Monday, February 8, 2016

Winter Pruning Punch List

Internet Photo from preservationtree.com
It's been unusually cold and snowy this winter.  That still works for gardeners who wisely use this time to focus on outdoor pruning.

Careful, correct, well-timed pruning will maintain tree and shrub health, beauty, value, and in the long run involve less, not more, maintenance. The goal is to enhance the plant’s natural shape and keep the branches headed in the right direction.

Dos:

  • Tree and shrub pruning can seem daunting: when to prune, how much to prune, what parts to prune and how to make the cuts?
  • Unless you’re skilled with pruning tools and balancing on tall ladders, schedule mature and older tree and shrub pruning now before bud break in early spring. Professional arborist credentials matter, so make sure they are International Society of Arboriculture certified.
  • If in doubt whether your trees or shrubs need pruning, consult with your arborist. Hire a well-trained, experienced professional, not a part time lawn care person. 


Prune crossing branches
  • DIY pruning on smaller fruit and ornamental trees (less than 25’) and shrubs should be completed prior to spring budding and flowering (usually early March).
  • Prune trees that tend to bleed sap later in spring, after their growth flush–maples, birch, and aspen. However, winter pruning will not harm sappy trees.
  • Prune these conditions at any time of the year – dead, diseased, crossed or rubbing branches, and hazard or structurally damaged limbs that may fall. Exceptions are trees prone to fireblight (apples, crabapples, pear, and hawthorns) – don’t prune in spring when the bacteria is most active.
  • Train by pruning trees when they are young to maintain the desired branching structure (two distinct habits)–one with a central leader (or single trunk) all the way to the top, such as linden, pines, aspen. Or trees that have a more rounded form with several secondary branches (scaffolds) that originate from the trunk like elm, maple and honeylocust.


    Internet photo from signaturekc.com
    • How much to prune trees depends on the age of the tree and how much it grows yearly. Rule of thumb – mature trees, prune 5-10%; medium-aged to small trees 10-25%. Generally no more than 25% of the live crown should be removed on any sized tree in one growing year.
    • Common types of pruning cuts (what parts and how much) include reduction cuts used mainly for young trees, and to reduce crown size where a larger branch or trunk is removed back to a smaller branch. Use heading cuts to remove leggy growing tips on young trees only and removal cuts on smaller branches (thinning) to open up the canopy and encourage growth. 
    •  
    Internet photo from ag.arizona.edu
    • Proper pruning for branches larger than one inch diameter is based on a three-cut method. 
    • The first cut is on the underside of the limb, one to two feet out from the trunk, one third to halfway through the branch. 


    Shrubs


    Internet photo from natureswayinc.com

    • Incorrect shrub pruning or pruning done at the wrong time may lead to deformed, weakened plants with fewer flowers, fruit or foliage. Avoid shaping woody shrubs into perfect mounds, squares or pompons.
    • When to prune is based on the shrub growth habit (mounding like spirea), cane (like forsythia), tree-like (viburnum) and flowering time.
    • Prune spring and early summer flowering shrubs like quince, forsythia, Nanking cherry, lilac, viburnum, weigela, honeysuckle, peashrub, and bridalwreath spirea right after blooming. Sometimes these blooming shrubs may need thinning or rejuvenation prior to bloom – realize some of this season’s flowers will be sacrificed. Prune Lilac After Bloom
     
    Pruning cane-type shrubs like forsythia, photo from Fine Gardening

    • Prune late summer flowering shrubs like potentilla, Annabelle and Peegee hydrangea, rose of Sharon, dogwood, burning bush, St. John’s wort, blue mist spirea and butterfly bush (Buddleia spp. and Cassia spp.) in late winter before bud break.
    • Branch anatomy will help you prune - shoots (branch growth after one season) on shrubs grow outward from their tips. Removing tips will stimulate any lower buds (undeveloped leaf, flower or shoot) to grow.
    • Two common types of shrub pruning cuts that affect future plant growth – thinning and heading cuts.
    • Thinning removes a stem or branch completely to the ground or to where it attaches. Thinning reduces shrub density and is used on crowded, tangled shrubs or shrubs with few flowers.
    • Heading is cutting a shoot or limb back to a bud or existing shoot– this promotes branching and bud growth. Which direction the top remaining bud is pointing will determine the direction of new growth. Prune ¼ inch above the bud, away and angled down, never too close to the bud or it may die.
    • Selective heading cuts reduce height, but maintain the natural shape of the plant.
    • In general, to create more shrub fullness, prune just above a bud pointing outward or away from the tree. To keep it narrow prune above an inward pointing bud.
    • Renew older or overgrown shrubs every year (for three years) by removing up to one-third of the thickest, oldest stems all the way to the ground. This opens the canopy allowing more air and light.
    • Renovation pruning is drastic removal of all stems back to six inches from the ground. This is done to promote better flowering and reduce plant size, but not for all shrubs. Try – forsythia, lilacs, barberry, spireas, mockorange, dogwood, flowering quince and privet.
    • Prune hedges in the shape of a pyramid instead of wider at the top for better light. Cut little, but often (after 6-8 inches of growth). More-Hedges
    • Use appropriate, clean and sharpened tools – bypass lopping shears (use on 1-1/2” branches) , pruning saw (2” or larger branches), pole pruning saw (hard-to-reach, high places), bypass pruner (small twigs).
    • Always wear protective clothing, safety glasses and gloves when pruning. 



    Whacked shrubs in late fall - Wrong time and not cut correctly!


    Don’ts:
    • Non-selective heading cuts or just whacking the top of the shrub (hair cutting) is a no-no except for maintaining hedges.
    • One trunk is best – when young, do not allow trees to develop codominant trunks where each trunk is about the same size and right next to each other, or V-shaped. These trees are prone to breakage or splitting from storms.
    • Never cut into the branch collar. This creates a flush cut and large wound that invites disease, decay and cracks.

    Never Top a Tree

    • Never top or stub a tree, or hire someone who does. Topping happens when the main vertical leader or other side and upper limbs are cut back to stubs. Topping makes trees look unattractive, weakens their ability to make food for healthy growth and leads to growth of excessive weak-wooded water sprouts.
    • Do not “lion-tail” prune were too many interior branches are removed leaving heavy weighted branch ends.
    • Never prune during freezing temperatures, tree damage to the cambium (inner cell area where water and nutrients flow) may occur.
    • Do not prune trees or shrubs that are stressed during drought periods.
    • Wound dressing sprays or paints are not recommended.
    • Evergreen trees and shrubs need little pruning. For pines, pinch off 1/3 of the new candle tips in spring to maintain compact or bushy growth.
    • Juniper and arborvitae pruning needs a soft touch, focus cuts back to where side shoots begin. Shearing is not recommended and never prune branches back to bare wood, that area will never grow back.

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