I often get calls from people that have corn plants (Dracaena fragrans 'Massangeana') or dragon trees (Dracaena marginata) that have gotten too tall for their apartments. Because they have grown these plants for so long and have become attached, they do not want to simply throw the plant out and start over, and I understand that completely. Therefore, I am most often asked is there a way to cut off the top of the plant and have it establish roots to be replanted?
The answer is there are a few ways of propagating a new plant from an overgrown parent plant. The first is a method called air-layering. This is a practice I learned in horticulture school designed to grow new roots on the existing stalk or bark of the parent plant before you severe it and place it in a new container. When air-layering, you begin by making an incision in the main stalk at an angle and inserting in the incision moistened sphagnum moss. In some cases, depending on the plant species, adding a rooting hormone is recommended as well. Then the cut and the sphagnum moss must be wrapped in plastic or cellophane so that it is kept constantly and evenly moist. Once roots have established from the initial wound, then the plant can be cut below that point and planted in a new container to eventually grow into its own. This process can take a number of weeks for sufficient root growth, but you can be certain that the section of plant will survive when you then remove it from the parent plant and plant it on its own. The drawback to air-layering is that you have to have a bandaged plant in your home that may not be so attractive. The other drawback is that this process takes some time and I must be perfectly honest and say that most of the people I deal with admit that they do not have the patience to attempt air-layering.
With that being said, there is another option for propagating a Dracaena from the parent plant. This alternative method is to propagate by stem cuttings. Granted it might not be as reliable as air-layering, but this anyone can do, and chances are you will still be able to continue growing the plant you have come to love. Here are a few pictures to help you through the process. This exercise I am doing here in the office as an example and I will keep you posted as to the development of new roots as they happen over time.
For this exercise, you will need a bag or regular peat moss, or a soil-less mix of ¾ peat moss and ¼ vermiculite. You will also want a plastic pot and saucer to place your cuttings in as plastic retains moisture for longer than terra cotta. If the peat moss or soil-less mix is dry, be sure to moisten it before you begin.
First locate on the parent plant a length of stem and leaves that is 4”-6” in length.For the best chance of root development and the plants survival, you need the cuttings to have some foliage so that the plant can continue to photosynthesize once it has been cut. With a sharp knife, severe this top portion of foliage and stem at a slight angle and separate it from the parent plant. For dragon trees (Draecaena marginata) some books suggest letting the cuttings sit for 24 hours, but for corn plants (Dracaena fragrans ‘Massangeana’) do not let the cuttings sit and dry out. I should say that this is also best done in the spring or summer when the plant is actively growing. Now place your cutting in your container of peat moss or soil-less mix. Remember that you need a long enough cutting that you can anchor it in the new pot with at least an inch of the stem submerged in the moist substrate. In addition, you may choose to remove or cut back a few leaves as well. Because the parent plant has many established roots, it can have an equally large amount of foliage; this is what horticulturists call the root-to-shoot ratio. Since you have removed the roots, you must pare down the foliage because this plant will have to essentially start over from scratch. If the plant is photosynthesizing like crazy and there are no roots to balance the flow of nutrients, then the plant can go into major stress and die. In addition, if you have an option, take your cuttings from the smaller shoots, as younger tissue often has better and quicker recuperative potential. Keep your cutting in the soilless mix and keep it evenly moist, watering it a few times each week. On the flip side, do not keep the mix sopping and saturated because you do not want to run the risk of rotting the cutting and losing the plant once you have come this far. As you would with any plant, keep the cutting in a spot with bright, indirect light and good air circulation. After 8-10 weeks your cutting should establish new roots and begin to live as a plant of it’s own. Once the cutting and roots have outgrown the container, repot it in a larger container in the spring.