It is amazing how the additional light that February brings causes growth on houseplants. Plants in a sunny window have to be turned daily to keep them from growing toward the light. This lush new growth may also be a signal to cut some plants back to keep them compact and bushy. However, those cuttings may be put to use. When taking cuttings, be sure to use sharp tools. You may use a knife or scissors, or by-pass pruners. Do not use anvil pruners, as they may crush the stem. If there has been any disease in your plants, sterilize your tools with a mixture of rubbing alcohol and water or a weak bleach solution between cuts to prevent the spread of pathogens.
Stem tip cuttings include the terminal bud and at least two nodes. The nodes will become the source of the adventitious roots. Some plants will produce the roots easily, but others will benefit from a little help. Rooting hormones are available in powder and gel forms. When using the hormones, put some out into a small dish. Do not dip your plants into the bottle. When using the powder, dip the stem cutting in water and then dip it into the powder, making sure that the nodes get some powder. Use a dowel rod or other stick just larger than the stem to make a hole in the moistened potting mix. Insert the cutting in the hole, and press the mix in to touch the stem. Depending on the plant, roots will usually form in two to three weeks.
Some stem cuttings do not even need soil to form adventitious roots. Impatiens, tradescantia and other common houseplants will root if the stem is just placed in water. However, experts say that healthier roots form when starting them in a sterile potting mix.
You do not need to waste the rest of the stem once you have used the terminal bud. You can take other types of cuttings along the length of the stem. Take a leaf bud cutting by making two cuts—one just above a leaf node and another just below the node. Your cutting should include a leaf, a node and an axillary bud (see last week’s list of terms). Dip it in water and then touch it to the rooting hormone. Plant it in a moist potting mix.
Plants with thick stems may be propagated by a special type of stem cutting known as a cane cutting. Sometimes, this is a good way to rejuvenate a plant that has become a little leggy at the top or has just outgrown your house. A stem may be cut into sections about four inches long. You may either stand the stem vertically in the potting mix or lay it horizontally. If using the horizontal method, make sure that about half of the stem’s diameter is beneath the soil line. This method may result in several new plants, which may be divided after they begin to grow, or you may let them grow as a cluster.
Some plants will produce roots from the leaf petiole. Many people use this method for starting new begonias. Simply place the cut end of the petiole in the starting medium. The cut will form a scab, and a new bud will emerge. That bud will become a new plant. Just remove the original petiole when the new plant emerges.
Some plants, including many succulents, will grow new plants by simply placing the end of a leaf in the growing medium. When using succulent cuttings, it is usually best to allow them to scab over before planting them. I usually break off a leaf and wait three to five days before planting them.
Like all plants, starts from cuttings require moisture and light. Make sure the growing medium stays evenly moist, but not soggy. The plants also require humidity. For that reason, cuttings are often put in plastic tents to keep the humidity up. They also need bright, indirect light. With the advent of the LED grow lights, supplying good light inside is easy and relatively inexpensive.