Plant Propagation
Sexual Propagation
Sexual propagation is by seed or spores. The plants will become fertilized and produce the seed that will grow into a new plant with both of the characteristics of the parent plants. Because of the traits given by the parent plants, sexual propagation offers these advantages:
- The only method when creating new varieties or cultivars.
- It is the easiest and cheapest way of growing plants.
- A way of getting rid of diseases.
- Some plants are only able to be produced via seed.
Propagation by seed also carries some risks. In order for seeds to grow, they must break dormancy and germinate. Sometimes, the seeds may be dead or have difficulty breaking dormancy. In order to overcome dormancy, horticulturalists may use scarification or stratification techniques.
Scarification is a technique that involves breaking or weakening the seed coat. This can be done by filing, scratching with sandpaper, or boiling in hot water.
Stratification is a technique that involves chilling the seed. In nature, some types of seeds may need to go through a cold season before germinating. Stratification replicates nature’s way of breaking dormancy. If any of these techniques are needed, the seed package should indicate this.
Sexual propagation also includes growth from spores. Spores are tiny dust-like seeds that grow on sporophytes (plants that produce spores as a means of reproduction). A common example is the fern. Spores grow on the underside of the leaves and disperse when ready.
To propagate ferns: Take a leaf from the fern, gently scrape off the spores, allow them to dry, and then sow them. It is recommended that fern spores are planted in sterile conditions because fungus and bacteria are very competitive with spores for space.
Asexual Propagation (Vegetative Propagation)
Asexual propagation does not require seeds. Instead, a portion of the parent plant’s vegetation is used to grow a new plant. This produces genetically identical clones.
Cuttings
Cutting a portion of a leaf, stem, or root off the parent plant and replanting it so the plant begins to grow. This is the most common and widely used form of vegetative propagation.
Grafting
Grafting combines a scion (a piece from the desired variety) with the stock/rootstock of another plant. This method is primarily used with woody plants. Common types include cleft, tongue, saddle, and budding.
Layering
Allowing the plant’s stolons or runners to root themselves and grow into independent plants. Common examples include vines and spider plants. Air-layering is done on a branch: cut the branch open, surround the wound with moist soil medium, wrap with plastic, and sever once roots form.
Division
Separating a plant through the roots and replanting the newly divided sections.
Banana Propagation
FAMILY: Musaceae
SCIENTIFIC NAME: Musa sp.
ORIGIN: Asian tropics
The banana plant is a large perennial herb with leaf sheaths that form trunk-like pseudostems. It typically has 8–12 leaves up to 9 ft long and 2 ft wide. Root development can be extensive (up to 30 ft laterally in loose soil). Flower development begins from the underground corm 9–12 months after planting. The inflorescence grows through the center of the pseudostem. Fruits develop parthenocarpically (without pollination) into clusters called “hands.”
Propagation by Division (Suckers/Pups)
Bananas are propagated vegetatively because nearly all cultivated varieties are seedless. The principal method for small-holder farmers is division of suckers (pups) that arise from the base of the main stem or underground corm. Large suckers (at least 3 feet tall) are preferred. Remove them from vigorous clumps during warm months using a spade, ensuring some roots remain with the pup. Plant close to the surface and trim large leaves, leaving only the youngest leaves.
Tissue Culture (Micropropagation)
Advanced micropropagation techniques produce large numbers of disease-free, clonal plants rapidly — often thousands to millions per year. Direct regeneration pathways and scalp techniques are used for high multiplication rates. This is currently the most rapid method for producing valuable disease-free banana plantlets for distribution to farmers.
Minisetting
A rapid, inexpensive technique to multiply tissue-cultured banana plantlets (or germinated yam seeds) for large-scale commercial distribution to farmers.
Ginkgo Propagation
Propagation by Cuttings
Take cuttings about 15 cm long during May–July (young or half-ripe wood). Stick them in soil medium, keep moist, and they should root. This is a reliable way to determine the sex of the tree.
Propagation by Grafting
Branches of male trees are grafted onto female trees to fertilize them. Grafting is not the preferred method because ginkgo trees normally have a dominant central leader (topophysis).
Propagation by Seed
Gather seeds in the fall (wear latex gloves — the fleshy coating contains toxins). Remove the fleshy coating, wash thoroughly, and let dry. Store in the refrigerator until planting. Scarification is required: mechanically scarify with sandpaper, knife, or file, then soak in warm water for 24 hours. After soaking, treat in 10% bleach solution for about 10 minutes to protect against fungus, then rinse well. Sow in moist soil. Seeds germinate in 30–60 days.
