Pruning Tips: Dogwood TreesI like the entire genus of dogw<:>,ods(Cornus). There is a

reason the old favorites are old favorites-they're nice. Thedogwood trees (as opposed to the dogwood shrubs and ever-so-cute but hard-to-grow dogwood groundcover) have niceflowers, and fall color. Many have berries and some have anelegant winter branch pattern.

WATERSPROUTSWith regards to pruning, the most important thing to know

is that dogwood trees throw watersprouts at the drop of a hat.(See Pruning Tips: Suckers and Watersprouts.) Prune toomuch (and it doesn't take much) and the next growing seasonwill bring a bushel basket of watersprouts growing from thesite of each cut. Watersprouts are the rapidly-growing, skinny,ugly, straight shoots that grow as a result of mal-pruning.Sometimes, they are erroneously referred to as suckers byNorthwest gardeners who also use it as a verb. They mightsay something like, "Boy, that dogwood sure suckered-backlike crazy!", which is easier to say than "watersprouted-back".With most trees, professionals advise that you could removeup to one-fifth of the foliage. But when pruning a dogwoodtree, I say you should prune even less. Maybe something likeone-eight of the foliage, or perhaps even one-sixteenth. If itdoesn't grow a bunch of watersprouts from the pruning cuts ina year's time, then you have not overpruned and you may trysome more. Or not, if you don't want to tempt fate.

BLEEDING AND TIMINGI am told dogwoods bleed if pruned too early in the year.

I have never seen this myself. When a tree "bleeds," it oozessap from a pruning wound at a scary rate. I have read thatbleeding does not hurt the plant, but it does bother the treeowner. The bleeding will stop once the tree's leaves emerge.For these reasons and others, one usually prunes in the earlydormant season or in summer.

SUNSCALDA dogwood's bark, especially the Eastern Dogwood (c.

Florida), is thin and prone to sunscald-another reason not tooverthin. I have heard a garden columnist advise people toshade the trunk by planting shrubs to cover it. But I think thisjust makes everything look crowded and messy. Iwould ratherpeople just retain enough lower limbs on the tree trunk itself,or, if not, try to see that that the tree is protected by the highshade of trees nearby. Dr. Alex Shigo (world famous treescientist) has stated that there is no such thing as sunscaldcaused solely by exposure to sun, not even on a dogwood. Hiswork indicates that the splitting bark (sunscald) is a result oftwo cuts being made one directly above the other, or byimproperly placed cuts, specifically flush cuts (which removethe collar). In either case, the "take-home" message is "avoidlimbing-up dogwoods" whenever possible.

GENERAL PRUNINGThat doesn't mean that you shouldn't prune. If a limb is

growing out into the pathway, prune it off to the collar, (seePruning Tips: Straight Skinny on the Life Of Limbs). Andcertainly take off any deadwood. It is easy to spot in thesummer because the dead branch has no live leaves on it. Oldpreviously mal-pruned or anthracnose-ridden trees will have

PRUNE OFFRUBBING/CROSSING

BRANCHES

plenty of deadwood. The greatest pruning secret is to removedeadwood. Good pruners do it first and do it always. We alsolook for any obviously broken or damaged branches.

SIZE CONTROLDo not attempt height control or reduction I It won't work.

Even with proper selective heading cuts (drop crotch cuts,see Pruning Tips: Basic Cuts) a dogwood tree will explode intowild regrowth of ugly watersprouts. Prune those off and threetimes as many grow backl

Only on the rare occasion is the selective heading cutused on a tree, especially a dogwood tree. I can remember .such a cut made on a previously mal-pruned Eastern (Florida)dogwood. The branch in question had been headed before andthe end of it sported a nasty snarl of watersprouts. It was notan option to take the limb off entirely because it was too largeand, in addition, the cut would have left an unbalanced-looking tree. So we followed the branch back from the tip to aplace where there was a large, well-placed lateral branch andcut back to there. The remaining cuts on the tree were all truethinning cuts, removing lateral branches at their point oforigin.

THINNINGMany of the remaining branches to be removed will be

located near the crotches. Pruning out small branchlets fromthe space nearest where the branches attach to the trunkseems to make the tree look more well-defined and cleaner.On many dogwoods, especially the Eastern dogwood(c. florida), the elegant branch structure can also be accentu-ated by taking out some (never all) the duplicating or parallelbranches. A branch of this species tends to have a smallerbranch attached to it that exactly parallels its parent. Pruningoff the "baby" branch (or the parallel part of it) may makeyour plant look better. See illustration. This sort of general

Remove parallel "baby" branch

10 - Fall, 2000

thinning is the artistic part of pruning,and is quite enjoyable. But be carefulnot to over-prune. And this is hard onceyou start seeing how much better it 'J

looks thinned out. The overriding law isto stay within the PRUNINGBUDGET,and remember, the budget is extremelysmall for dogwoods.

