When a plant is difficult to root from a cutting because it is very woody or has a fleshy cane, try layering. By rooting your clone while it is still attached to its mother plant, you can take advantage of mama’s vascular system. The flow of water and nutrients will only be slightly impeded by the layer and will continue to sustain the stem you are cloning so you don’t have to. Air layers use long fibered sphagnum moss to make a damp rooting zone around a slit you have cut in the stem, while ground layers only bury part of the stem to encourage rooting. Both techniques work because the clone is still attached to the mother plant, and it makes your task much easier to do.
Summer is for layering, a form of propagation that relies heavily on time and technique to be successful. When it comes to layering, there is no substitute for practice and many plants are at just the right growth stage for it now. I’m layering figs, both edible and ornamental, but they are just examples of what is possible now, at the height of the growing season. Gather a few needed items and get busy!
Layering works because of one universal principle: wounding triggers biochemical survival mechanisms. You can think of it as the plant version of fight or flight, the adrenaline response in threatened mammals. We’ve all heard of people who are able to lift automobiles off of their loved ones, and soldiers who continue to defend their comrades despite their wounds. My only brush with such power came during a move when a refrigerator dolly slipped going upstairs and my husband was trapped underneath the appliance. Without thinking, I squeezed my shoulder into the small space available and lifted more weight than I ever imagined possible so he could roll out from underneath. Thanks to adrenaline, we managed to prop the fridge up on the porch rail, retrieve the dolly and finish moving in. I didn’t even get a bruise!
Auxin hormones control many aspects of plant growth and were the first plant hormones ever discovered. Their presence and levels throughout a plant will stimulate or repress depending on complex triggers. Cell growth and division, the way a particular plant organizes itself into leaves, buds, etc., and phenomena like apical cell dominance depend on auxin movement to occur. APC varies which explains why some plants put on new growth only at the tips of branches and others sprout at every node. It also explains why trees like cedars will usually die if their tops are cut out. Their apical dominance is so intense that removing the growing point stops them cold. Other plants can continue to grow without their central leader but will grow sideways or send branches weeping downward instead of up. For example, to maintain desirable cascading habits in plants like weeping mulberry you are advised to clip off any shoots that grow straight up. That tip is not just to keep them from looking like impish spiked hair – it continues the suppression of apical dominance. All of this may seem irrelevant, but it is not. Both the techniques and choice of plant parts to layer depend on it.
The best air layers are made on healthy plant stems at least 1 inch in diameter and held stiffly above ground. Woody plants like my edible fig trees with mature, inflexible stems are good candidates as are plants that grow from thickened canes such as corn plant and Janet Craig Draceanas. I must confess there is a sad JC struggling on a porch in my neighborhood that could be layered easily and recover its previous glory at the same time. Its 8 inch pot is inadequate for the 7 foot tall specimen with 2 fat stems and huge crowns of sadly weeping, sunburned leaves. There are clumps of leaves at the top of each stem and more a few feet lower down the cane. If I could make air layers along the stems below the top growth and above the lower, the 2 babies would be new plants and with some basic TLC, the mother could recover. Layering depends on healthy tissue and enough auxin to make the classic wound reaction, so time is of the essence here. I’m hoping to see JC out by the trash pile so I can save it, but not if too much time passes and the plant dehydrates completely.
To make an air layer, gather these items: sharp knife, ½ gallon of water in a small bucket, long-fibered sphagnum moss, 1 square foot of clear plastic, 2 twist ties, 1 toothpick, and Hormex Liquid Concentrate. Select a place below the top growth on the bare plant stem that is about 6 inches long. Add 1 teaspoon of HLC to the water and soak 2 handfuls of moss and the toothpick in the bucket for 15 minutes. Make a half inch slit across the stem and wedge it open with a piece of the soaked toothpick. By forcing open the slit, you hinder the natural auxin process that would regenerate the wounded vascular system and by soaking the toothpick in HLC you redirect the biochemistry in the wound in favor of root development. Squeeze out most of the excess water and press the moss into and around the wound to form a football shaped clump that extends 3 inches above and below the slit. Wrap plastic around the moss mass and secure it above and below with twist ties. Now, make another – remember, this is all about practicing to master the techniques – and make a note on your calendar to check on the air layer in about one month. Depending on the plant in question, you may be able to see white roots through the plastic as they grow in the moss. Smile, but wait until you see numerous roots before cutting the clone from its mother. Might be a month, might be 3, but time is on your side so use it.
