Dan West Garden Center

October 2006 Newsletter

As promised, this month's topic is pruning.  First, let's define pruning, the different types of pruning and some of the terms associated with pruning, and then we'll talk plant specifics.

Pruning: (From Microsoft Encarta World English Dictionary)

 "To cut branches away from a plant to encourage fuller growth."  This is "selective pruning".  We use selective pruning on flowering shrubs like forsythia and hydrangeas, some types of azaleas, nandinas, crape myrtles, butterfly bushes and roses.  For the most part, selective pruning improves the health and vigor of a plant and it's overall appearance.

"To reduce something by removing unwanted material."  This is "shearing".  When we trim boxwoods or shape any plant to retain a desired size, we do so more for aesthetic reasons than for the health of the plant.  In some cases, this causes additional problems.  The more you shear a plant, the thicker foliage on the outside of the plant shades the internal leaves and often they fall off.  It also reduces air flow and creates an environment for insects and diseases to flourish. Case in point: Golden euonymus.  Nasty plant.  It gets euonymus scale and powdery mildew if you continually shear it.  This is also "hard pruning" to reduce the overall size of a plant.  Some plants will recover fine from this if done at the proper time, some plants will not re-sprout on 2 year old wood, leaving bare stubs. If you need to hard prune a shrub, it's probably the wrong shrub there in the first place.  Consider removing it and replacing it with a plant better suited for the area.

"To remove something unnecessary."  This is deadheading old flowers, removing dead or damaged wood, or removing flowers on plants that we just don't want to bloom such as caladiums or hosta flower spikes for those of us that like the foliage much more than the flowers.

Let's start at the ground and work our way up through the garden as we discuss the proper way to prune.

Groundcovers: Vining groundcovers (ivy, Vinca minor/major, Asiatic jasmine, creeping Euonymus varieties, etc.) are easily pruned with a mower set high.  You can also use a string trimmer, but you usually end up wrapping vines around the trimmer head and teaching the neighbor's kid new vocabulary words.  The best time to prune these groundcovers is early to mid March and not after July 1.  Clumping groundcovers, such as liriope (monkeygrass), mondo and acorus (sweet flag), should be trimmed back to 1" in January also with a mower or string trimmer. (Note: There is a radical splinter group of extremist gardeners that believe it's best to cut liriope with scissors to avoid ragged edges.  These people hide among us masquerading as normal gardeners.  I'm not sure what their ultimate goal is, not much is known about them, but you need to know they are out there...so beware!  Personally, I think they're Martha Stewart sleeper cells.)

Perennials/Annuals: This one's not hard.  If it's leggy, cut it back.  If it's yellow or dead, remove it.  If the flower is spent, cut it off (unless you want it to go to seed).  Ornamental grasses should be cut back to 2"-3" in height in January.

Azaleas:  Immediately after spring bloom and never after July 1.  Most new varieties need no pruning, but some of the Glen Dale azaleas should be pruned each year.  These grow long shoots that generally just retain foliage around the flower buds during the winter.  After they bloom, cut 25% of these shoots at various heights throughout the plant.  This will thicken up the plant and increase your flowers for next year.  Spring flowering deciduous azaleas should be pruned the same way (by staggering the heights of the stems) but I'd cut more of them (50% or more).

"Excuse me!  When do you prune the Encore azaleas?"

The same rules apply for the Encores.  However, they aren't large growing azaleas so little pruning should be necessary.  If they've become thin, I'm more concerned about where they are planted.  Like all azaleas, they need good drainage, but they perform better when given a little sun.

Broadleaf evergreens: This group includes most hollies, boxwoods, Cleyera, Photinia, Indian hawthorn, Gardenias, some E uonymus, Ligustrum and any other plant that is not a needled evergreen and holds it's foliage year round.  "Shearing", to maintain the shape (cube, globe, etc), or selective pruning can be done from mid March until July 1.  Pruning before March exposes the stems to desiccation from wind and quite often we have very warm temperatures in the winter which may force new growth that gets zapped by late freezes in early April.  Pruning after July 1 forces new growth that may not harden off before winter and can be desiccated by winter winds.  Here are a few specifics you should know...                                                     

Hollies:  Only females have berries, so by pruning into last year's wood, you cut off berries.  If you absolutely must cut a holly back severely, don't remove all the leaves.  Leave a few branches alone until the plant has re-sprouted, then cut back the remaining limbs. 

Boxwoods: Once overgrown, boxwoods are difficult to reduce in size.  Don't let them get out of hand, shear them frequently to maintain their size or leave them alone and let them grow large, open and airy, the way they normally grow.

Cleyeras:  Don't shear well at all.  To thicken them, reach to the inside and cut several upright stems at different heights.

Photinia (redtips):  Make one cut...ground level with a chainsaw.  I'M NOT KIDDING! This has become a very high maintenance plant.  The more it is sheared, the more likely it is to get a leaf disease that blackens the foliage and eventually defoliates it and kills the plant.  If you must have one, avoid planting it against houses or fences that limit air flow and never, ever shear it as a hedge.  They get 25' tall.  Why would you plant something that gets 25' tall if you only want a 6' hedge?  Plant something that only gets 6' tall, it's a lot less work.

Indian hawthorn (Rhaphiolepis):  This is another plant that doesn't shear well.  It looks its best when left alone.

Gardenias:  If necessary, March pruning is best, but unless it's leggy (too little sun?) I wouldn't prune it at all.

Golden/Silver/Boxleaf Euonymus (Euonymus mostuglyii):  Obviously not my favorite plant.  They are prone to leaf diseases and scale.  This plant should not be used as a foundation planting.  The best place for this plant (if not in a pile on the curb) is in full sun away from anything that blocks air flow and it should never be sheared.

Nandinas, Mahonias:  Prune these in late March.  Each year prune about 1/3 of the canes at varying heights.

Spring flowering shrubs:  This group includes Forsythia, quince, Kerria, bridal wreath Spiraeas or any deciduous shrub that blooms in early spring.  Trim these immediately after bloom.

Summer flowering shrubs:  Rose of Sharon (Althea), Vitex and crape myrtles or any deciduous shrub that blooms in the summer should be pruned from January to March.  Crape myrtles are often trimmed incorrectly.  We call it "crape murder" when a tall crape is cut back each year to the same height causing unsightly, gnarled trunks.   Crapes don't need to be pruned at all.  If you leave them alone, they twig up and produce an abundance of small flower heads.  If you must trim them, the dwarfs (6' and under) can be cut back to the ground each March and they will produce long arching stems with large flower heads.  The taller (tree form) crapes should have all the side branching removed, just leaving the main trunks as tall as possible.  They also will produce long arching branches with huge flower heads that break in the summer rains.  Hydrangeas (mopheads and serratas) should be pruned as the flower color fades (but not after August 1), by removing a few of the oldest canes, but pruning is seldom necessary.  Paniculata and Annabelle hydrangeas can be pruned in late winter.

Trees:  After first frost through December is a good time to prune trees.  Dead or damaged wood can be removed at any time.  There is never a reason to top a tree and usually no reason to thin one.  Trees are well designed balanced organisms.  There is enough top to support the roots and enough roots to support the top.  Changing the ratio of one to the other is usually not wise. 

Sorry, not time for questions today.  If you have specific pruning questions, email me at questions@danwestonline.com.

Class dismissed.

DAN WEST GARDEN CENTERS

4763 POPLAR            12061 HWY 64

MEMPHIS, TN 38117    EADS, TN 38028

901-767-6743            901-867-2283

KENNETH MABRY - MANAGER          JIM CROWDER - MANAGER