TIPS & TRICKS

 

Pruning plants for best flowering The following pruning chart is the best time to prune plants in the landscape for best flowering. Nursery growers need to follow other rules of pruning. How to Prune Not all plants grow the same way, and should be pruned according to the particular growth habits of the plant. Some plants benefit from severe pruning, others do not. Pruning for nursery propagation Prune plants in late winter or early spring prior to bud break. Remove old, dead, broken or diseased growth. Pruning for propagation encourages lots of new spring growth for softwood cuttings. It often means giving up flowers in exchange for cuttings. The rest of this article is about pruning for best flowering. It is specifically aimed at plants in the ground in a permanent location. Pruning encourages new growth and branching. As a rule of thumb new growth occurs 4"-6" down the cane or branch, from the place where it was pruned. Be sure to leave enough cane or branch for new growth, but remove enough to keep the plant from getting too large and unmanageable. In other words, leave at least 4"-6" of the pruned branch for new growth. Prune thoroughly and remove all apical tips. The apical tip is the growing end of the branch or cane. Removing the apical tip forces new growth from the branch or cane. Slow growing plants like boxwood and barberry can be pruned lightly all over, removing the apical tips. Larger, faster growing shrubs can be pruned more severely, and many shrubs benefit from a severe pruning every 3rd or 4th year. Pruning for shape and size Consider the desired shape and size of the finished plant before pruning. Many plants have a natural growth habit. Pruning should usually promote a plant's natural growth habit, unless you are trying to create topiaries, tree-form shrubs and other ornamental shapes. Pruning should be done every year to maintain the optimal shape, size and health of your landscape plants. Newly planted shrubs can be left unpruned for several years until they are well established. Method of Thirds pruning Plants that put up canes from a central root mass are usually pruned using the "method of thirds." Viewing the plant as a whole we divide the canes into 3 groups - (1) diseased, damaged, crossed or undesirable canes, (2) old unproductive canes, (3) new productive canes. Start by removing all group (1) canes; cut them all the way to the ground with clean, sharp pruning shears. Remove canes that are crossed, or interfere with the general shape and appearance of the plant. You also want to open the center of the plant so light gets down to the canes in the middle. It's a good idea to dip the shears in a horicultural disinfectant between cuts so you don't transfer any disease to healthy canes. I use and recommend Physan 20 for this purpose. Next remove group (2) old unproductive canes to the ground. Most of this type of plant produces flowers on either new or 1-year old growth, so 2- or 3- year old growth is no longer productive and can be removed. After removing groups (1) and (2) canes you should be left with new, healthy productive canes. You can trim these up a bit, to improve the shape of the plant. At most, remove the top third of the healty canes to shape and clean up the plant in general. What has happened with this pruning? Consider a plant as a whole system. What your eyes see are the canes, foliage and flowers above ground. What you don't see is a root mass of equal or greater size below the ground, supplying water and nutrients to the plant. By pruning we help maintain a healthy balance between foliage and woody growth above ground, and roots below the ground. When the plant breaks dormancy it will explode with new growth, as the root mass pushes up large amounts of new growth. Remember that there's a symbiotic relationship between foliage and roots. Roots provide water and nutrients to the plant. Foliage provides photosyntheses to convert sunlight and nutrients into usable energy for the plant. Flowers are part of the reproductive cycle for the plant, provide lots of color and fragrance, and often attract birds, butterflys, hummingbirds and other desirable visitors to the garden. Pruning other types of woody ornamentals Prune each type of plant according to the needs of that genus and species. Some plants need only occasional pruning to shape the plant, while others beneift from more frequent pruning. Small bushy plants such as spiraea benefit from occasional severe pruning in late winter before spring growth begins. Slow growing plants like boxwood and barberry should be pruned lightly, just enough to shape the plant and encourage new growth. If in doubt, do a little research on a plant before pruning it. Best time to prune In general the best time to prune is when plants are dormant because the plant suffers less shock from pruning at that time. But that is not always the case. Plants that flower early in the spring should generally be pruned after they flower. New growth will bear flowers the following spring and should be left unpruned until after the next year's flowering cycle. The chart below shows the best time to prune plants for best flowering. Legend: * = Best time to prune x = Do not prune except to correct damage, hazards, or structural defects - = Timing is not critical

