Cloning Plants:
Cuttings and Layering

Horticulture and the Science of Plants
Horticulture Youth Adventure Program

David Wm. Reed, Instructor
Department of Horticultural  Sciences

BACKGROUND

 

Cloning Plants Using Vegetative or Asexual Propagation

Vegetative or asexual propagation is the non-sexual reproduction or propagation of a new plant from vegetative organs (stem, root, leaf).The techniques used are cuttings  layering, division, grafting or budding.  We we use cuttings and layering.  The other type of propagation is seed propagation, which is also called sexual propagation.

 

Asexual propagation may lead to the formation of a clone.  A clone is defined as a group of plants that were all derived from the same parent and are propagated solely by asexual (vegetative) means, such as cuttings, layering, division, grafting or budding. All of the clones will be identical.  An example of a clone would be a group of plants that were all propagated as cuttings from the same plant. Many horticultural cultivars were propagated from a single seedling, from a single mutation that was found as a branch on a plant, or from a mutation artificially produced by plant breeders or geneticist. Since all subsequent plants were propagated from this single seedling or mutated organ, the entire cultivar is a clone. Examples are: 'Bartlett' pear, 'Queen Elizabeth' rose, and 'Golden Hahnii' Sansevieria. Some clones originated centuries ago. For example, 'Bartlett' pear originated in 1770.

 

Cloning Plants and the Controversy of Cloning Animals

Scientist have only recently learned how to clone animals.  The first animal cloned was Dolly the sheep.  Since then many different animals have been cloned, including cattle, cats, mice and monkeys.  It is rumored that some scientist are even trying to clone people.  Cloning of animals, especially people is very controversial.  However, we have been cloning plants for centuries and it is very common.  That is why when you go to a garden center, many of the plants look exactly alike.

 

Propagation by Cuttings

A cutting is a stem, root or leaf that is cut-off the parent plant and placed under favorable environmental conditions to regenerates new roots and/or shoots.  These new roots and shoots are called adventitious roots and adventitious shoots. This produces a new independent plant identical to (or a clone of) the parent. 

 

Cuttings are classified based on the plant part from which they are taken (stem, root or leaf) and their state of growth (herbaceous, hardwood, etc.).  The table on Types of Cuttings shows the different types of cuttings. Stem cuttings must form adventitious roots (they already possess shoots), root cuttings must form adventitious shoots (they already possess roots) and leaf cuttings must form both adventitious roots and adventitious shoots (they possess neither). 

 

Rooting Hormones Increase Root Formation

The cuttings of many plant species will form adventitious roots readily when placed in a glass or water or under  a water mist system. However, the cuttings of some plant species are very difficult if not impossible to root. Many of these difficult-to-root plant species can be encouraged to form roots with the use rooting hormones. See the table below on rooting kormones, which can be purchased at any garden center. The active ingredient in the rooting hormones is the plant hormone auxin.


 


 

Commercially Rooting Hormones (auxins)

Commercial

Name

Auxin

Active Ingredient

Concentration (ppm)

Formulation

Hormodin #1

IBA

1000

talc powder

Hormodin #2

IBA

3000

talc powder

Hormodin #3

IBA

8000

talc powder

Rootone

IBA 
M-NAA 
M-
NAM 
NAM

570 
330 
130 
670

talc powder

Rootone-F

same as Rootone 
plus fungicide

same as Rootone 
plus fungicide

talc powder

Rootone No. 10

NAM

4000

talc powder

Jiffy-Grow

IBA 
NAA

500 
500

solution

Chloromone

IBA 
NAA

500 
500

solution

Quick-Dip 
(home-made)

IBA (usually) 
in 50% alcohol

500-10,000

solution

 

Protect Cuttings From Drying-Out

When stem and leaf cuttings are removed from the parent plant they are cut-off from their source of water.  You must prevent the continued loss of water or many cuttings will desiccate (dry out) and eventually die.  For many plants this can be done by placing them in a shaded cool area away from direct sun or spraying the foliage with water several times per day.  This is sufficient for hardwood cuttings without leaves and for succulent plants and cacti.  Another method is to construct a rooting frame or humidity chamber, which is any box, pot, bench or tray enclosed by a polyethylene (plastic) tent in which the cuttings are placed.  The plastic covered humidity chamber cannot be placed in the sun or else it will overhead and kill the cuttings.  The best method is to use an intermittent mist system in which a very fine mist of water is automatically and periodically (intermittently) sprayed over the cuttings to decrease both water loss and heat build-up.

 

mist and humidity chamber

.

 


 

 

 

<>Propagation by Layering

Layering is a propagation technique where roots are induced to  form on a stem prior to the stem being cut-off from the parent plant. This is contrasted to cuttings, where roots are formed after the stem is cut-off from the parent plant. Layering is a common process in nature for many plants, such as blackberry, ajuga, and strawberry, which results in their self-propagation. Horticulturists have taken advantage of this naturally occurring process and have used it  for the propagation of many plant species. Layering is much less of a "shock" to the plant than taking cuttings. 

 

The basic principle underlying layering is stop the downward movement of sugars and hormones in the stem by either girdling, ringing, notching, tying or bending of stems, but at the same time to not stop the movement of water up stems.  Things move down stems in the tissue called phloem and up stems in the tissue called xylem. We will demonstrate to you how to cut the phloem but not the xylem.  The table on Types of Layering gives the various types of layering. 

.

TAKE HOME LESSONS

1) To learn how to propagate plants by cuttings. 
2) To learn how to used rooting powders on cuttings. 
3) To learn how to propagate plants by layering. 
.
MATERIALS NEEDED
A variety of plants to take cuttings.
Several types rooting hormones
A woody plant to demonstrate air layering.

PROCEDURES

1) How to make cuttings.

You will be shown how to take stem and leaf cuttings from a variety of tropical foliage plants and garden plants.  See the table on Types of Cuttings which has an image of all the various types of cuttings.  We will only propagate plants that root easily without needing to be under a water mist system. 

2) How to treat cuttings with rooting powders.

You will be shown how to treat  the base of the cutting with rooting powders in order to encourage them to form adventitious roots better. 

3) How to make an air layer.

How to air layer a woody plant will be demonstrated.  The table on Types of Layering, which has a picture of an air layer.

 


 

Types of Cuttings

LEAF CUTTINGS - must form both new adventitious shoots and roots (except leaf bud).

a) leaf bud

b) leaf petiole

c) leaf blade

d) leaf section

         

 
STEM CUTTINGS - must form new adventitious roots 

a) hardwood (left)
b) semi-hardwood  
c) soft or greenwood  
d) herbaceous 

 hardwood

semi-hardwood,

softwood 

or herbaceous

e) cane - a leafless stem 

cane 

f) rhizome - underground stem

rhizome 

g) tuber - underground storage stem

tuber

 
ROOT CUTTINGS
must form new adventitious shoots

root section 
  tuberous root

 

 


 

Types of Layering


air layer


simple layer


tip layer


serpentine layer


trench layer


mound or stool layer

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