The herb Ruta graveolens, commonly known as rue, is a distinctive perennial plant valued for its strong, pungent scent and attractive blue-green foliage. While the plant can be grown from seed, vegetative propagation using stem cuttings is the most reliable and efficient way to create new, genetically identical plants. This technique bypasses the variability and slower growth associated with seedlings.
Optimal Timing and Selection of Cuttings
The best time for taking cuttings is during the plant’s active growth phase. Late spring to early summer is ideal for softwood cuttings. Alternatively, late summer is suitable for semi-hardwood cuttings taken from new growth that has just begun to firm up. This timing ensures the cutting has sufficient metabolic activity to form roots.
The chosen stem must be healthy, straight, and free of disease or pest damage. Look for new growth that is flexible but snaps when bent, indicating the correct semi-soft texture. Sterilize your pruning shears or knife with rubbing alcohol before making cuts to prevent pathogen transmission.
Step-by-Step Procedure for Taking Cuttings
Cut a section approximately four to six inches long from the identified stem. Make the cut cleanly and diagonally just beneath a leaf node, the slightly swollen point where a leaf attaches. This area naturally contains a higher concentration of growth-regulating auxins, which are necessary for root initiation.
Strip away all leaves from the lower half to two-thirds of the cutting, leaving only one or two sets at the top. Removing this foliage reduces moisture loss through transpiration while the cutting develops roots. Before planting, dip the cut end and the lowest node into a rooting hormone powder or gel.
Wear gloves and long sleeves when handling rue. The plant contains furocoumarins, which can cause phytophotodermatitis—a severe rash, blistering, and hyperpigmentation if sap contacts skin and is exposed to sunlight.
Prepare the rooting medium using a sterile, well-draining mix, such as peat moss and perlite or coarse sand, in a small pot. Use a pencil to create a hole in the medium, insert the cutting, and gently firm the mix around the base to eliminate air pockets.
Encouraging Root Growth and Establishment
The environment must be controlled to encourage root development. Place the pot in a location that receives bright light but is shielded from direct, intense sunlight, which can quickly scorch the delicate cutting. The ideal temperature for rooting is warm and consistent, generally between 65 and 75 degrees Fahrenheit.
To maintain the high humidity levels required, cover the pot with a clear plastic bag or place it under a humidity dome. This mini-greenhouse effect traps moisture, reducing the stress on the cutting’s remaining leaves. Ensure the rooting medium stays consistently moist, but never soggy, as excessive water will lead to stem rot.
Root development typically takes four to eight weeks. Check for successful rooting by gently tugging on the cutting; resistance indicates that new roots have formed and are anchoring the plant to the medium. Once roots are established, gradually acclimate the young rue plant to normal humidity levels by progressively opening the cover over several days, a process known as hardening off. The rooted cutting is then ready to be transplanted into a larger container or a permanent spot in the garden, where it will continue to grow into a mature rue plant.