 

Plant

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Comments

Abelia

*

*

x

x

x

x

x

x

x

x

*

*

1 4

Almond, Flowering

x

x

x

x

*

*

*

x

x

x

x

x

2 4

Arborvitae

*

*

*

-

-

*

*

x

x

x

*

*

6

Aucuba

x

x

x

x

x

*

*

x

x

x

x

x

2

Azalea, Deciduous

x

x

x

x

*

*

*

x

x

x

x

x

2

Azalea, Evergreen

x

x

x

x

*

*

*

x

x

x

x

x

2 7

Barberry, Decidudous

x

x

x

x

*

*

*

x

x

x

x

x

2 4

Barberry, Evergreen

x

x

x

x

*

*

*

x

x

x

x

x

2 4

Bayberry

x

x

*

*

*

*

x

x

x

x

x

x

Beautyberry

*

*

*

x

x

x

x

x

x

x

*

*

1 7

Beautybush, Kolkwitzia

x

x

x

x

x

*

*

x

x

x

x

x

2 4

Boxwood

*

*

*

*

*

*

*

x

x

x

*

*

5

Broom (Cytisus)

x

x

x

x

x

*

*

x

x

x

x

x

2

Butterfly-bush

*

*

*

x

x

x

x

x

x

x

*

*

1

Camellia, Japanese

x

x

x

*

*

*

x

x

x

x

x

x

2

Camellia, Sasanqua

x

x

*

*

*

x

x

x

x

x

x

x

1

Chastetree (Vitex)

*

*

*

x

x

x

x

x

x

x

x

x

1

Cherrylaurel (Prunus)

*

*

*

*

*

*

*

x

x

x

*

*

5

Clethra, Summersweet

*

*

*

x

x

x

x

x

x

x

*

*

1

Cotoneaster, Deciduous

*

*

x

x

x

x

x

x

x

x

*

*

3

Cotoneaster, Evergreen

*

*

x

x

x

x

x

x

x

x

*

*

3

Crape Myrtle

*

*

*

x

x

x

-

-

-

x

x

x

1 8

Daphne, Fragrant or Winter

x

x

x

*

*

*

*

x

x

x

x

x

2

Deutzia

x

x

x

x

x

*

*

x

x

x

x

x

2 4

Dogwood, Redtwig

*

*

*

x

x

x

x

x

x

x

*

*

1 4

Eleagnus, Thorny

*

*

*

*

*

*

*

x

x

x

*

*

Euonymus, Deciduous

*

*

*

x

x

x

x

x

x

x

*

*

Euonymus, Evergreen

*

*

*

*

*

*

*

x

x

x

*

*

5

Forsythia

x

x

x

*

*

*

*

x

x

x

x

x

2 4

Fothergilla

x

x

x

x

*

*

*

x

x

x

x

x

2

Gardenia

*

*

x

x

x

x

x

x

x

x

*

*

1

Harry Lauder's Walking Stick

x

x

x

x

*

*

*

x

x

x

x

x

2

Hibiscus, Rose of Sharon, Althea

*

*

*

x

x

x

x

x

x

x

*

*

1

Holly, Deciduous

*

*

x

x

x

x

x

x

x

x

x

*

1

Holly, Evergreen

x

x

x

x

x

*

*

x

x

x

x

x

2 5

Honeysuckle

x

x

x

x

*

*

*

x

x

x

x

x

2 4 5

Hydrangea, Spring blooming

x

x

x

x

x

*

*

x

x

x

x

x

2

Hydrangea, Summer blooming

*

*

*

x

x

x

x

x

x

x

*

*

1

Hypericum, St. Johnswort

*

*

*

x

x

x

x

x

x

x

x

x

1

Indian Hawthorn (Raphiolepis)

