Philodendrons are among the most popular houseplants, celebrated for their lush, easy-care nature, and vining growth habit. When these plants grow, they naturally develop structures called aerial roots, which extend directly from the stem above the soil line. These specialized roots offer a highly efficient and reliable way to propagate new plants, providing a significant advantage over methods that rely solely on new tissue formation.
The Role of Aerial Roots in Philodendron Propagation
Aerial roots are a natural adaptation for philodendrons in their native tropical habitats, where they often climb up trees. These roots serve two primary functions: providing physical anchorage to a climbing surface and absorbing moisture and nutrients from the humid air and rain. The presence of an aerial root signals an active growth point, or node, on the stem.
The existing aerial root tissue is already programmed to develop into a full root system when given a consistent source of moisture. This pre-formed root structure at the node makes propagation more reliable and faster than waiting for an entirely new root to sprout from a plain stem cutting. When these roots are encouraged to grow in a moist medium, they quickly transition from their aerial form into the subterranean roots needed for water and nutrient uptake in soil.
Essential Preparation and Supplies
Before beginning any propagation method, gathering the necessary tools helps ensure a clean and efficient process. You will need a sharp cutting instrument, such as shears or a clean knife, which should be sterilized with rubbing alcohol before each use. This step is important for preventing the transfer of pathogens to the fresh wound on the mother plant and the cutting.
For encouraging root growth, you will need a suitable rooting medium, which varies depending on the method. Sphagnum moss is commonly used for air layering due to its excellent moisture retention. Water or a mix of perlite and potting soil are typical for cuttings, and you may optionally use a rooting hormone, which can accelerate the development of new roots.
Method One: Air Layering the Aerial Root
Air layering is a technique that encourages the aerial root to develop into a full root ball while the stem remains attached to the parent plant. This reduces shock and ensures the new plant has an established root system before being cut free. Begin by selecting a healthy node on the stem that has a noticeable aerial root extending from it.
Soak sphagnum moss in water, then squeeze out the excess moisture until it is damp. Wrap this moist moss completely around the node and the aerial root, creating a compact ball of medium. To keep the moisture locked in, wrap the moss ball tightly with clear plastic wrap or a small plastic bag, securing the ends with twist ties or tape.
This enclosed environment creates the high humidity the aerial root needs to grow quickly. Over the next several weeks, monitor the moss to ensure it remains consistently moist, adding water if needed through an opening in the plastic. Once you can see a dense network of new, white roots winding throughout the moss, the new plant is ready to be separated from the mother plant.
Method Two: Taking Rooted Cuttings
The traditional method of taking a cutting is most effective when you select a stem segment that includes an existing aerial root. Choose a section of the vine with at least one leaf and one node that has an aerial root bump or small root extending from it. Use your sterilized tool to make a clean cut on the stem about one to two inches below the chosen node.
If the cutting has multiple leaves, remove any lower leaves that would be submerged in the rooting medium, as this prevents them from rotting. You can then place the cutting into a container of water, ensuring the node and aerial root are fully submerged, or directly into a damp, well-draining medium like perlite or potting mix. If using water, change it weekly to keep it fresh and prevent bacterial growth.
Place the cutting in a location that receives bright, indirect light, which encourages root development. The aerial root will begin to swell and produce finer, water-absorbing roots within a few weeks. Once the new roots have grown to be about two inches long, the cutting has enough structure to survive the move to a permanent pot.
Transitioning and Long-Term Care
Once the propagated section, whether from air layering or a cutting, has developed a root system, the next step is transferring it to soil. For water-rooted cuttings, the transition can be shocking, so pot them in a well-draining soil mixture, such as a blend of potting mix and perlite. Keep the soil consistently moist for the first few weeks after planting to help the roots adapt to the new, drier environment.
If you performed air layering, cut the rooted section from the mother plant just below the newly formed root ball and plant it directly into the soil. Both new plants should be placed in the same bright, indirect light conditions they were rooted in, as this provides the energy for continued growth. Over time, you can gradually reduce the watering frequency, allowing the top inch or two of soil to dry out between waterings as the new plant establishes a stronger, soil-adapted root system.