Minnesota Nursery and Landscape Association (MNLA) Foundation 15_Pruning_ppt.doc

LANDSCAPE AND TURF MANAGEMENT LESSON 15 - PRUNING

Overview Definition of Pruning Reasons for Pruning When to Prune (timing) Pruning Tools Rules of Pruning Apical Dominance Pruning Techniques 15_Pruning_ppt.doc

Definition of Pruning A horticultural practice involving the removal of portions of a plant to control growth, form and size, correct structural defects, improve health, vigor and structure, and enhance flowering and fruiting. The removal of plant parts for a purpose. Because plant parts are removed, pruning initially decreases the size of a plant, but can revitalize plants and ultimately stimulates new growth. 15_Pruning_ppt.doc

I. Reasons to Prune Young trees are pruned to encourage proper development and natural form and to create a well- spaced, sturdy set of scaffold branches. These branches are the basis for a strong and well-structured crown. Older trees are pruned to maintain their natural form and vigor; dead, dying, diseased, rubbing/crossing, and broken branches are removed. 15_Pruning_ppt.doc

I. Reasons to Prune To repair damage (damage from storms and other types of mechanical damage). To direct or control growth; except for mowing grass, controlling size should not be a primary reason for pruning (if extensive and repeated pruning is required to keep a plant from getting too big for a given location, it is the wrong plant and it should be replaced). 15_Pruning_ppt.doc

I. Reasons to Prune To encourage flowering and fruit production and to improve fruit quality. To create specialized or unique forms (e.g., topiary, espalier, bonsai). During production, root pruning is used to create compact, well-branched, transplantable root systems. To remove dead/faded flowers (deadheading). 15_Pruning_ppt.doc

I. Reasons to Prune Topping of older trees to reduce size and wind resistance is never an acceptable practice; the natural form is destroyed and the result is unsightly and increases the potential for internal decay and increased storm damage; topped trees are likely to become hazard trees. 15_Pruning_ppt.doc

When to Prune Late Winter (dormant season) Spring Summer Fall 15_Pruning_ppt.doc

Prune in Spring Plants that bloom in early spring on old wood (last season’s growth): (Prune just after flowering) Amelanchier spp. Serviceberries/Juneberries Forsythia spp. Forsythias Lonicera spp. Honeysuckles Magnolia spp. Magnolias Prunus spp. Cherries, Plums, Apricots, etc. Rhododendron spp. Azaleas and Rhododendrons Ribes spp. Currants, Gooseberries Spiraea spp. Spring blooming Spireas (white) Syringa spp. Lilacs 15_Pruning_ppt.doc

Prune in Late Winter or Spring Plants that bloom in late spring/early summer on old wood (last season’s growth): (Prune before growth starts in the spring or just after flowering) Philadelphus spp. Mockoranges Potentilla spp. Shrubby Cinquefoil Rosa spp. Some Shrub Roses Viburnum spp. Viburnums Weigela spp. Weigelas 15_Pruning_ppt.doc

Prune in Late Winter or Early Spring Plants that bloom on new wood (current season’s growth): (Prune before growth starts in the spring) Clematis spp. Clematises Clethra alnifolia Summer Sweet Hydrangea spp. Hydrangeas Rosa spp. Some Shrub Roses Spiraea spp. Summer Blooming Spireas (pink) 15_Pruning_ppt.doc

Prune in Late Winter or Early Spring Plants that are primarily grown for their foliage: (Prune before growth starts in the spring) Euonymus spp. Euonymus Ribes alpinum Alpine Currant 15_Pruning_ppt.doc

Prune in Summer Plants that “bleed” sap if pruned in winter or early spring: (Prune in summer) Acer spp. Maples Betula spp. Birches Gleditsia triacanthos Honeylocust Juglans spp. Butternuts, Walnuts Ostrya virginiana Ironwood Ulmus spp. Elms 15_Pruning_ppt.doc

Late Summer/Fall Pruning In general pruning should be avoided in late summer and fall; pruning at this time of year can sometimes stimulate new growth that may not harden off in time for winter and may be injured by winter temperatures. Broken branches can be removed at any time during the year including during the fall. 15_Pruning_ppt.doc

Prune in Winter Plants whose susceptibility to diseases can be increased if pruned during the growing season are best pruned during the winter when they are dormant; pruning in late winter is generally best. Quercus spp. Oaks (to avoid oak wilt) (especially those in the red oak group) Cotoneaster, Crataegus, Cotoneasters, Hawthorns, Malus, Pyrus, and Apples & Crabapples, Pears, and Sorbus spp. Mountain Ash (to avoid fireblight) 15_Pruning_ppt.doc