x

x

x

x

*

*

*

x

x

x

x

x

2

Jasmine, Winter

x

x

x

*

*

*

*

x

x

x

x

x

2

Juniper

*

*

*

-

-

-

-

x

x

x

*

*

6

Kerria (Globeflower)

x

x

x

x

x

*

*

x

x

x

x

x

2 4

Leucothoe

x

x

x

x

x

*

*

x

x

x

x

x

4

Lilac

x

x

x

x

x

*

*

x

x

x

x

x

2 4

Mahonia, Oregon Grapeholly

x

x

x

x

*

*

*

x

x

x

x

x

2 4

Mockorange

x

x

x

x

x

*

*

x

x

x

x

x

2 4

Mountain laurel (Kalmia)

x

x

x

x

x

*

*

x

x

x

x

x

2

Nandina

*

*

*

x

x

x

x

x

x

x

x

x

1 4

Osmanthus Holly

*

*

-

-

-

*

x

x

x

x

*

*

1 5

Pearlbush

x

x

x

x

x

*

*

x

x

x

x

x

2

Photinia

*

*

-

-

*

*

*

x

x

x

*

*

5

Pieris

x

x

x

x

*

*

*

x

x

x

x

x

2

Pine, Mugo

*

x

x

*

*

*

x

x

x

x

x

*

9

Pittosporum

x

*

*

*

*

x

x

x

x

x

x

x

Potentilla

*

*

*

x

x

x

x

x

x

*

*

*

1 4

Privet, Deciduous (Ligustrum)

*

*

*

*

*

*

*

x

x

x

*

*

5

Privet, Evergreen (Ligustrum)

*

*

*

*

*

*

*

x

x

x

*

*

5

Pyracantha

x

x

x

x

x

*

*

x

x

x

x

x

2 3

Quince

x

x

x

*

*

*

*

x

x

x

x

x

2 4

Rododendron

x

x

x

x

x

*

*

x

x

x

x

x

2

Rose

x

*

*

x

x

x

*

*

x

x

x

x

1 3 4

Serviceberry

x

x

x

*

*

*

x

x

x

x

x

x

Smoke Tree

*

*

x

x

x

x

x

x

x

x

*

*

1

Spirea, Spring-blooming

x

x

x

x

*

*

x

x

x

x

x

x

2

Spirea, Summer-blooming

*

*

x

x

x

x

x

x

x

x

x

x

1

Sumac

*

*

*

x

x

x

x

*

*

*

*

*

1 4

Sweetshrub, Carolina Allspice

x

x

x

x

x

x

*

*

x

x

x

x

1

Viburnum, Deciduous

x

x

x

x

*

*

*

x

x

x

x

x

2 4

Viburnum, Evergreen

x

x

x

x

*

*

x

x

x

x

x

x

2

Weigela

x

x

x

x

*

*

*

x

x

x

x

x

2 4

Willow, Pussy

x

x

x

*

*

*

*

x

x

x

x

x

2

Witchhazel

x

x

x

*

*

*

*

x

x

x

x

x

2

Yew

*

*

*

-

*

*

*

x

x

x

*

*

5

Comments
1. Flowers are produced on new (current season) wood
2. Flowers are produced on wood from past season, pruning while dormant will reduce flowers
3. Make pruning cuts well below diseased wood (fire blight) - disinfect shears between cuts
4. Remove old stems to ground yearly to renew
5. Midseason shear if a formal hedge is desired
6. Do not cut into old wood that has no leaves or needles
7. Spring/summer prune to remove azalia caterpillars and galls
8. Fall/early winter pruning can reduce winter hardiness
9. Snap candles (new growth) in half when needles are 1/2 to 2/3 their normal mature length

Exceptions
1. Timing varies across USDA climate zones
2. Prune anytime to correct vandalism and hazards created by equipment or weather
3. Hedges maintained formally (tight shapes) require more pruning than hedges maintained informally (in their natural form)