Early spring is a good time to prune your spring and summer-flowering shrubs. Pruning will influence your shrub’s shape, size and pest problems, and most importantly it will encourage flowering.
Spring-flowering shrubs bloom on one-year-old wood (i.e. twigs that grew new the previous summer). Examples of spring-flowering shrubs include forsythia, Nanking cherry, quince, bridalwreath and Vanhoutte spirea, viburnum, beautybush, lilac, honeysuckle, peashrub, deutzia, and weigela.
Summer-flowering shrubs bloom on new wood that grew earlier in the growing season. Examples of summer-flowering shrubs include butterfly bush, blue mist spirea, Bumald and Japanese spirea, Hancock coralberry, mockorange, potentilla, Annabelle and Peegee hydrangea, shrub althea or rose of Sharon, snowberry, and St. John’s wort.
To prune your flowering shrubs, remove one-third of the oldest wood by cutting it back to the ground. This method of pruning is known as thinning. Annual thinning will encourage new growth from the base of the plant, which will ensure good dispersal of blooms from the top of the shrub to bottom.