Propagating plants means creating new plants from existing specimens, and is an important part of permaculture. It means that you can have a self-sustaining site; you can preserve local, indigenous and heirloom species, and cut the cost of buying seeds, seedlings or new plants. There are several methods that gardeners use to propagate plants.
Seeds are the natural way flowering plants reproduce. The plants produce flowers, which either contain both male and female parts (stamens and pistils, respectively) in one bloom or have separate flowers for the male and female organs. The flowers get pollinated when pollen is transported from one plant’s stamen (male organ) to another’s pistil (the female equivalent). This can occur via the wind or, more commonly, by insects visiting the plants and inadvertently carrying pollen off to another plant. (It is to attract these pollinating insects that flowers are coloured, shaped and perfumed in different ways, as well as providing nectar.) Once this happens a seed develops in the female parts of the plant.
Growing plants from seeds is one of the easiest methods of propagating species. You can buy seeds cheaply, but also harvest them from an established garden or source them from a seed bank. Seed can also be stored in the refrigerator, sometimes for years, until you are ready to plant it. However, some plants can take a long time to mature from seed to adult.
To grow plants from seeds, the most common method is to plant them in containers with a growing medium free of harmful insects and pathogens. A small amount of compost can help, but most importantly the containers and soil must drain well as waterlogging is harmful to seed development.
As a general rule, plant the seeds at a depth four times that of the size of the seed (although, some plants require surface sowing) and keep moist but not damp. The majority of perennials, annuals and vegetable will germinate best when kept at a temperature between 65 and 75 degrees Fahrenheit. When seedlings sprout give them a good amount of light until they grow strong enough for planting in the garden.
Another method available to permaculturists to propagate plants from their garden is tasking a cutting. This means cutting off a stem from a living plant and allowing it to develop its own root system. Take cuttings from healthy stems with no flower buds on them, and cut at a 45-degree angle so that the potential rooting surface is maximized.
Most plant cuttings need to be planted in a soil-less posting mix, one that drains well, and placed in a warm place. Most like direct sunshine for at least part of the day. While you want to avoid the soil getting waterlogged, cuttings often benefit from increased humidity. You can achieve this by placing the cutting in a plastic bag or cover with a glass container. All being well, new roots should begin to form after four weeks or so, and can be transplanted to larger containers or a sheltered nursery spot in the garden.
Grafting is a more advanced method of propagation, and involves the splicing of a stem from one plant onto the root system of another. The tissues of the two plants will then fuse, allowing the stem to benefit from the nutrients and water being absorbed by the rootstock.
While different plants may require variations, the general method of grafting is to select a healthy stem that contains at least one bud, and cut it on the diagonal. Make an equivalent diagonal cut in the rootstock (these diagonal cuts increases the surface areas in contact with one another and so help to create a stringer joint) and insert the stem. Bind with tape or twine so that the stem and rootstock remain in contact (avoid grafting in areas prone to high winds). Graft at the start of spring and the new stem should begin growing within around a month.
Budding is a form of grafting. Rather than using a stem, a single bud is taken from one plant and grafted into the rootstock of another. A similar technique is required to grafting, with the bud inserted into a cut in the rootstock. Typically, a ‘T’ shaped cut is made in the rootstock and the bud, attached to a small rectangle of stem is slipped inside. The bud then needs to be taped up.
For budding, choose mature buds for the best chance of success, and for most plants, perform the procedure as fall turns to winter. That way, your bud should grow when spring comes around. Budding is often used to propagate fruit species.
Propagation by division involves separating a whole plant into several smaller pieces, each of which can then become new, independent plants. It works best with mature specimens and, indeed, can help more mature plants to have a longer active life. It also provides more plants to utilize in different areas of the garden or in different guilds. Division is commonly used for species whose roots grow in clumps or crowns, and so offer obvious dividing points. These include many ferns and bamboos.
A few days before dividing a plant, water it thoroughly. This reduces the stress on the plant. Dig around the perimeter of the plant and extract it from the ground. Use a sharp blade to separate the root into pieces (there will usually be obvious ridges or grooves that lend themselves to division) and place each in a bucket of water. Plant each new specimen in a hole as deep as the one from which you took the original plant. Add some compost to help them get established, and water well. Divide either early in spring or early in fall, to give the new plants time to establish themselves before the heat of summer or cold of winter. Add mulch to feed and protect the new plants, but if planting in spring, allow some space around the new stems so the soil is able to get warmed.