Next week: Part 2: how to make ground layers that will really grow.
Nellie Neal is a passionate propagator and owner of GardenMama, Inc. She advocates for gardening 24/7 at her website, www.gardenmama.com. Ask questions and comment about this blog on the Contact Us page of www.hormex.com.
My friend swears by willow water for his roses. He soaks the cuttings in it for several hours before potting up. I root roses and everything else with Hormex products, but you may find it interesting to know that willow not only has IBA but also SA, another plant hormone found in aspirin. Here’s a recipe for willow water:
Gather young stems with green or yellow bark and strip the leaves off.
Cut the stems into 1 inch pieces
Cover with boiling water and steep overnight OR
Cover with tap water and soak for several days
Strain the liquid and put it in an airtight container
Store in the refrigerator
Use within 2 months
Put a ‘use by’ date on the bottle to avoid disappointment!
I’m preparing to do an updated version of my popular program about plant propagation and thinking long and hard about the subject. It seems to me that every time we slip a cutting into a glass of water or a pot of soil, it seems to me that we are continuing the chain of civilization. That may sound crazy to you, but bear with me and I will explain in this blog.
According to archaeologists and the fossil record, our human ancestors were nomadic. They wandered sometimes vast landscapes in search of food, moving on to elude threats like dangerous weather and predators. Over time they developed patterns that returned them to good hunting areas and to fruitful places in time fashion to harvest ripe fruits and nuts. Few populations can be considered truly nomadic today; long ago they planted themselves in communities organized around these food sources. When something changes, it changes, and this development changed the way people saw themselves and their commitments to one another. Settlements became permanent and what is known as modern civilization began when humans took responsibility for a particular place and its inhabitants. The need to feed more people coupled with a preference for this berry over that one inevitably led to farming and its necessary adjutant, propagation.
Eventually, smart people in disparate places worldwide learned to save seed for the next season and to dig up the little sprouts that appeared near favored trees and to plant them. They figured out any extra they had was worth something to someone else and traded for the other’s extra. So began trade and the valuable crops got propagated more often so their distribution spread. If you are with me here in the ‘WayBack’ machine, you realize that these events took centuries, but stay with me for one more leap in time to the 17th century Dutch Golden Age. The rules of supply and demand plus human greed came together and a single tulip bulb became so prized that it was worth an estate full of furniture plus a wagonload of money. Bulb growers and professional growers today express confidence that no one plant specimen will ever be so dear again, thanks in part to advances in plant propagation.
Somewhere along the way, trial and error taught us humans that some plants are easy to grow, others not. No doubt we employed any number of strategies to improve the odds. One of the best early options still in use today is willow water, made from the bark of any species of willow tree (Salix). Who knows how the eager propagator figured out that a willow branch roots very quickly in water and added other trimmings to it with good success. Or when someone noticed that the willow tree cut down for other purposes soon pushed out lots of sprouts that could be used in the same way. The discovery was made, the process refined, and by the 20th century, scientists analyzed the willow water in their quest to figure out how and why things work.
Not surprisingly, the stimulus provided by willow water is due to strong levels of IBA (indolebutyric acid) and SA (salicylic acid). Further analysis determined that it is the plant hormone IBA that does the most to promote rooting and some began to synthesize it commercially. Not all rooting powders are the same and in 1959, Gary Brooker developed the formulation now known as Hormex. He met the challenge of creating a compound that worked quickly and consistently with his Hormogenization process, a Proprietary Process that is exclusive to Hormex, Inc. today.
By the way, SA is related to the modern analgesic, aspirin, and is a plant hormone that triggers the defense mechanisms that repel pathogens. Perhaps that’s why my mother always put an aspirin tablet in a vase of cut flowers. She claimed a florist told her to do that, a tale I believe. She was a woman who cherished cut flowers whether in an elaborate arrangement, a classic florist’s box, or clipped from the garden for a pitcher on the kitchen table. She passed that love on to me, along with her vase collection which now numbers near 50 of every size and shape!
An unusual intersection of issues came to me last week and their answers led me to this blog. A neighbor got new carpet that’s a priority over the big clay pots that used to go inside each winter. A reader asked if it is possible to make a rooting chamber without a mist system. The answer to the first dilemma is to provide shelter outdoors for the big pots and propagate them so the small plants can live indoors more easily. And yes, it is possible to fashion an enclosed propagation box that has no mist system. While some plants are difficult to root without mist, many green stemmed (herbaceous) and woody cuttings will root in a humid chamber.
