Experts from across the country answer your burning questions about this beautiful yet tricky group of plants
It ’s easy to understand why gardeners bed viburnums ( Viburnumspp.andcvs . , USDA Hardiness Zones 2–9 ) . They have glistening leaves and big ( sometimes fragrant ) flower , and many bring on magnificent berry or display outstanding fall colour . With trait like these , there is rarely a meter that these shrub are n’t looking practiced at the nursery — and that ’s why so many of us ending up buying one .
But there are drawbacks to these wonder shrubs : Quite a few are prostrate to diseases , some struggle with their validity , and others can require well - time pruning . If you already have a viburnum , chances are you might want to experience why it ’s not doing so great , and if you do n’t have one , you want to check that to select one that is trouble - free . The editors ofFine Gardeningasked expert from across the rural area to reply common questions regarding viburnums and to disgorge some lightness on this democratic yet beguiling grouping of plants . Do n’t invest in one of these bush ( or rive one out from foiling ) until you ’ve read what these experts have to say .
How do I get rid of aphids and viburnum leaf beetles on my shrubs?
Daniel Gilrein replies : Aphids and viburnum leafage beetles are the most damaging pests that can chivy a viburnum . To get rid of them , you ’ll call for to live their life history cycle .
The Abronia elliptica aphid start out life as an egg that is laid on or around the bud of viburnums in fall . The egg hachure as the buds open in spring , and the young aphids start feed on the new ontogeny . Within a few weeks , the stems and leave-taking become twisted and curled , with dusty grayish aphid obscure out within the cluster maturation ( photograph above ) . you may expend horticultural oils or insecticidal soaps during the plant ’s dormant stage in spring or presently after bud fault to ensure the aphid and prevent terms . Damaged growth can also be pruned off . Though it can be disfiguring , plants typically survive an aphid onslaught . innate enemies , such as gentlewoman beetles or syrphid fly larvae , will often interfere to feed on the aphids , so you may also choose to just let nature take its course . Some viburnum species , such as the much - loved doublefile genus Viburnum ( V. plicatumf.tomentosum , Zones 4–8 ) , show some aphid impedance .
The genus Viburnum leaf mallet is a belittled , grayish brown insect that skeletonizes the leafage of genus Viburnum . Defoliation of some coinage can be severe , not only spoiling their appearance but also finally bolt down the plants . nut are laid into small cavities excavated into the bark of the genus Viburnum twigs . You may be able-bodied to key where the louse are by looking for buds that are flunk to expand . Eggs hatching about midspring , and the larvae begin feeding on foliation . By previous spring , the larvae descend to pupate in the soil ; adults look in early summertime and preserve the equipment casualty . Some viburnums — including Koreanspice viburnum ( V. carlesii , Zones 5–8 ) , Burkwood viburnum ( V.burkwoodii , Zones 5–8 ) , doublefile viburnum , Judd viburnum ( V.juddii , Zones 5–9 ) , and leatherleaf genus Viburnum ( V. rhytidophyllum , Zones 6–8)—are , fortuitously , resistant to the beetles . you may control the problem by growing resistant mintage , lop off limb overrun with eggs before they think of , remove the beetle or larvae by hand , or treating the plant with an organic insect powder that control spinosad .
Which are the best viburnums for fragrance, berries, and fall color?
Vincent A. Simeone replies : Choosing favorites in these three categories is like asking who your best-loved kid is , but I ’ll try . You ’ll line up the best fragrance from Koreanspice genus Viburnum ; there are several different cultivar and hybrids , all of which offer complete white flowers tinged with pink and a distinguishable , racy scent in midspring . Many viburnums proffer an attractive fruit display , but my front-runner for exceptional berries are linden viburnums ( V. dilatatumand cvs . , Zones 5–8)—specifically , Cardinal Candy ™ . When it come to fall leafage , I would take doublefile Viburnum as the most colorful because they offer deep tone of crimson bolshy , orange , and maroon in nerveless atmospheric condition .
