Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 1 Pruning Woody Plants

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 2 Maintenance of Woody Plants Pruning – Formative, maintenance and renewal Mulching Deadheading Watering Weeding Staking Feeding

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 3 Pruning Woody Plants Why Prune???? To make sure plants don’t get too big To remove dead, dying, damaged or diseased wood. To train or shape e.g. espaliers, topiary, hedges etc. To maintain or improve flowering and fruiting To encourage fresh re-growth

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 4 Pruning Responses Pruning reduces the size of the aerial portion of the plant in relation to the root system. The undisturbed root system therefore serves fewer shoots and buds. Uptake of water and nutrients by the remaining shoots and buds therefore increases and a flush of growth (re- growth) occurs.

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 5 Water Sprouts/Shoots

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 6 Pruning Responses Pruning generally stimulates re-growth near the cut especially in vertical limbs that have been pruned Re-growth on limbs having a 45 to 60 degree angle from the vertical will develop further away from the cut

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 7 Pruning Responses Pruning also may indirectly stimulate growth of lateral shoots by allowing more light to penetrate the canopy of the plant Pruning a young plant will stimulate vigorous shoot growth but can delay the development of flowers and fruit The length of any delay depends on the species pruned and the severity of the pruning

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 8 Pruning Cuts Above a bud in the case of small branches Should always be cleanly done Well below infected material e.g. bacterial canker Aim to minimise the surface area Always avoid tearing Don’t apply wound dressing

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 9 Types of Pruning Cuts There are two basic types of pruning cuts Heading – removal of a part of a shoot or limb Thinning – removal of the entire shoot or limb Each results in a different growth response and has its own specific uses

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 10 Thinning Removes an entire shoot or limb to its point of origin from the main branch or lateral Some shoot tips are left undistributed, so apical dominance is maintained

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 11 Thinning New growth occurs at the undisturbed shoot tips while lateral bud development and re-growth is suppressed Thinning is the least invigorating type of pruning cut and provides a more natural growth form

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 12 Thinning

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 13 Heading By removing apical dominance, heading stimulates re-growth near the cut It is the most invigorating type of pruning cut, resulting in thick compact growth and a loss of natural form e.g. a formally pruned hedge Other types of heading are topping, pollarding and clipping

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 14 Heading

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 15 Which is Heading and Which is Thinning???

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 16 Wound Dressing Traditionally bitumastic emulsions used -Drying, movement of woody tissue and water build up all cause micro-fractures to seal -These cracks are the ideal place for fungal or bacterial spores to germinate Humid, sheltered, next to a food source -May actually increase chances of decay Innoculants such as Trichoderma viridae can reduce incidence of disease

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 17 Angled or Straight Cuts All cuts should aim to minimize size of wound Angled cuts leave an oval scar that may increase chances of disease entry Angled cuts may be useful however above alternately arranged buds, especially where buds are large Angled cuts must never fall behind the node itself

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 18 Angled or Straight Cuts

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 19

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 20 Timing of Pruning May be crucial in certain species Variable. Depends upon: Growth pattern Effect desired Tolerance of subject May need to be done more than once a year (i.e. in stages) May only need doing every few years

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 21 Timing of Pruning Avoid heavy pruning during the late summer and autumn as vigorous re- growth may occur making the plants more susceptible to cold injury Peach and almond trees for example, should not be pruned from October until January

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 22 Hard or Light Pruning Hard Pruning –Promotes rapid, vigorous re-growth in some specimens this is the best form of management –May be undesirable in the case of some vigorous specimens – Re-growth greater than existing growth (space considerations) –May promote suckering or epicormic growth

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 23 Hard or Light Pruning Light Pruning –Suits specimens intolerant of hard pruning e.g. Lavandula as it does not re-sprout very successfully –May also be suitable to prevent excessive shock response –As a rule of thumb: Prune weak growth hard and strong growth lightly if unsure of the plant’s needs

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 24 Timing of Pruning Many woody ornamentals are pruned according to their date of flowering –E.g. spring flowering plants such as forsythia are normally pruned after they bloom –Prune spring flowering shrubs during the dormant season will remove flower buds formed the previous autumn –Summer flowering plants are generally pruned during the dormant winter season

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 25 Bleeding Some plants bleed heavily after pruning Bleeding is unsightly but not usually harmful Trees prone to bleeding should be pruned in the late spring or early summer when leaves are on the tree as this reduces the amount of bleeding and allows rapid healing Plants that bleed readily include Salix, Betula, Acer, Fagus and Cornus

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 26 Aftercare Shrubs that have been pruned often need considerable amounts of soil borne nutrients to resume normal growth Application of a topdressing of fertilizer is essential Well rotted organic matter – applied as a mulch – can further enhance the soil fertility and promote growth

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 27 Scaffold Establishment for a Freestanding Tree Scaffold branches of trees should have a proper vertical and radial spacing on the trunk in order to allow a balanced growth pattern

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 28 Training Growth of lower buds or shoots can be modified by training Upright stems often suppress the development of lower side shoots Training stems horizontally can greatly increase both the growth rate and development of flower/fruit carried Stems must be tied in when young and pliable

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 29 Formative Pruning Aims to establish a framework of well formed and well placed branches (often referred to as a ‘scaffold’) Amount needed depends upon –Type of plant concerned –Quality of initial plant –The growth stage –Evergreen shrubs generally need less formative work

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 30 Root Pruning May be needed when vigour of a plant needs controlling –Bonsai, pot grown trees or shrubs etc May be an essential part of the prior preparation for lifting root-balled shrubs or trees –Trenching and backfilling May be done on bare rooted stock immediately prior to replanting

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 31 Renovation Old unmanaged specimens can be renovated through pruning Check tolerance to hard pruning before commencing Usually best practiced over a 2-3 year cycle Not worth attempting on badly diseased specimens

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 32 Renovation Deciduous shrubs should be renovated in the dormant (winter) period Delay work on evergreens until growth commences (March/April) Certain tolerant species can be coppiced –Cut back to a stump or stool near ground level Always feed and fertilize well in the following season Undertake formative pruning as a follow up

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 33 Choose your weapon There are many different types of pruning tools They have specific purposes Always choose the right tool for the job and…… ….Never try to work beyond the capacity of the tool whilst in use. It will make the job harder!

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 34 Get a Grip Hold secateurs properly – i.e. comfortably in the hand Make sure the anvil is positioned on the part to be removed Cutting should be in one easy motion….. ….if it ‘squeaks to a stop’ then use a bigger or more appropriate tool!

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 35 Make a Plan! Always ask yourself: What plant species is it? What are its pruning requirements? What effect will pruning have on its growth? Do I have the right tool(s) for the job? What are my objectives in undertaking this task?

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 36 In Conclusion Always look and think twice before cutting if unsure. Once you make a cut there is no going back!

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 37 A Final Word Always remember the D’s when you prune Always remove them when you prune any shrub: Dead Dying Diseased Deformed Displaced

Tuesday 20th April 2010RHS Level 2 Certificate in Horticulture 38 Sources of Information Brackell, C. and Joyce, D. (1996) The Royal Horticultural Society, Pruning & Training: A fully illustrated plant by plant Manual. Dorling Kindersley, London. Davis, B. (1995) The Confident Gardener: The key to successful gardening techniques. Penguin, London.