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Saturday, March 10, 2012

Plant Propagation by Leaf, Cane, and Root Cuttings: Instructions for the Home Gardener

by Katarina Eriksson, Horticulturist. 2012
Guest Instructor, March 11, 2012
Types of Media used for propagation: (All equipment cleaned and sterile if possible)
½ sand with ½ good potting soil, or;
½ sand with ½ moistened peat moss, or;
⅓ sand with ⅓  perlite and ⅓  vermiculite, or;
⅓  peat with ⅓ perlite and ⅓ vermiculite.
(The propagation medium should be thoroughly moistened before use. Many organic materials, like peat moss, resists wetting at first (aquaphobic ). Be sure to apply warm water slowly while mixing to obtain uniform distribution. This may require 2-3 applications. It is not uncommon for a medium to look wet on the surface but to be powdery dry in the middle. A well moistened media will make it easier to stick cuttings later on.)

Some, but not all, plants can be propagated from just a leaf or a section of a leaf. Leaf cuttings of most plants will not generate a new plant; they usually produce only a few roots or just decay. Because leaf cuttings do not include an axillary bud, they can be used only for plants that are capable of forming adventitious buds (axillary bud refers to structures that develop in an unusual place). Leaf cuttings are used almost exclusively for propagating some indoor plants and succulent . There are several types of leaf cuttings:

Remove a leaf and include up to 1 1/2 inches of the petiole (The stalk attaching the leaf blade to the stem). Insert the lower end of the petiole into the thoroughly moistened medium (Figure 1). One or more new plants will form at the base of the petiole. The new plants are then severed from the original leaf-petiole cutting. Examples of plants that can be propagated by leaf-petiole cuttings include: African violet, begonia - rhizome types, Christmas cactus, gloxinias, hoya, peperomia, rubber plant, and sedums.  
1. With a clean sharp knife, remove a healthy leaf and at least 1 ½ inches of the petiole or leaf stem.
2. Hold the leaf gently and dip the cut end of the petiole into a rooting hormone.
3. Insert the petiole of the leaf into an appropriate medium at a 45 degree angle. Since new plants develop at the base of the leaf it is important that the leaf does not shade the new plants.
4. Increase the humidity around the cuttings. For a single pot use a clear plastic bag propped up with pencils. When using a standard black seedling tray, a clear plastic humidity dome works well. Bottom heat of about 75 degrees F should be provided if possible. Also recycled food plastic boxes.
5. Once the new plants have formed, (Figure 1) in approximately 8 weeks, carefully separate each new plant from the parent . Avoid damaging the delicate roots. It is these new plantlets which form around the stem which are used to transplant. The old leaf can be discarded or composted. Sometimes is a mass of clusters of plantlets.
6. Transplant each new plant into a 2 ½ -3 inch pot, using a lightweight potting soil and water thoroughly. Then pot up each stage to the size you want.
Figure 1.

Leaf without a petiole
This method is used for plants with thick, fleshy leaves. The snake plant (Sansevieria), a monocot, (Monocot seedlings typically have one cotyledon seed-leaf, like a blade of grass) can be propagated by cutting the long leaves into 3- to 4-inch pieces. Insert the cuttings vertically into the medium.
African violet, is a dicot, (a group of flowering plants whose seed typically has two embryonic leaves or cotyledons as seedlings.) can also be propagated from the leaf blade itself. Cut a leaf from a plant and remove the petiole. Dip in hormone, Insert the leaf vertically into the medium making sure that the midvein is buried in the rooting medium (Figure 2). New plant(s) will form from the midvein. Remember...if cuttings are stuck upside down they will not root. Leaf cuttings can be literally crowded together, almost shoulder to shoulder. This crowding will not harm them, and once the root systems have been developed they can be separated for transplanting into individual pots.
Other plants: Aloes, Cactus (particularly varieties producing "pads" like Bunnies Ears), Crassula (Jade Plant), Kalanchoe, Peperomia, Plectranthus (Swedish Ivy), Sedum and many other succulents.
 Figure 2.  Take a healthy leaf. Cut the leaf into sections, each with a main vein.

Split-vein and leaf wedge
Detach a leaf from a rex begonia and remove the petiole. Make cuts on several prominent veins on the underside of the leaf (Figure 3). Lay the cutting, lower side down, on the medium. If the leaf curls up, hold it in place by covering the margins with rooting medium or staples. New plants will form at each cut. A variation of this method is to cut the leaf into wedges, (Figure 3b) so that each piece has a main vein. The leaf wedge should be inserted into the media with the main vein partially covered. (I prefer this method)
Figure 3.  Slit leaf cuts and (2) new plantlets forming
Figure 3b. Wedge cuts

Leaf-bud Cuttings
Leaf-bud cuttings are used for many trailing vines and when space or cutting material is limited. Each node on a stem can be treated as a cutting. This type of cutting consists of a leaf blade, petiole, and a short piece of stem with an attached axillary bud. Place cuttings in the medium with the bud covered (1/2 to 1 inch) and the leaf exposed (Figure 4). Examples of plants that can be propagated in this manner include: clematis, rhododendron, camellia, jade plant, rubber plant, devil’s ivy, grape ivy, dracaena, blackberry, mahonia, and heart-leaf philodendron, English Ivy, pothos, Pelargoniums-Geraniums. Plant material selected for leaf cuttings should be
healthy, actively growing and free of insect or disease problems. Large, mature leaves provide the best source of propagation material.
Figure 4. The stem portion produces roots, and a new shoot develops from the bud
(Notes: Many plants will easily root in water. However, the roots that form can be extremely fibrous and stringy. Plants rooted in water often have a difficult time becoming established after they are transplanted to a container.)