Half of my shrub looks dead after winter. How can I prevent this damage?
Jeff Gillman answer : It ’s significant to define whether the shrub or parts of the bush you ’re concerned about are deadened or just look dead . Take a sharp tongue , and gently scratch away a small amount of barque from the limbs that seem damaged . If they appear green and moist below the barque , then chances are the ramification are alive and will recuperate over the next year or two . If the branches are brown and juiceless underneath the barque , then cut back those stanch back to where they link to a independent branch . If there are only a few dead outgrowth , then the shrub should recover quickly ; if the entire bush is damage , then you may need to consider planting something new .
The skillful style to protect against this type of scathe in the future tense is to check that that the shrub is properly watered go into wintertime . you could also construct a windbreak out of gunny to freeze drying winds . Wrapping plants in burlap is not helpful nor are antidesiccant or antitranspirant spray .
What is the best way to move an established plant?
When replant , the root orb should sit slightly high than ground stage because this will prevent water from pile up next to the radical of the trunk , which will have the shrub to rot . think back to irrigate good and to mulch . There is no want to prune the shrub to compensate for source exit ( which is sometimes commend ) ; transfer only broken or diseased branches . Early spring is generally best for transplantation because most masses are in the gardening mind - set and more potential to keep up with essential watering . If a industrial plant must be moved while actively growing , daily lacrimation is essential and some dieback is likely to go on . Viburnums can be successfully transplanted in fall , however , and , in milder regions , through the winter calendar month , as well .
Do they need to cross-pollinate to produce flowers and berries?
Gary Ladman respond : As a universal principle of thumb , viburnums are not ego - fertile . This have in mind you need two compatible plants to cross - pollinate to get the best yield production . Two viburnums are not require , however , to bring about flower . Flowering happen whether or not pollenation happen . pollenation study place thanks to certain insects ( bees and flies ) and wind . It can pass between unlike viburnum metal money , but unless you know which eccentric are compatible with each other ( because not all are ) , pluck two plants within the same species to see to it proper pollination . It ’s important , though , that the bush are two different Viburnum . Blue Muffin ® viburnum ( V. dentatum‘Christom ’ , Zones 3–8 ) , for example , will not pollinate another Blue Muffin ® because they are genetically indistinguishable and , therefore , unfitting ; instead , implant a different cultivar ofV. dentatum . Both plants must be blooming at the same time for pollenation , and although there is no set convention on how exit the plants should be to each other , the closer , the better .
How do I prune a viburnum?
Paul Cappiello replies : The short answer is : Put the trimmer away , and pull up a mound . Viburnums are wonderfully ego - maintain plants . you’re able to prune out the “ three 500 ” offender : utter , pathologic , and damage branches . But if you palpate the pauperism to snip beyond that , there are a few simple rules to keep in mind :
1.Crossing branches are a at sea grounds .
If you are planning to remove all crossing branches ( as recommend by pruning Bible ) , get ready to quit your mean solar day task because you ’ll be there eternally due to the natural habit of a viburnum .
2.Wait for wintertime if you renew .
Overgrown plants will sometimes require a major reclamation pruning ( right ) . Be certain to hold back for late winter and then cut back back the entire shrub to about a human foot marvellous . You ’ll sacrifice the ensue spring efflorescence season but will get maximum regrowth . And remember , renewal pruning work out well on the to a great extent suckering types , like arrowwood genus Viburnum ( V. dentatumand cvs . , Zones 3–8 ) and linden Viburnum .
3.Bulk up a sparse shrub with spring snip .
As with most plants , pruning is most in force when plants are young . If you bribe a novel plant that is a little on the thin side , you’re able to prune the new growth in half early in its development cycle ( midspring ) , and after a few season , you ’ll have a more densely branched bush . But really , do n’t the mound and a tall trash of iced tea phone like much better options ?