In general, you should work fromthe bottom up and the inside out, goingin a general upward spiral fashion.When confronted with a difficult pruningdecision, I have found it is best to skip itand move on. Just remove thosebranches you are quite certain need tobe removed and that will not leave alarge "hole". And know that yourfeelings of uncertainty, which some-times border on a mild form of terror,never really go away. Professionalpruners just learn to "push through it",Whenever I find myself paralyzed withindecision, I just move over to anotherpart of the tree. I know I can come backlater, after the rest is done, or when Ihave viewed it from many anglesoutside the tree.

SPECIES BY SPECIESThe Carnelian Cherry (C. mas)

Cornus mas is a plant lover's treebecause it blooms very early (February)with small, cheerful yellow flowers and,like forsythia, it blooms before theleaves come on. In the fall, the Corne-lian cherries have big red fruits reminis-cent of cherries (hence the name) It'salso a plant lover's tree because, well, itlacks structural grace. This is to say itsbranches tend to be skinny and straight,crossed like t's, and parallel all over theplace in a most unfortunate way. Onlyin great age do they develop morearching grace. Go easy on these trees.Pruning more won't make the branchesany prettier, and watersprout regrowthcould make it a lot worse.

The Eastern dogwood (C. florida)The Florida dogwood is a favorite

small garden tree. It comes with eitherpink or white flowers, and there areeven some with tricolor leaves. Theybloom in May. They have the classic"turban's cap" buds--good for winterIdentlflcetion purposes. They have goodfall color. And they have the elegantbranch structure I love to look at in thewinter. They are more densely branchedthat the Western dogwood (c. nuttallii)and shorter. Many of the Easterndogwood trees grow with a spreadingdouble-leader, which by the way should

not be corrected into a single-trunkedtree by people who have read moreabout pruning than they have experi-ence. They are also extremely prone toa nasty disease called anthracnose thatturns all the leaves crispy brown in thesummer and then fall off. Not all theEastern dogwoods have the disease.The healthy ones I see tend to be livingin tall open shade or mild sun asopposed to being tightly jammed in acourtyard. Good circulation is impor-tant. However, do not try to creategood circulation by over-thinning. Youwilljust cause a billion watersprouts toregrow and they really make it thickand prone to disease. On the otherhand, cutting down the Douglas fir nextto it can help. Ifyou are not adverse toa chemical program, there are thingsthat can be sprayed on the tree that willeffectively control the disease. Or youcan just learn to live with the sight ofcrispy leaves in the summer.

By the way, all the dogwood treeslook a little more drought-stricken thanthey actually are. In the summer, theleaves directly exposed to sun start tofold, looking roughly like Taco shells.This is normal, and is even an identify-ing characteristic of the tree. This is notto say it's okay not to water. It's justsomething to know.

Korean Dogwood (Comus kousa)The Korean dogwood seems to be

somewhat disease resistant (meaning itdoesn't get anthracnose as badly) andis quickly becoming a new favoritesmall street tree (for under powerlines).It can be a multi-trunk ed, twiggy treethat in older age develops a nicer, fan-shaped branching habit. Sometimes itblooms so heavily it pulls the limbsover. Very impressive. It is one of thetrees that, when Iwas first becominginterested in gardening, I actuallystopped the car and tracked down,going through several yards to find outwhat it was. (The others were Ginkgoand Paulownia.) The reason Iwasinterested was that it bloomed solidwhite in the summer (when mosteverything else was through blooming)and then FADED TO PINKI000001 Allthe girls will want one. The samepruning rules apply as with otherdogwoods.

Western Dogwood (Comus nuttallii)My favorite dogwood tree is our

native tree, the nuttallil, but I neverrecommend planting it because it is

extremely susceptible and defenselessagainst anthracnose. I've seen manytrees die from this and it makes me sosad. It is a much taller and more openlybranched tree than the Eastern dog-wood. Its flower bracts are a creamywhite, tinged slightly green. The flowersload up the trees in early spring andone can see why it is British Columbia'sProvincial Tree if you drive the countryduring the bloom time. They're every-where and they're beautiful. Andsometimes there is a second bloom inthe fall. They have, in my opinion thenicest branches, like delicate ripples ofwater. They also develop a nifty seedpod.

My opinion is not shared by all.When Iwas first learning gardening, Ifound two City gardeners in a Parks'Department truck. I asked, "What's thedifference between the Eastern andWestern dogwoods?" They agreed thatone was much denser than the otherand they both sald one was better thanthe other, though it turned out to be adifferent tree for each.

