion is to leave them alone and put the perennials some where else") if you read the original post you will see that the damage to the roots had already been done when I wrote it. The underplanting is for a client, at their request and is an intentional and good design solution for a few reasons. The perennials were sourced specifically for that area, they were not just sitting around looking for a home.
Thirdly, I have done many plantings that have involved disturbing tree roots and am well aware that most trees are amazingly resilient and can take a lot of abuse (as gardengal pointed out). As I said in the original post, I wouldn't have worried much except that these were Birches (shallow rooted, prone to water issues) in a confined area in an exceptionally wet summer. That's why I decided to ask about it.
Finally, these are mature Birches and I (my company) am not an Arborist. I would have no means of pruning 1/3 of the foliage even if I were so inclined, which I definitely am NOT. I can see no benefit to stressing out the tree at both ends, especially in the middle of August. I am familiar with the old school idea of pruning foliage and roots, but I believe this applies more to shrubs, and to transplanting. And frankly, in my experience, it doesn't work all that well even in that case. That being said, I do absolutely appreciate everyone's input. Honestly.
I don't know about the moderators, but it seems to me that this is well on it's way to being it's own separate subject.
Again, if anyone cares anymore, we finished the planting on Thursday, with 100 Geraniums and a light dressing of mulch and instructions to the homeowner to water regularly if it doesn't rain.
With the Geraniums just starting to get a hint of their Fall color, it looks really, really nice.
Thanks again everybody, and play nicely.

    Bookmark   August 18, 2008 at 12:49AM
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Embothrium(USDA 8 Sunset 5 WA)

Probably the less rocky road would have been to place a coarse lightweight planting mix on top of the roots and plant the perennials in that, other factors being suitable such as adequate irrigation and the geraniums being a small enough size to fit in a comparatively shallow layer of added soil (and mulch). Birches produce a dense mat of thirsty roots and are likely to soon root into the planting pockets made for the flowers, and start giving them a hard time. Out here, with our droughty summers maintaining underplanting beneath birches of much size can be quite a chore.

Perhaps the tree should be cut for the fireplace at about age fifteen, for as it matures, the birch will shade out the lawn and its roots will starve underplantings

--Schenk, The Complete Shade Gardener (1984, Houghton Mifflin, Boston)

At this stage it appears I could water my paper birch grouping about every other day and it would not be too much. On a cooler, damper site (closest nearby frequently seen native groves occur north of here, on colder flatlands) it might be a different story.

    Bookmark   August 18, 2008 at 12:11PM
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rhizo_1 (North AL) zone 7

samiamvt, here's something else to consider in the future: the root systems of most trees are very shallow. It's the norm, rather than the exception.

Good going about the pruning, folks! Some myths are so slow to die.

    Bookmark   August 18, 2008 at 3:26PM
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I'd go with big pots in this situation. Blue pots with drought tolerant yuccas.

    Bookmark   August 25, 2008 at 12:18AM
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First question, what kind of birch?

And who told you birch were hydrophobic?

Since I am so late to coming to answer the question, it may be that it really doesn't answer, and depending on site specific conditions, my answer would be the same either way.

Water and a low nitrogen, high potassium (in relative terms) fertilizer. The exceptions would be if there are site specific circumstances, such as a hard pan that prohibits drainage or something similiar.

As to the endearing issue of root pruning/shoot pruning, most of my personal experience is in the form of bareroot from a wholesale supplier and attempting to turn it around for retail sales...what makes the most attractive plant the quickest, and that answer is not one that would be appreciated here.

I have no experience doing so in a landscape maintenance setting and will not speak to that.

    Bookmark   September 5, 2008 at 10:56AM
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Embothrium(USDA 8 Sunset 5 WA)

In most locations in regions with precipitation levels determined by storms coming off an ocean nitrogen is primarily what needs to be supplemented for best growth of trees, same as with other kinds of plants. A tree is just a big plant with woody superstructure, a sort of plant apartment building. At the outermost shoot tips and extreme root ends it is as delicate as an herbaceous seedling, with similar requirements.

People shouldn't be buying topped, hedge-like trees at garden centers anymore than they should be having them planted in parks and on landscape jobs. If a segment of a market seems to think shade and flowering trees offered them should be green meatballs that component of the buying public needs to be shown the light. Otherwise they are going to have problems with their mal-pruned purchases later.

    Bookmark   September 6, 2008 at 1:25PM
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OP wrote: "Birches.... don't particularly like to have their feet wet."
My experience is, just the opposite is true.

    Bookmark   September 13, 2008 at 4:49PM
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Good timing sam.

    Bookmark   September 13, 2008 at 5:44PM
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