Pruning Tools Hand Pruners (bypass/scissor type) Small branches up to about ½” Lopping Shears (bypass/scissor type) Branches up to about 1½” Pole Pruners (often equipped with a bypass pruner and a saw blade) Hedge Shears Pruning Saws Chain Saws Bypass Type Hand Pruner 15_Pruning_ppt.doc

Pruning Techniques Know the plant (identify the plant and understand its growth habits and natural form) and prune accordingly based on the pruning objectives. Have a plan – know your pruning objectives and have a reason for every pruning cut; pruning cuts are wounds and shouldn’t be made without good reason; pruning cuts also can’t be undone and have a lasting effect which can be positive or negative. 15_Pruning_ppt.doc

Pruning Techniques Use the proper tool in the correct manner; pruning tools should be clean, sharp (precise cuts heal more quickly than rough cuts) and in good working condition. Keep pruning cuts (wounds) small by pruning sooner rather than later. Never leave stubs, but avoid flush cuts. 15_Pruning_ppt.doc

Pruning Techniques Do not cut into the branch collar (but, again, don’t leave stubs). With a few exceptions, the best time to prune is during the dormant season; late winter/early spring just before growth begins (March/April). As a general rule, no more than one third of the living crown should be removed each year. 15_Pruning_ppt.doc

Apical Dominance When the terminal (topmost) bud is dominant, the degree of apical dominance determines the form of a plant and varies among species; strong apical dominance results in a conical form while weak apical dominance results in broader forms (upright oval and rounded forms). Vines have very strong apical dominance and relatively weak stems. Heading back to remove the terminal bud can promote branching and increased density by promoting the growth of axillary (side) buds, but will be less effective for plants that exhibit strong apical dominance. 15_Pruning_ppt.doc

Apical Dominance Terminal Bud When the terminal (topmost) bud is dominant, the degree of apical dominance determines the form of a plant and varies among species. Strong apical dominance results in a conical form while weak apical dominance results in broader forms (upright oval and rounded forms). Vines have very strong apical dominance and relatively weak stems. Heading back to remove the terminal bud can promote branching and increased density by promoting the growth of axillary (side) buds, but will be less effective for plants that exhibit strong apical dominance. 15_Pruning_ppt.doc

Apical Dominance 15_Pruning_ppt.doc

Apical Dominance 15_Pruning_ppt.doc

Apical Dominance 15_Pruning_ppt.doc

Pruning Techniques Pinching stems back to increase plant density (herbaceous plants) Heading back small branches Removing large branches Thinning Gradual renewal Rejuvenation pruning Evergreen trees & shrubs Hedges Root pruning Deadheading 15_Pruning_ppt.doc

Heading Back Small Branches Head back to an outward growing bud and cut at a 45º angle just above the bud. 15_Pruning_ppt.doc

Heading Back Small Branches 15_Pruning_ppt.doc

Heading Back Small Branches Prune back to an outward growing branch, not branches growing back into the plant. 15_Pruning_ppt.doc

Removing Large Branches 15_Pruning_ppt.doc

Removing Large Branches The ultimate goal, but remove the weight of the branch first to avoid stripping the bark. 15_Pruning_ppt.doc

Removing Large Branches Use three cuts 15_Pruning_ppt.doc

Removing Large Branches Use three cuts 15_Pruning_ppt.doc

Removing Large Branches Use three cuts 15_Pruning_ppt.doc

Removing Large Branches Branch Collar Do not cut into the branch collar Use three cuts 15_Pruning_ppt.doc

Deciduous Shrubs Selectively heading back branches to open up the crown of the plant. 15_Pruning_ppt.doc

Deciduous Shrubs Selectively heading back branches to open up the crown of the plant. 15_Pruning_ppt.doc

Deciduous Shrubs Multi-Stemmed Shrubs – Removing up to 1/3 of the stems to the ground to stimulate new growth from the base of the plant. Maintains natural form, keeps plants shorter, maintains flowering and fruiting. 15_Pruning_ppt.doc

Deciduous Shrubs Multi-Stemmed Shrubs – Removing up to 1/3 of the stems to the ground to stimulate new growth from the base of the plant. Maintains natural form, keeps plants shorter, maintains flowering and fruiting. 15_Pruning_ppt.doc

