Dwarf Korean lilac, known botanically as the Syringa meyerii species, has several cultivars that grow as large, mounding shrubs that spread 4 to 6 feet and grow the same in height. Though naturally a bush form, they are often pruned into a single trunk and staked when young to be used as specimen ornamentals in the landscape.
Measure the length of your lilac trunk from the soil line to just under the canopy. Add at least 6 inches to that measurement for the portion of the stake that goes into the soil. Acquire or cut a sturdy timber or metal stake to the desired length.
Slide the stake alongside the trunk so that they nearly touch and run parallel to one another. Drive the stake into the soil until secure and standing upright, at least 6 inches.
Tie the lilac trunk to the stake at the top just under the canopy line, at the middle and roughly 1 foot above the soil. Use soft, flexible garden tines that will not dig into the lilac bark or girdle the trunk over time.