Right now, while tropical plants are at their best in the temperate zone, take a forward look on the calendar. In just 8 or 10 weeks, lows in places like Ames, Iowa, will reach into the 40’s, right into the danger zone for truly tropicals plants. Conventional wisdom teaches us to bring potted trops indoors about 2 weeks prior to temperatures below 50 degrees. This allows the plants to acclimate before heating systems and fireplaces are in use to further dry out their environment. Sometimes the sheer size of tropical plants makes moving them difficult and some mature trops do not take the transition well, either, regardless of size. It will be longer than that before my area begins to cool down, but I am cloning now for a fall plant sale. The process is the same.
Some tropicals to root now have green stems but at this rampant stage of growth, they are too green to root in water. The roots may be plentiful, but they will also be quite thin. Instead, I am using the plastic rooting boxes described in this blog a few weeks back to root coleus, fibrous begonia, offsets from several succulents, philodendron, and pothos ivy. Coleus will drop leaves and often bring mealybugs with them into the house, but young plants take right to a sunny windowsill. My coleus are too tall anyway and if I pinch the tips for cuttings they will thicken up. I count 10 different varieties with at least 2 cuttings each, or one large box full. I can take tip cuttings with no more than 2 sets of leaves and go further down the stem to make cuttings with 2 more sets. That takes less than half off the mother plant and stimulates its growth for a big fall show. Fibrous begonias work the same way, but succulent offsets will need a drier box to nestle into while rooting. I use a smaller box and twice as much perlite for these little beauties, whether they are true offsets taken from the base of Haworthia or a Kalanchoe leaf with tiny plantlets around its edge. The ivies will root at each node along their growing stems as well as at their tips. I like to cut between leaves so there is an inch of stem on each side of the leaf to give it greater stability in the box. A 15 second dip in Hormex Liquid Concentrate gets these green stems on their way and I add a few drops to the clay pot reservoir twice a month to give them all they need. Be sure to ventilate the rooting box daily in hot weather and to close it tight when rain is expected if you are cloning outdoors.
Tropicals with woodier stems need a different approach, including blue butterfly flower, mandevilla vine, and the subtropical coral shrimp plant and laurel bay. The better stem for rooting these is behind the fleshy tip growth. The next several nodes along the stem behind the tip are much easier to root with this method. And once again, none of these plants tolerates indoor life as well when mature. You can protect the pots from freezing and hope that the top survives or will regrow, but the insurance of a newly rooted plant is comforting in a very cold winter. I take a cutting about 6 inches long and remove the green tip entirely, leaving about 4 inches to root. Roll the slanted tip in Hormex and slip 2 inches into the rooting mix. Remove or trim leaves only as necessary. I root the bay individually because each will grow into a small tree and they do not transplant easily once rooted. The others, like their green-stemmed counterparts, can be cloned in the covered rooting boxes so long as they are not crowded together.
I’m especially proud of my success with bay and use the leaves in cooking all the time. Cuttings have a bad rep among grower friends, but I get 8 out of 10 to root using my method. That’s enough to hold my head up, and plenty for the plant sale.