I have built several different sorts of these boxes, most in congregate settings indoors, but have never been satisfied. With some research and a bit of tinkering for size and soil capacity, I’ve come up with some ideas that will work for both gardeners and me, too. I hope you will try this simple idea, make it your own, and let me know how it goes.
Here are the things you will need and how they work together to create a rooting chamber.
- Clear Plastic Box. A propagation chamber needs to be tall and deep enough to accommodate the cutting and the rooting medium. You need at least an inch of rooting media below the base of the cuttings and another above their top. That means if you take a six inch cutting and want to put 3 inches of stem into the media and 3 above it, the clear plastic box must be at least 8 inches from base to lid inside. My friend with the tropical plants to root may need that size, but smaller cuttings can be rooted in a clear plastic shoe box. Large or small, the box and its top need to be clear plastic to capture the full spectrum of light, to make cleaning more efficient, and often for the cool opportunity to see roots growing.
- Soilless Rooting Mix. The preferred rooting medium for this enclosed system is soilless, a combination of peat and perlite in equal portions. Individual elements and prepared mixes are both readily available. As with any peat/perlite product, it is important to wet the product to reduce its dustiness and get it wet enough to start the cuttings on their way.
- Rooting Hormone. I like to set the rooting box on a larger tray to make a space to prepare cuttings. That gives me a place to put the plants, a paper plate with Hormex Rooting Powder on it or a cup of Hormex Liquid Concentrate. It is essential for success to stick cuttings in one motion and the setup allows me to do that. Make a fresh cut on the stem, apply the rooting hormone, and slip the cutting into the mix in the box.
- Watering System. Cuttings must have adequate water to keep the process going, and it can be tricky to keep conditions moderated. Overwatered cuttings can rot and fungus can grow on saturated soil in this warm, humid environment. Dry cuttings and media are just about useless; the plant material is even harder to rehydrate than the soilless mix. It’s nerve racking to water the soil in a box like this from the top with a small nozzle. The answer is a reservoir or other way to get water into the soil consistently without disturbing the cuttings or flooding the soil. I have used rolled up wick material like that used by African violet fanciers and sponges formed into a rolls at the corners of the box. But I like the small clay pot waterer best of all I have tried. Prepare a small clay pot by sealing its drain hole. I used bathtub caulk this time because it was handy but any kind of sealant will do. This is a good project for a recycled pot, since a new one will need to be sanded lightly to break up any coating that may have been applied to it.
Assemble these items, grab a bucket, a trowel, and some water. It’s wise to don a dust mask before pouring the fresh rooting mix into the bucket. Add water to the dry mix slowly and mix as you go with the trowel until the mix is evenly damp. Position the clay pot at the center of the plastic box and fill in around it with moist mix. A dot of fresh caulk on the already-closed drain hole will hold the pot in place nicely. Dip the base of each cutting into undiluted Hormex Liquid Concentrate or roll it in Hormex Rooting Powder, depending on the type of cutting and your preference. (Click here to see what strength powder to use if you are unsure.) Fill the pot with water. If your tap water has issues such as high pH or mineral content, sediment, or other contaminates, use distilled water or boil the tap water and cool to room temperature before using it. Replace the water as it is absorbed into the mix and occasionally add 2 drops of HLC to provide nutrients and a boost to the rooting process. Keep the top on the box and watch for condensation to build up inside. Open the box to vent it – you don’t want to create enough moisture to drip. I just lay the top sideways for a few hours to let fresh air in or you can prop it open with a chopstick or something similar. Keep the entire setup in the shade and check for signs of rooting like new leaves or white roots that you can see through the clear box. Should neither happen, gently tug on the cutting. If it is dark at the soil surface and comes right out, toss it. If it resists, it is rooting and you can relax.
Or more properly, cover it and your nose, too, when working with dry materials like peat and perlite. These two make a fine rooting mix in a 1:1 ratio, and bagged mixes are available as ‘soil-less potting mix’ like the Metro Mix products. Their packages seem to weigh nothing because they are bagged very dry and are incredibly dusty. You know you should wear a dust mask when mowing and trimming and this is another task you do not need to inhale. Don your mask and pour the mix into a bucket, add water slowly and stir with a trowel until the mix is damp. Fill pots, flats, or a rooting box with the mix. It is essential for success to stick cuttings in one motion: Make a fresh cut on the stem, roll it in Hormex Rooting Powder dip in Hormex Liquid Concentrate, and slip the cutting into the mix.