Pomegranate Propagation
Propagation by Seed
An easy and fast method. Seeds germinate quickly, even when sprinkled on the soil surface. They have little dormancy issue because pomegranates are native to warm climates. However, seedlings are not true-to-type and may lose desirable qualities of the parent cultivar. Seed propagation is rarely used for large-scale production because it takes longer to reach fruiting size.
Hardwood Cuttings (Most Widely Used)
Take cuttings November–January from one-year-old wood. Cuttings should be 6–10 inches long. Treat with rooting powder and place in a well-drained medium or grow cube. A mist house or greenhouse produces well-rooted plants quickly. Cuttings are exact clones of the mother plant.
Detailed Grafting Techniques
Because flowers on trees or shrubs are cross-pollinated, plants grown from seed do not have the same characteristics as the parent. Vegetative propagation (especially grafting) is necessary to propagate a particular cultivar true-to-type.
Grafting success requires three elements: good technique, healthy plant material (scion and rootstock), and a sharp knife.
Key Grafting Terms
- Scion — A detached twig or shoot (usually last year’s growth) containing 2–4 buds. This is the top part of the graft.
- Stock (Rootstock) — The portion to which the scion is attached (a root, seedling, or tree with top removed).
- Cambium — The thin layer of living cells between the outer sapwood and inner bark. Cambium layers of scion and stock must be in firm contact to unite and grow together.
Bark Graft
A simple, rapid method suitable for amateurs. Best performed in spring when the bark slips easily from the wood. Use dormant scions. Cut the stock to a stub, make a vertical cut through the bark, lift the bark slightly, and insert the prepared scion (long slant cut on one side, shorter cut forming a wedge). Secure with grafting tape or rubber and cover all cut surfaces with grafting wax.
Cleft Graft
Excellent for top-working older trees (branches 1–3 inches in diameter). Cut the stock back to a smooth section and split it vertically down the center. Prepare scions with a two-sided wedge (one side slightly thicker). Insert two scions per cleft so the cambium layers align, then wrap securely.
Whip-and-Tongue Graft
The most common method for nursery stock (under 1 inch diameter). Make matching long slanting cuts on stock and scion, then add interlocking “tongues.” Align cambium layers (match on one side if sizes differ) and wrap tightly.
Side Grafts (including Side-Veneer)
Used for large-scale propagation of conifers and deciduous plants. A shallow cut is made on the side of the stock; the prepared scion is inserted. Wrap tightly and heal in a high-humidity grafting case.
Tip: Always use a very sharp knife, keep scion and stock cambium layers in firm contact, and protect the graft union with tape and grafting wax.
Frequently Asked Questions
What is the difference between sexual and asexual plant propagation?
Sexual propagation uses seeds or spores and combines genetics from two parents, creating new varieties. Asexual (vegetative) propagation uses parts of the parent plant (cuttings, grafting, layering, division) to produce identical clones without seeds.
How are banana plants typically propagated?
Bananas are propagated vegetatively using suckers (pups) from the base of the plant or underground corm. Tissue culture (micropropagation) and minisetting are used for large-scale production of disease-free plants. Cultivated varieties are mostly seedless and develop fruit parthenocarpically.
What is tissue culture propagation for bananas?
Tissue culture, or micropropagation, is the most rapid method for producing thousands to millions of disease-free, clonal banana plants per year. It uses laboratory techniques with high multiplication rates through direct regeneration and scalp methods, ideal for commercial distribution.
How do you break seed dormancy using scarification and stratification?
Scarification weakens the seed coat by filing, sandpaper, or hot water. Stratification chills seeds to mimic winter conditions. These techniques help seeds germinate when they have difficulty breaking dormancy naturally. Check seed packets for specific requirements.
What are the main types of grafting techniques?
Common grafting methods include Bark Graft (simple, spring only), Cleft Graft (for top-working trees), Whip-and-Tongue Graft (best for small nursery stock), and Side Grafts (including side-veneer for evergreens). Success requires aligning the cambium layers of scion and stock.
How do you propagate pomegranate plants?
Pomegranates are easiest from hardwood cuttings (6–10 inches from one-year-old wood in winter) treated with rooting hormone. Seed propagation is possible but plants are not true-to-type and take longer to fruit. Cuttings produce exact clones of the parent.
How do you grow ginkgo trees from seed?
Collect seeds in fall (wear gloves due to toxic coating), remove flesh, wash, and dry. Scarify mechanically, soak 24 hours in warm water, then treat with 10% bleach for 10 minutes. Sow in moist soil after refrigerating. Germination takes 30–60 days.
What is air layering and how is it performed?
Air layering is a form of layering done on a branch while still attached to the parent plant. Cut the branch open, surround the wound with moist soil medium, wrap with plastic, and wait for roots to form (usually a few weeks). Once roots are mature, sever and plant the new section independently.
