Lilac tree – Pruning, Winter Care and Fertilizing

Lilac Japanese tree, including reticulata and pekingensis.

These trees should be pruned in early spring, before the sap starts to flow (March). This will remove some spring flowers. Pruning can also be done in summer, after the leaves are full size. This plant should not be sheared.

The time to make a long lasting effect on the form and structure of the plant is when the tree is young. Crossing or crowded branches, suckers and water sprouts should be removed. Low branches should also be removed, if desired, when the tree is young. This is best done by removing one or two branches a year, over a period of a few years, until the needed clearance is obtained. As the tree gets older, pruning every three to five years will keep the tree in good general shape. Water sprouts and suckers, however, should be removed each year.

By fertilizing young trees you can increase both the size and the amount of flowers on the plant. Granular, liquid or stake type fertilizers can be used. Granular types should be worked into the soil around the plant at a rate of 2 pounds or 2 pints per 100 square feet of planting bed. An alternative way is to drill or punch 6″ deep holes at the drip line of the plant. Poured into these holes should be a total of 1/4 pound of fertilizer per foot of height or spread of the shrub (divided up and poured evenly between all of the holes). These holes should not be filled with more than 1/3 of the fertilizer and then they should be top filled with soil. This method of fertilization should only be done once a year, and is best done in late fall after leaf drop, or in early spring before bud break.

Liquid fertilizers (such as Miracle Gro) are mixed with water and applied the same as you would water the plant (see product for specific details). This should be done three or four times per year starting in late April and ending in mid July. Stake type fertilizers can be used following the directions on the package. With any of the above techniques a balanced mix should be used, 20-20-20 or 20-30-20 or 18-24-16. Organic fertilizers, like manure, can also be used with good results. The material should be worked into open soil at a rate of one bushel per one 6′ shrub or 100 sq. ft. of bed area.

These trees need little winter care but, should be checked now and then for rabbit or other damage. If rabbit damage is found you can protect the plant with a fence formed with hardware cloth (looks like chicken wire but, with small square holes). The plant is tied in if necessary, then a section of hardware cloth is put around the outside. The base of the cloth is buried in the soil or mulch. This protection should be installed in late November and removed in mid April.