Deciduous Shrubs Multi-Stemmed Shrubs – Removing up to 1/3 of the stems to the ground to stimulate new growth from the base of the plant, maintains natural form. Keeps plants shorter, maintains flowering and fruiting. Cutting the entire plant to the ground is called rejuvenation and can be used on vigorous plants that sucker from the base. Flowering and fruiting will not occur for several years. 15_Pruning_ppt.doc

Evergreen Trees and Shrubs Candle Growth in Early Spring Yew Pines Spruce, Fir, Hemlock, Yew, Arborvitae, Juniper, & Broadleaf Evergreens 15_Pruning_ppt.doc

Hedges Plants planted in rows for screening or to define landscape spaces (hedges) may be maintained in their natural form or may be sheared for a formal effect. Shearing is higher maintenance. When sheared, being wider at the base allows for better light exposure and avoids bare stems as a result of shading. 15_Pruning_ppt.doc

Review Definition of Pruning Reasons for Pruning When to Prune (timing) Pruning Tools Rules of Pruning Apical Dominance Pruning Techniques 15_Pruning_ppt.doc

Definition of Pruning A horticultural practice involving the removal of portions of a plant to control growth, form and size, correct structural defects, improve health, vigor and structure, and enhance flowering and fruiting. 15_Pruning_ppt.doc

Reasons for Pruning To encourage proper development, natural form, and vigor. To repair damage. To direct or control growth. To encourage flowering and fruit production and to improve fruit quality. To create specialized or unique forms (e.g., topiary, espalier, bonsai). To create compact, well-branched, transplantable root systems. To remove dead/faded flowers (deadheading). 15_Pruning_ppt.doc

When to Prune (timing) Late winter (dormant season) Spring Summer Fall Most pruning is performed in late winter and early spring. 15_Pruning_ppt.doc

When to Prune Late winter/early spring (before new growth begins) – shrubs that bloom on current season’s growth; shrubs grown primarily for their foliage; most trees. Spring (just after flowering) – shrubs that bloom on last season’s growth. Summer – limited, minor pruning (e.g., removing dead wood and broken branches); trees that “bleed” sap in early spring if pruned in winter. Fall – limited, minor pruning (e.g., removing dead and broken branches). 15_Pruning_ppt.doc

Pruning Tools Hand Pruners Lopping Shears Pole Pruners Hedge Shears Pruning Saws Chain Saws 15_Pruning_ppt.doc

Rules of Pruning Know the plant (identify the plant and understand its growth habits and natural form) and prune accordingly based on the pruning objectives. Have a plan – know your pruning objectives and have a reason for every pruning cut. Pruning cuts are wounds and shouldn’t be made without good reason; pruning cuts can’t be undone and have a lasting effect which can be positive or negative. Use the proper tool in the correct manner; pruning tools should be clean, sharp (precise cuts heal more quickly than rough cuts), and in good working condition. Keep pruning cuts (wounds); prune sooner rather than later. Never leave stubs, but avoid flush cuts. Do not cut into the branch collar (but, again, don’t leave stubs). With a few exceptions, the best time to prune is during the dormant season; late winter/early spring just before growth begins (March/April). As a general rule, no more than one third of the living crown should be removed each year. 15_Pruning_ppt.doc

Pruning Techniques Pinching – pinching stems back to increase plant density (herbaceous plants) Removing Side Branches – cut just outside the branch collar, not flush with the trunk Thinning – removing individual branches to make plants more open (trees and shrubs) Heading Back – shortening branches by cutting back to an outward pointing bud (mainly shrubs) Gradual Renewal/Rejuvenation – removing entire stems near the ground to renew from the base (mainly shrubs) Hedges – choose between natural form or sheared; shearing is higher maintenance Root Pruning Deadheading 15_Pruning_ppt.doc

15_Pruning_ppt.doc

Connect with horticulture and landscaping resources. Thank you for using the Pathways through Horticulture Curriculum, provided to Minnesota teachers free-of-charge, courtesy of the Minnesota Nursery & Landscape Association and the MNLA Foundation. For more information or to inquire about other resources offered by the MNLA Foundation, please contact: MNLA Foundation Office: 651-633-4987 Email: MNLA@MNLA.biz   www.MNLAschoolhouse.org Connect with horticulture and landscaping resources. www.theLandLovers.org Your resource for careers in the green industry.   These lessons were obtained through a purchase agreement between the Minnesota Nursery and Landscape Association (MNLA) and the Pennsylvania Landscape and Nursery Association (PLNA) and have been modified by the MNLA. The Pennsylvania Landscape and Nursery Association retains all original ownership rights and all copyrights. © 2005, Pennsylvania Landscape and Nursery Association. All Rights Reserved.