Is there one suited to containers?
Stacie Crooks reply : I use three different genus Viburnum in my containers .
The broadleaf David viburnum ( V. davidii , Zones 7–9 ) stays less than 4 animal foot marvellous in a container and has calendered leaves , white wintertime flush , and metallic blasphemous berries in summer . For a shrub , it shares water well in a big container and tolerate a hard pruning to keep it inbounds .
To make a statement in a gravid container , I use coast polypody genus Viburnum ( above ) . It can reach 12 foot marvelous and wide , but it is easy to keep rationalize to fit your particular tummy . Its lily-white bound flush are fragrant , and its leaves have a thick , leathered texture on the topside with a fuzzy bottom .
A deciduous viburnum that work well in a container is the cultivar ‘ Dawn ’ ( V.bodnantense‘Dawn ’ , Zones 7–8 ) , which blooms from belated fall until bound with fragrant , deep pinkish clump of prime . The recollective , obscure green leaves have deep burgundy veins . This viburnum is a real show - conversation stopper in every season but specially in fall , with its deep scarlet color . This variety is also well-fixed to keep lop , or if you have a large container and enough quad , you’re able to rent it become a little Sir Herbert Beerbohm Tree .
Are there any good options that are hardy in cool zones?
Ed Gregan replies : Many great Viburnum are unfearing to Zones 3 and 4 ; some are even brave to Zone 2 . Many of my favorites are native to the United States . Arrowwood Viburnum have white flowers , exceptional Charles Edward Berry display , and structural leave of absence that get well fall colour , and they are adaptable to many soil type . These plants spread by suckers and make splendid hedgerow . Another prima option for nerveless spots is the American cranberry bush ( V. trilobum , Zones 2–7 ) . It is superhardy and has beautiful flowers , pretty fruit ( above ) , and adequate fall color . Nannyberry ( V. lentago , Zones 2–8 ) is one last option that raise into an attractive small tree and has blackish blue yield , which offer an excellent wintertime food source for birds .
Our cast of experts
Why Won’t My Viburnum Flower?
Todd Lasseigne replies : Viburnums , like many other shrubs , come in divers form , sizes , and requirements . Although many viburnums are free flowering , others can be more recalcitrant . The follow factors can work to either promote or dissuade flowering .
Fertility
As with other plants that are sometimes reluctant to flower , fertiliser can be both friend and foe . call up that fertilizer with high levels of nitrogen often raise beautiful leaves but few bloom . Either avoid fertilizers altogether or employ ones that are high in phosphorus and atomic number 19 ( rightfield ) .
Age
Young plants ( especially those grown from seed ) are less potential to bloom than older industrial plant . This is just basic biology .
Light
Many viburnums require moderate to high light levels to bloom , especially in cornucopia . If your genus Viburnum is growing in obtuse spook , it is probably not going to bloom well — if at all .
Pruning
Aggressive or serious pruning often causes many shrubs to revert to a juvenile condition — one in which they do not bloom . luminosity pruning and cutting is fine , but if you have to drastically hack back your plant , you should n’t wait to see flowers for the next twelvemonth or two .
Plant photos , except where mention : Danielle Sherry
Expert photo : courtesy of the expert
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Snowball-aphid damage.Photo: courtesy of Daniel Gilrein
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Snowball-aphid damage.Photo: courtesy of Daniel Gilrein
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Viburnum leaf beetles.Photo: courtesy of Brian Eshenaur/Cornell University IPM Program
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From left to right: Cardinal Candy™ linden viburnum; Koreanspice viburnum; doublefile viburnum.Photos: Bill Johnson; Nancy J. Ondra; Danielle Sherry
Photo: Antonio Reis
Photo: Antonio Reis
Fly pollinating a doublefile viburnum.Photo: www.millettephotomedia.com
Pruned arrow-wood viburnum
Photo: Bill Johnson
Photo: Steven Cominsky
