How to Prune Syringa Vulgaris

Syringa vulgaris, or lilac, must be trimmed in the spring.

Syringa vulgaris, more commonly known as lilac, is an intensely fragrant flower loved by many for both its scent and attractive bloom. It is also a flower that needs careful pruning, which is often incorrectly done. Due to the nature of its blooming, pruning a lilac bush at the wrong time of year can result in a bud-less bush come springtime. Prune your lilacs in the spring, after the shrub has finished blooming.

Things You'll Need

• Garden shears
• Garden bag
• Gloves
• Rake (optional)

Instructions

1. Prune your shrubs in the spring, just after the lilacs have finished blooming. Wearing gloves prevents scratches on the hands and improve grip on the shears.

2. Remove approximately one-third of a bush's finished blooms, cutting the branches back about one-third of the way to the trunk. Use the garden shears to make the cuts.

3. Trim any branches growing near ground level from the bush's main trunk.

4. Place all the clippings in a garden bag to keep the lawn or garden clear.

Tips & Warnings

• Lilacs bloom only on old branches from previous seasons, meaning that if every bud on the bush were pruned there would be no blooms the next spring. For this reason, gardeners almost never prune the entire lilac shrub at once.

• It takes approximately three years for a lilac bud to mature, so trimming one-third of a lilac's blooms each spring puts them on a three-year cycle. By the end of the third year of regular pruning, the first year's pruned buds should begin to flower.

• Keep the center of the bush clear to allow good airflow and adequate sunlight to its inner depths.

• For best results, trim lilac bushes every spring, and gradually shape them to your liking.

• Failure to prune lilac bushes regularly could mean that the bush could grow to as high as 30 feet, depending on the variety, making it very difficult to prune.

• Pruning in the fall is unadvised, but if a lilac bush is very overgrown it may be necessary to trim away more than one-third of a bush's buds. Remember, though, that it won't bloom for a few years.

• Prune a lilac bush after it has reached a height of 6 to 8 feet tall.

References

• Gardening Know How: Pruning Lilac Bushes
• Country Living magazine: Pruning Lilac Bushes
• Gardener's Network: How to Prune Lilacs