Cow vetch, also known as Vicia cracca, has various methods to extend its numbers like putting seeds in soil, taking apart clumps, utilizing cuttings from stems, and taking parts of leaves to plant.
To make more plants by planting seeds, get mature seeds from existing plants and put them in drained dirt in spring or fall. Keep the soil slightly wet and make sure there's adequate sunlight so the seeds can begin to grow.
To separate the clumps of roots into smaller sections, carefully dig up the plant. Replant the divided sections in prepared soil, making sure each part has sufficient roots and shoots. Water thoroughly after putting them in the ground.
To use stem cuttings from healthy plants to make more plants, take 4-6 inch pieces from stems during spring or summer. Take off the lower leaves and dip the cut end in rooting hormone. Put the cuttings in a well-draining potting mix and keep them in a warm, humid place.
Leaf cuttings can also propagate plants. Take healthy leaves and cut them into pieces, being sure each section has a vein. Plant the leaf sections in a well-draining potting mix and keep them moist.
Seeds can be harvested when they are fully mature and dry. Collect the seed pods and let them dry out more before removing the seeds.
Using multiple ways to propagate increases the chances that propagation will be successful and allows more plants to be produced. Each method has pros and cons, so using a combination ensures higher success.