Thursday, December 1, 2011

When to Prune Flowering Trees & Shrubs

Crape Myrtle 'Muskogee'
When is the proper time of pruning for flowering trees and shrubs? Part of the answer depends on whether the time of flowering is in the early spring or later in the season. As a general rule of thumb, prune flowering trees and shrubs immediately after flowering. 

Pruning correctly is important in maintaining the health and vigor of your landscape plants. Proper pruning helps to maintain the shape and form of your plants, helps to remove any unwanted growth, allows for the removal of any diseased or broken branches and helps to stimulate new growth and better flowering.   Not all trees and shrubs require regular pruning but if implemented it should be done correctly and at the right time of year (See Listing Below).


Pink Flowering Dogwood
Early spring bloomers formed their buds in early fall the season before on old wood. Pruning these plants before flowering in spring will result in cutting off the buds and decreased bloom.  Varieties of trees and shrubs that bloom earlier in the season (prior to the end of June) should be pruned immediately after flowering in late spring/summer. These plants include:  Flowering Dogwood, Forthysia, Flowering Crabapple, Flowering Cherry, Flowering Plum, Vibernum, Weigela, Magnolia, Wisteria, Mock Orange, Lilac, Rhododendron, Azalea and Bigleaf Hydrangea (Hydrangea macrophylla).

Trees and shrubs that flower after the end of June develop their buds on the new wood of the season and should be pruned in late winter to early spring (late March-early April). During this time the trees are dormant and it is easier to see before new growth starts.  Since these varieties form buds on the new wood of the season they can be pruned before buds set.   Examples of flowering shrubs that should be pruned while still dormant include:  Crape Myrtle, Bradford Pear, Buddleia (Butterfly Bush), Knock Out Roses, Stewartia  Abelia, Spirea (except Bridal Wreath) and some varieties of Hydrangea such as Peegee (Hydrangea paniculata ‘Grandiflora’) and Endless Summer Hydrangea macrophylla 'Bailmer').  'Annabelle' also blooms on new wood and can be pruned in early spring.

Often hardwood trees will sprout straight vertical branches from the base of the plant or roots called "suckers" or "water sprouts" that can interfere with the growth of other parts of the tree.  I often find it to be much easier to prune off these shoots while the tree is still dormant and the framework of the tree is visible.  This procedure is best done in late winter/early spring (late March).   If done later than November or December, pruning could spark the  tree to develop new growth that would not have enough time to "harden off" before winter.   Crape Myrtles and Magnolias are two trees that do not require much routine pruning but frequently send up "water sprouts".  Even though you may be tempted to prune these growths in late fall, resist the temptation and wait until late winter/early spring when it is healthier for the tree.


Rhododendron
PRUNE IN LATE SPRING (After Bloom):

Flowering Dogwood
Forthysia
Flowering Crabapple
Flowering Cherry
Thundercloud Flowering Plum
Vibernum
Weigela
Magnolia
Wisteria
Mock Orange
Lilac
Rhododendron
Azalea

PRUNE IN SUMMER (After Bloom):

Hydrangea 'Nikko Blue'


Bigleaf Hydrangea 'Nikko Blue'
Miniature Hydrangea 'Pia'

Hydrangea 'Peegee'
PRUNE IN LATE WINTER /EARLY SPRING (While Dormant):

Crape Myrtle
Bradford or Cleveland Select Pear
Butterfly Bush
Knock Out Roses
Stewartia
Abelia
Spirea (except 'Bridal Wreath')
'Peegee' Hydrangea
'Endless Summer ' Hydrangea
'Annabelle' Hydrangea



Flowering trees and shrubs are a wonderful asset to have in your garden and with proper maintenance they will continue to add years of bloom and color to your landscape.

As Always...Happy Gardening!


Author: Lee @ A Guide To Northeastern Gardening Copyright 2011. All Rights Reserved.




10 comments:

  1. Thank you for this information. It often gets confusing trying to remember what gets pruned when so I will keep this handy! ~ Donna

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  2. Really good and helpful post. I like how you listed them by pruning times too.

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  3. I really appreciate your efforts in maintaining our web site and helping us, I am sure you have a great team working out with you.
    Home Services

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  4. This is the first time I've heard someone classify what those odd straight vertical branches are. I had no idea that they had a name just before I came here. I used to never prune those parts up until recent years, I kept a few but usually chop off a good amount. What would you recommend? Is it best to really leave it all time around till spring?

    -Ken Nicely

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  5. Hi Ken,

    It is best to completely remove those vertical "water sprouts" since they draw strength away from the tree. The best time to remove them is when the tree is defoliated
    and it is also easier to see. As far a s the ones that sprout up from the ground, I remove them as soon as I see them-anytime.


    ~ Lee

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  6. Wonderful diagram on pruning and branch differentiation, it really helps out for the beginner green thumbs out there.

    -Asheville Tree Service

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  7. it is a nice day her on long island and I never got to go out and prune my roses lilacs and Hydrangeas if I went out there today would it be ok to do them?

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    Replies
    1. Hi Tara. Just got in and saw you message so I hope I got to you in time. Lilacs should be pruned in late spring after bloom. Hydrangea and Roses should be pruned in late summer/early fall. Pruning now in late November could spark new growth on your roses and cause damage to your plants with the cold and only hydrangea that bloom on new wood of the spring can be pruned now. I would wait until late winter/early spring at this point.

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  8. Hello,
    We have a double flowering plum that blooms around June (mid to late) and when its done, we prune it back into a nice round shape. It is August now and it is sending out new growth everywhere. Can we trim this new growth ?

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    Replies
    1. Absolutely. As long as you give it enough time to harden off before winter it is fine to prune. You have about a 4-6 week window of time right now.

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