House Plants Sexual Propagation

A number of common foliage and flowering house plants are easily propagated from seeds. These include umbrella tree, false aralia, tree philodendron, and many palms, cacti, and succulents. Many ferns, such as Boston, bird's nest, and maidenhair, can be propagated from spores.

Sexual propagation is relatively simply and inexpensive and can usually be done without special propagating structures. However, because sexual propagation depends on the uniting of genes from two parent plants, a certain amount of variation should be expected in the offspring. Seedling plants may vary considerably from the plant which bore the seeds.

Seed Propagation

Seeds of tropical plants generally require no pretreatment like those of temperate woody plants which may require moist chilling before germination can occur. In fact, seeds of tropical plants should generally be sown as soon as they mature.

Use a sterilized medium or commercial grade medium low in soluble salts such as milled sphagnum moss, vermiculite or a mixture of equal parts sand and peat moss. Almost any container with drainage holes can be used. Bottom heat (70° to 75°F) usually speeds up germination but is not essential; thermostatically controlled heating cables and mats come in several sizes and provide uniform heating.

Sow the seeds sparingly. If crowded together too closely, poor air circulation will increase the likelihood of damping-off, a fungal disease which attacks seedlings at the soil line. Extremely fine seeds should not be covered; larger seeds are usually covered to a depth about twice their size. It is a good idea to cover the container with glass or plastic to keep the medium from drying out. CAUTION: Remove the covering when seedlings appear. Label each flat or pot with the variety, planting date and other information you may desire. This provides a handy reference.

Check the seeds daily. Never allow them to dry out. Most seeds do not require light for germination. Filtered light is usually provided to germinating seeds, however, the light level should be increased when germination occurs, otherwise, weak, spindly seedlings will result. Seeds of many house plants are easily germinated under artificial light. Remember that the seedlings must be located close to the light source, usually not more than 12 inches in the case of fluorescent lamps.

Seedlings are transplanted more easily and with less "shock" when they are small. Most seedlings can be transplanted after the first true leaves appear. Dislodge the seedlings by lifting from below with a spoon or wooden label. Handle the seedlings by their root balls or by their leaves, NEVER by their stems. Replant them in their new container at approximately the same depth as they were growing and firm the soil around the roots. Water thoroughly and begin light fertilizer applications.

Planting Spores

Most ferns are propagated by division, but many can be propagated by spores which ferns produce on the underside of their fronds in structures called sori. The spores, which are the size of dust particles, should be scattered on the surface of a sterilized medium, usually one high in organic matter such as peat moss. Cover the container with a pane of glass or plastic to retain moisture. Place in a window receiving filtered light (rapid heating can occur under glass or plastic in direct light) or under artificial light. Be patient — it takes several weeks, sometimes months, for the young plants to germinate and reach sufficient transplanting size.