In an effort to simulate the feelingof a Western dogwood in my yard (butwithout the anthracnose problem), Ipurchased an Eddie's White Wonder, across between the Eastern and theWestern dogwood. I like it, though it'snot quite the same flower-bract. It doeshave lovely fall color and only gets alittle anthracnose at the bottom (wherethere is less air circulation). For severalyears Iwould go outside to find the topfoot of the tree broken, I never figuredout why, though I suspect a crow orsquirrel had something to do with it.Following each break, it would send upseveral new shoots, and I always felt Ishould be a good pruner and go up on aladder and train it back to a singleleader. But I found that if I just put it offlong enough, the tree would choose itsown new leader and the other competi-tors would subside into side branches.Now when people ask me if they shouldtrain a new leader on a broken top, I'mnot sure what to say. Sometimes youshould work on it (to prevent a doubleleader from developing) and sometimesyou can ignore it and it will go away onits own. I have found this to be true ofmany problems in life. The hard part ofproblem solving is knowing which oneis which.

(continued on page twelve)

PlantAmnesty Newsletter - 11

Pruning Tips: Dogwood Trees(continued from page eleven)

NEXTYEAR'S

~/

GROWTH ~...'

~E ~." ...

IT

IHEADING CUTNOW NEXT

YEAR'SGROWTHWILL BE--.I

THINNING CUTNOW

I

SELECTIVE (Drop Crotch)HEADING CUT

NOW

INEXTYEAR'S

rd/~-----~:I

REHABILITATIVE PRUNINGBecause dogwoods have such a

lovely branch structure and becausethey watersprout-back so horribly,gardeners consider the mal-pruning ofthem as particularly bad. The threecommon forms of mal-pruning aretopping, shearing into a ball or othershape, and over-thinning. The goodnews is that, given enough time, theycan be pruned back into good shape.But it's hard, and it takes nerves ofsteel. The overwhelming impulse is toremove all the ugly watersprouts. But

FAST THICK GROWTHFROM CUT UPWARD. ,..,.

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MORE GROWTHFROM TIPS

CONTINUATION OFGROWTH THROUGHEXISTING BRANCHES

that won't work, more just grow in theirplace.

The four steps to rehabilitativepruning are: 1}Wait, 2} Thin 3}Waitand 4) Thin. The waters prouts will shootway, way up but eventually arch overand turn into youthful, pretty decent-looking branches. The problem is theylook different than all the original oldbranches which are more curved andgenerally better looking. It is thecontrast between the two types of

branches that drives people crazy. Asa professional I have developed spe-cialty pruning which is done to mitigatethe intolerable contrast. This keeps thetree-owner caIrn long enough for thetree to out-grow the mal-pruning. It alsodoes help the tree regain its naturalshape sooner. Such pruning is counter-intuitive and it is very hard not to over-prune while working on the tree. It willtake five years or so before the tree isfully restored.

This is what you do: Take out all ofthe deadwood and stubs. Then wait ayear. Go back in and take out just AFEW of the watersprouts from some ofthe clusters along the branches. Takeout more of those closest to the branchcrotches. Wait another year. Now, beginto make the two branch types (the oldcurved and the new straighter) lookmore uniform. (A series of illustrationsfound in Pruning Tips: Abelias andSpireas shows it well.) Do this byremoving some of the pretty curvedbranches, leaving straighter old growth(that's the part that doesn't makesense). Then cut off some of the mostimpossibly ugly, long, or wrong wayshoots of the new growth, leaving theshorter more curvaceous new shoots.Now the top and the bottom, (or theinterior and the exterior) more closelyresemble each other. Only do SOMEOF THE PRUNINGNOW. Come backnext year or the year after and do more.One year you will come back andeverything will look pretty good. Ah...success.

If you are having difficulty identify-ing the tree as a dogwood, refer to theold horticulturejoke: Q. How can youtell a dogwood? A. By its bark. Just oneof our outstanding collection of cornyjokes here at P/antAmnesty ..•.

Dickson's Gardening Rule:

When weeding, the best way tomake sure you are removing aweed and not a valuable plant isto pull on it. If it comes out of theground easily, it is a valuableplant.

12 - Fall, 2000

RehabilitativePruning ForPreviously HeededSmall Trees andShrubs

Step 1-Remove some low hanging branches

)~

Step 2 - BeforeCut out a few of the most arching

(prettiest) branches, including interior,not just outward facing growth

Step 2 - After, (

)lShorten to a bud

or lateral

Cut tothe stem

Step 3 - BeforeDeal with Watersprouts

Step 3-AfterCrown is more uniform, top & bottom

J~PlantAmnesty Newsletter - 13