S. vulgaris thrives in mild climates of zones 3-7 and its flowers can be enjoyed in late spring to early summer. A drawback of this popular shrub is that it offers little ornamental qualities past its blooming season, and in the summer its foliage is prone to powdery mildew as well as insect pests like borers, scalers and caterpillars, so it may require the gardener to look into some IPM. The common lilac is native to Europe and was introduced to North America in the 1600s, therefore it is invasive to certain regions of the US, particularly in the northeast. Ways to prevent its invasive nature is to diligently remove root suckers and to routinely prune flowers right before they set to seed. Regardless of these negative characteristics, S. vulgaris is highly sought after and commercially propagated across the northern United States, especially due to its flowers and relative ease to care for.
Most commercially produced lilacs are propagated from micropropagation, however they can also be propagated through seeds or grafting techniques, as well as by cuttings. Propagation by seed is usually paired with grafting, as well as rootstock production. Seeds require outdoor stratification, or can be stratified indoors for 40-60 days at around 4 degrees Celsius. A problem posed by seeds is that they will not yield true cultivars. Commercially, propagation by grafting is uncommon since it is expensive, tedious (because of rootstock suckering), and hit-or-miss in regard to growth renewal (Hartmann and Kester). Cuttings can be used to propagate S. vulgaris, however it can be difficult (Smith). The timeframe that the cutting is taken is critical, where it should be collected in the early spring after a rush of fresh shoot growth. Its succulent leaves make wilting a common problem, however the timeframe for success can be widened with a good misting/fogging system to avoid excessive water loss from evaporation within the plant. Subjecting the mother plant to etioliation has also shown to increase the timeframe for successful rooting (Fordham). Commercial propagators can efficiently utilize micropropagation methods, as well as some cutting methods, however due to lack of proper equipment a home grower should stick to propagation by cuttings, grafting or seed. Cuttings may be difficult for the home propagator as well since proper IBA application is necessary.
1. Wait until the early spring after the shrub has experienced its first flush of newly grown shoots.
2. Make sure the shrub is free of disease and has been acclimated to proper environmental conditions.
3. Select a freshly grown lateral shoot as the cutting. Take a terminal cutting at about 10-15 cm with a sharp, sanitized edge. Make the cut slightly below a node, and remove the bottom leaves, leaving two or three leaves at the top. To maximize turgor, take the cutting in the early morning and temporarily store it in an opaque container, free from sunlight exposure.
4. Prepare the media, ideally a washed sandy soil. The media should have good drainage characteristics.
5. Dip the cutting in a talc based IBA. 1500-3000 ppm Hormodin works well for this and can be purchased at your local garden supplier.
6. Place the cutting in the soil about 4 cm deep. Compact the area around the base to ensure stability.
7. Water in the media and allow for sufficient drainage.
8. Once the cutting is in place, use direct contact techniques with a polyethylene film. Wrap in in the film to minimize water loss from evaporation. Misting and fogging systems work well for this too, if applicable. Remove the film on humid, foggy days and routinely check for pests and dryness.
9. The cutting should root in about 7 weeks. Once rooting takes place, transplant the new plant to a new potting media which can be bought from your local garden supplier. Maintain the polyethylene cover, removing it on cloudy humid days to harden it off. When 3-5 successive cloudy days persist where cover is not necessary, your new lilac will be ready to be added to your landscape.
Propagating lilacs from cuttings is difficult, but very possible if timing is strictly considered. The relatively few supplies it takes to produce a successful cutting make it a fun experiment for a home gardener and a successful finished product will yield a plant that the propagator can look at in their landscape and be proud of. The common lilac is a favorite in many different landscapes, and its sweet smelling cut flowers are an added bonus to a plant that is enjoyed both indoors and out, yielding fruits of labor that persist for multiple years.
Fordham, Alfred J. “Propagation and Care of Lilacs.” Vol 19. 1959. Rpt. in Arnold Arboretum of Harvard University. Web. 08 Oct 2014.
Hartmann, Hudson T., Dale E. Kester, Fred T. Davies, and Rovert L. Geneve. Hartmann & Kester’s Plant Propagation: Principles and Practices. 8th ed. Boston: Prentice Hall, 2011. 820. Print.
Smith, Curtis W. Ph.D. “Lilac Propagation.” New Mexico State University. NMSU Cooperative Extension Service. 14 May 2005. Web. 08 Oct 2014.
“Syringa vulgaris.” Missouri Botanical Garden. N.p.. Web. 8 Oct 2014.