Fragrant and beautiful, who doesn’t love lilacs? People with monstrously overgrown lilac shrubs, that’s who.
Right NOW is a great time to prune your spring-blooming shrubs including lilac (Syringa), Deutzia, Forsythia, bridal wreath spirea (S. prunifolia), Fothergilla, azaleas/rhododendrons, and ninebark (Physocarpus). We prune those shrubs that bloom heaviest in spring -- and all at once -- right AFTER the blooming is done and the flowers have faded. This will increase the quantity or quality of next year’s flowers. Why? Because shrubs that put on a huge spring flower display are forming next year’s flower buds … this summer. This is called “blooming on old wood” and it’s confusing the first 17 times you think about it. Once you start caring for your plants correctly and you go through the cycle a few times, it makes more sense.
There are many kinds of pruning cuts, and for lilacs (and other flowering shrubs) we focus on two:
DEAD-HEADING* is the removal of faded flowers and seeds. Allowing seeds to form takes energy away from new flower bud formation, so clip those off pronto.
HEADING BACK means to remove part of a branch to encourage new growth and/or to improve the mechanics of the shrub (increase air and light penetration, for example). Shorten leggy branches and always ALWAYS prune back to a joint where two parts of a branch come together. Do NOT leave long stubs when pruning, as these will simply die back into the plant and cause new and exciting problems.
* It is not necessary to wear tie-dye and dance like Jerry Garcia while pruning, but hey, whatever.
NOTE: If your shrub is already massively overgrown, a more severe pruning may be indicated to bring it back under control. Fortunately, lilacs are resilient shrubs and are usually forgiving of <ahem> awkward pruning. This is not true of all shrubs.
You can also radically simplify your pruning chores by hiring me to come over and either A) give you a pruning lesson on the major plants in your yard, or B) simply do a high-quality pruning job for you! Either pruning service you choose is $70/hour with a 2-hour minimum. Contact me ASAP to get your spring-blooming shrubs pruned NOW for a fabulous flower show next spring! Please get these plants pruned before the end of June.