Spearmint (Mentha spicata) is a highly aromatic perennial herb valued for its refreshing flavor in cooking and beverages. It is one of the simplest herbs to multiply because of its vigorous, spreading nature, making it an ideal candidate for even novice gardeners. Spearmint’s rapid growth means that propagating new plants, whether to increase your stock or to refresh an old patch, is a reliable process. These methods allow gardeners to easily maintain a continuous supply of young, flavorful foliage.
Propagation via Stem Cuttings
Propagating spearmint from stem cuttings is a straightforward method that clones the parent plant. Begin by selecting a healthy, non-flowering stem approximately three to six inches long from the tip of the plant. Using clean shears, make a precise cut just below a leaf node, which is the slightly swollen point where a leaf pair emerges. This node contains the meristematic tissue necessary for root development.
After taking the cutting, carefully remove the lower sets of leaves, ensuring that only the top two or three pairs remain. This prevents submerged leaves from rotting in water and directs the plant’s energy toward forming new roots. Cuttings can be rooted using two primary methods: placing the cut end in a glass of clean water or directly into moist potting mix.
If using the water method, submerge the lower inch of the stem, keeping the container in a spot that receives bright, indirect light. Change the water every few days to maintain oxygen levels. Alternatively, insert the cutting directly into a well-draining, soil-less mix, ensuring at least one node is buried beneath the surface. With either technique, small white roots should develop within one to two weeks.
Propagation via Root Division
Root division offers an efficient way to multiply spearmint when you have a mature, established patch that needs rejuvenation. Spearmint spreads aggressively via rhizomes, which are horizontal, underground stems that generate new shoots and roots. This dense network makes the plant an excellent candidate for division, a process best performed in early spring or early autumn.
To divide the plant, use a garden fork to carefully lift the entire root ball or a sizable clump from the soil. The root mass will be tight and fibrous, composed of soil and interwoven rhizomes. Using a sharp spade or knife, cut the root ball into smaller sections. Ensure that each new piece contains a healthy cluster of roots and at least one or two active growth points.
These separated divisions can then be replanted immediately into their new locations. Dividing an overly dense root system provides the new plants with fresh space and resources, helping to reinvigorate the parent plant and encourage more vigorous growth. This method yields larger, more established plants much faster than starting from small cuttings.
Establishing New Spearmint Plants
Once the cuttings have developed roots at least a half-inch to two inches long, or the divisions have been separated, they are ready for permanent planting. Gently transplant cuttings rooted in water to avoid damaging the fragile new root hairs. The young plants should be placed in a location that receives full sun or light afternoon shade for optimal flavor and robust growth.
Spearmint thrives in consistently moist, well-draining soil, which should be thoroughly watered immediately after transplanting to settle the soil around the roots. For cuttings started indoors, a period of hardening off—gradually exposing them to outdoor conditions over a week—is recommended before final planting. This acclimates the young foliage to the harsher elements of wind and direct sun.
The plant’s aggressive nature, driven by its spreading rhizomes, necessitates a strategy for growth management. To prevent spearmint from spreading uncontrollably and crowding out other plants, growing it in containers is advisable. If planting directly into the ground, consider using a root barrier, such as a bottomless bucket or a plastic border sunk eighteen to twenty-four inches deep, to restrict the lateral expansion of the rhizome system.