February 2018

What shrubs to prune when

(C) Fotolia

(C) Fotolia

Before you get too crazy with the pruning chores this spring and summer, know which shrub you are snipping and why. On June 3, I offer shrub pruning tips on Indianapolis’ Fox 59.

Pruning is selective, done usually to remove dead or damaged branches, errant growth or to keep limbs from blocking walkways, to improve natural aesthetics.

The best way to reduce pruning duties is to plan for the mature size of plants and to allow them to grow in their natural form.

Shrubs that flower in spring, such as forsythia, lilacs and weigela should be pruned within four weeks after they bloom. That’s because these shrubs develop their flower buds in late summer. Pruning these plants in fall or spring removes this year’s flowers.

Purdue University has a good publication on pruning ornamental shrubs. Here’s a sampler of what shrubs to prune when.

Prune these shrub within a month to six weeks after they bloom:

  • Shadblow, Juneberry, serviceberry (Amelanchier)
  • All-spice, sweetshrub (Calycanthus)
  • Redbud (Cercis)
  • Flowering quince (Chaenomeles)
  • Fringetree (Chionanthus)
  • Flowering dogwood (Cornus florida)
  • Korean dogwood (Cornus kousa)
  • Cornelian cherry (Cornus mas)
  • Smoketree (Cotinus coggygria)
  • Cotoneaster (Cotoneaster)
  • Hawthorn (Crataegus)
  • Deutzia (Deutzia)
  • Forsythia (Forsythia)
  • Big-leaf hydrangea (Hydrangea macrophylla)
  • Oak leaf hydrangea (Hydrangea queercifolia)
  • Spicebush (Lindera)
  • Several magnolias (Magnolia grandiflora, M. stellata)
  • Crabapple (Malus)
  • Mock orange (Philadelphus)
  • Flowering cherry, flowering plum (Prunus)
  • Rhododendron, azalea (Rhododendron)
  • Black jetbead (Rhodotypos scandens)
  • Rose (Rosa)
  • Spirea (Spiraea thunbergii and S. x vanhouttei)
  • Lilac (Syringa)
  • Viburnum (Viburnum)
  • Weigela (Weigela)
  • Wisteria (Wisteria)

Prune these shrubs before new spring growth begins:

  • Butterfly bush (Buddleja davidii)
  • Beautyberry (Callicarpa)
  • Blue-mist spirea (Caryopteris)
  • Rose of Sharon (Hibiscus syriacus)
  • Hydrangeas: Smooth leaf (Hydrangea arborescens) and Peegee or panicle (Hydrangea paniculata)
  • St. John’s Wort, (Hypericum)
  • Golden raintree (Koelreuteria paniculata)
  • Sweet bay magnolia (Magnolia virginiana)
  • Sumac (Rhus)
  • Hybrid tea roses (Rosa)
  • Snow- or coralberry (Symphoncarpos)

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