The propagation medium should be thoroughly moistened before use. Many organic materials, like peat moss, have a waxy outer coating that resists wetting. Be sure to apply water slowly to obtain uniform distribution. This may require 2-3 applications. It is not uncommon for a medium to look wet on the surface but to be powdery dry in the middle. A well moistened media will make it easier to stick cuttings later on.
Light is an important environmental factor in plant propagation. Generally speaking, low light levels cause plants to root slowly. However, high light intensities can stress cuttings, causing them to burn or drop leaves. Diffused sunlight generally provides enough light for optimum rooting without causing injury to the cuttings.
Since cuttings do not have roots, they cannot replace the water lost through transpiration. Therefore it is important to maintain high humidity around the cuttings to cut down on the amount of moisture lost to the atmosphere.
These conditions can be provided by placing a clear piece of plastic over the propagation area. This causes condensation to form on the underside of the plastic that provides the necessary humidity. Adequate ventilation is also required to avoid disease problems. The plastic covering should be placed such that air can flow freely around the cuttings as they root. Also you can recycle plastic food containers (Good for the Earth)
For best results, maintain day temperatures at 70 degrees F. During winter months, soil can be as much as 10-20 degrees less than air temperature, so provide bottom heat when possible. Ideal rootzone temperatures for most plants are approximately 70-75 degrees F.
Rooting Hormones:
Rooting hormones are often used to promote root formation. These materials provide supplemental auxin, a naturally occurring plant hormone that is responsible for root development. The basal end of the cutting is dipped into the chemical prior to sticking it into the propagation medium. These products come in different strengths and will vary according to the type of plant being propagated.

Auxin, a naturally occurring plant hormone, stimulates root formation.
Several synthetic forms of auxin are sold as "rooting hormone." Though some plants will root readily without treatment, application of rooting hormone to the base of the cutting will often improve your chance for success.
Two synthetic auxins, IBA (indolebutyric acid) and NAA (naphthaleneacetic acid) are most frequently used. They are available in several concentrations and in both liquid and powder form. 1,000 ppm (0.1%) is used most often for herbaceous and softwood cuttings; 3,000 ppm (0.3%) and 8,000 ppm (0.8%) are used for semi-hardwood and hardwood cuttings. Liquid formulations can be used at low or high concentration for softwood or hardwood cuttings, respectively. To determine the appropriate concentration for your cutting, follow the instructions on the product label and the general guidelines just given, or consult the references listed at the end of this publication.
IMPORTANT: To use rooting hormone, place the amount needed in a separate container. Any material that remains after treating the cuttings should be discarded, not returned to the original container. These precautions will prevent contamination of the entire bottle of rooting hormone.

Home made organic rooting hormone

The active ingredient of many commercial rooting products is Indolebutyric Acid (IBA), a natural plant hormone and and Salicylic acid (SA) (which is a chemical similar to the headache medicine Aspirin) is a plant hormone which is involved in signalling a plant’s defences. When you make willow water, both salicylic acid and IBA leach into the water, and both have a beneficial effect when used for the propagation of cuttings. One of the biggest threats to newly propagated cuttings is infection by bacteria and fungi. Salicylic acid helps plants to fight off infection, and can thus give cuttings a better chance of survival. Plants, when attacked by infectious agents, often do not produce salicylic acid quickly enough to defend themselves, so providing the acid in water can be particularly beneficial. (Do not use Aspirin, too many other chemicals, not organic)
  1. Get a handful of willow twigs (any Salix species will do) Collect young first-year twigs and stems of any of willow (Salix spp.) species, these have green or yellow bark. Don’t use the older growth that has brown or gray bark. Remove all the leaves, these are not used.
  2. Take the twigs and cut them up into short pieces around 1" (2.5cm) long.
  3. The next step is to add the water. there are several techniques to extract the natural plant rooting hormones:  a) Place the chopped willow twigs in a container and cover with boiling water, just like making tea, and allow the “tea” to stand overnight.                           b) Place the chopped willow twigs in a container and cover with tap water (unheated), and let it soak for several days.
  4. When finished, separate the liquid from the twigs by carefully pouring out the liquid, or pouring it through a strainer or sieve. The liquid is now ready to use for rooting cuttings. You can keep the liquid for up to two months if you put it in a jar with a tight fitting lid and keep the liquid in the refrigerator. Remember to label the jar so you remember what it is, and write down the date you brewed it up, and to aid the memory, write down the date that it should be used by, which is two months from the date it was made! You can also freeze it.
  5. To use, just pour some willow water into a small jar, and place the cuttings in there like flowers in a vase, and leave them there to soak overnight for several hours so that they take up the plant rooting hormone. Then prepare them as you would when propagating any other cuttings.
  6. Now remember since this method isn't very exact, the strength of the willow water can vary depending on the time of year, the number of twigs, the concentration of hormones in the twigs, and the amount of time that the twigs were soaked. You will, however, still get a solution that will help your plants root.

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