Notes on pruning Amelanchier, Buddleia, Cornus, Deutzia, Erica, Hibiscus, Lavendula, Mahonia, Philadelphus, Potentilla, Syringa (by genus), Butterfly Bush, Rose of Sharon, Mock Orange, Common Lilac (by common name). Last edited Friday, November 11, 2005 02:21 PM Links at bottom. Every year in spring we have a large plant sale in the back yard of my house where I have to be anyway; potting, potting and repotting. This link takes you where I can tell what we sell and when we sell it.
Amelanchier canadensis is the nativive Shadbush, Shad or Shadblow and can easily be trained to tree form by reducing the side branches early in Spring.
Buddleia davidii (Butterfly Bush) In early spring I initially reduce the shrub by 1/2. Later as new growth buds become evident I reduce even further, sometimes back to 3 or 4 inches. Fertilize well with manure after each pruning. I find that the cultivar 'Black Knight' doesn't do well in my garden whereas 'Nanho Purple' does exceptionally well.
Cornus alba The red or yellow stems of these dogwoods, which provide winter interest are shortened every spring (F1) almost to ground level. Feed in late spring and several feet of growth will result each year.
Deutzia Cut back flowered shoots as soon as flowers fade.
Erica Prune each spring. Avoid cutting into old wood.
Forsythia older stems are cut after flowering and younger stems trained to replace them. Flowers are produced on last years growth.
Hibiscus syriacus For a hedge cut Rose of Sharon back in Spring. Otherwise remove dead or diseased branches. Flowers are produced on new growth.
Hydrangea H. macrophylla flowering stems are cut back in Spring to within 2 inches of the old wood and H. paniculata cut back to 4 buds in spring.
Lavandula Prune Lavender in Spring cutting off previous years flowers and the young growth to near its base. Replacement cuttings should be taken for the time that you no longer can improve the looks of the plant.
Mahonia Pruning on Oregon Grape is best done in Spring.
Philadelphus Many Mock Orange plants perform well without ever being pruned. It is sure however that it should have adequate feeding every spring.
Potentilla Prune back by 1/3 in Spring (Pruning article).
Syringa vulgaris (Common Lilac) Prune the stem with the largest diameter (one each year) to the ground each year before leaves emerge. Some varieties benefit from the removal of seed pods after flowering. Without seed pod removal you may have less tip growth.