Asexual propagation is the best way to
maintain some species, particularly an individual that best represents that
species. Clones are groups of plants that are identical to their one parent and
that can only be propagated asexually. The Bartlett pear (1770) and the
Delicious apple (1870) are two examples of clones that have been asexually
propagated for many years.
The major methods of asexual propagation are cuttings,
layering, division, and budding/grafting. Cuttings involve rooting a severed
piece of the parent plant; layering involves rooting a part of the parent and
then severing it; and budding and grafting are joining two plant parts from
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The potting soil, or medium in which a plant grows, must be of
good quality. It should be porous for root aeration and drainage, but also
capable of water and nutrient retention. In order for a plant to form a new root
system, it must have a ready moisture supply at the cut surface. Oxygen, of
course, is required for all living cells. The coarse-textured media choices
often meet these requirements. Most commercially prepared mixes are termed
artificial, which means they contain no soil. The basic ingredients of such a
mix are sphagnum peat moss and vermiculite, both of which are generally free of
diseases, weed seeds, and insects.
Rooting media for asexual propagation should be clean and
sterile. Cuttings are not susceptible to damping-off, but they are attacked by
other fungi and bacteria which may come along in the medium. Most commercially
prepared media are clean when purchased.
The media should be low in fertilizer. Excessive fertility
will damage or inhibit new roots. High-quality artificial mixes sometimes
contain slow-release fertilizers.
Coarse perlite alone can be used to start some cuttings. This
doesn't hold much water for long, but it is fine for rooting cuttings of
cactus-type plants which would ordinarily rot in higher moisture media. Coarse
vermiculite alone has excellent water-holding capacity and aeration, but may dry
out rapidly via evaporation if not covered in some way. A mix of 50% peat moss
and 50% perlite favors good aeration. An equal mix of peat moss, vermiculite,
and perlite is also good and favors moisture retention.
Plain water can be used to propagate some cuttings. This is
possible and actually works quite well for some species which root easily. It
certainly provides the needed moisture, but if the water is not changed on a
weekly basis, it will become stagnant, oxygen deficient, and inhibitory to
rooting. Furthermore, roots produced in 100% water are different from those
produced in solid media; they may undergo greater transplant shock with a
greater incidence of death. So, it is not the most desirable methodfor most
plants, but certainly feasible.
Rooting Enhancement Conditions
Once you've selected the right medium, your first priority is to get roots
produced as quickly as possible. The consequences of slow rooting may be death
because the cutting must rely on its limited water reserves. Water is required
for major chemical reactions in plants which will be shut down in its absence.
Even though the exposed cells on the cut surface of the cutting ordinarily
transport water throughout the plant, they are not equipped to adequately absorb
it from the medium. This can only be done in most plants by roots, and
particularly root hairs. Root hairs are tiny, single cell projections from the
root ends or tips.
Make sure the medium is moist prior to inserting cuttings. If
incompletely moist, then the cut surface may contact a dry pocket and have its
own water absorbed away by the medium component. Try to keep both the air and
medium temperature warm: 70-75°F. Higher temperatures enhance growth, but
excessively high temperatures do not allow for photosynthesis to keep up with
food breakdown in normal cell energy use (respiration). You can buy electric
heating pads to put beneath containers holding cuttings to maintain a constant
Get air circulation around the cuttings as much as possible to
discourage fungal growth. Place in bright, but not direct light. An east window
is fine but a west window is too warm and a south facing window too bright.
North is too dim.
One way to provide good environmental conditions for asexual
propagation by cuttings is through the use of a mist bed. This system sprays a
fine mist of water over the cuttings once every few minutes, and the time is
adjustable. It should only be on during the day, as nighttime operation would
keep the medium too wet and encourage rotting. Misting inhibits transpiration
and forces the plant to conserve water while it forms new roots. If a mist
system is unavailable, one can be imitated in a small propagation tray in the
home. Choose an appropriate medium, moisten it, and place it in a tray. Place
the tray in a perforated or slitted clear plastic bag. This increases the
relative humidity and inhibits water loss by the plant and medium, yet allows
air circulation. Tug gently at the cuttings after 2-3 weeks to test for rooting
and transplant to individual pots when roots resist your tugs. Dig them out, do
not pull them out! Different plants require different rooting times, so do not
expect them all to root at the same time.
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Many types of plants, both woody and herbaceous, are
frequently propagated by cuttings. A cutting is a vegetative plant part which is
severed from the parent plant in order to regenerate itself, thereby forming a
whole new plant. Take cuttings with a sharp blade to reduce injury to the parent
plant. Dip the cutting tool in rubbing alcohol or a mixture of one part bleach
to nine parts water to prevent transmitting diseases from infected plant parts
to healthy ones. Remove flowers and flower buds to allow the cutting to use its
energy and stored carbohydrates for root and shoot formation rather than fruit
and seed production. With large-leaved cuttings (i.e., Rhododendron) and limited
space in the propagation container, trimming up to half the leaf length can
improve efficiency, as well as light and air circulation for all the cuttings.
To hasten rooting, increase the number of roots, or to obtain uniform rooting
(except on soft, fleshy stems), use a rooting hormone, preferably one containing
a fungicide. Prevent possible contamination of the entire supply of rooting
hormone by putting some hormone in a separate container for dipping cuttings.
Discard this hormone after all the cuttings are treated.
Place stem and leaf cuttings in bright, indirect light. Root
cuttings can be kept in the dark until new shoots appear.
Numerous plant species are propagated by stem cuttings. Most can be taken
throughout summer and fall, but stem cuttings of some woody plants root better
if taken in the fall or in the dormant season. Success with herbaceous plants is
generally enhanced when done in the spring; these plants are actively growing
then, and more apt to root quickly on their own. There are several different
types of stem cuttings depending on the part of the stem needed. At least one
node (the point on a stem where leaves are attached and buds form) should be
below the media surface. Although some plants root at internodes (the space
between nodes), others only root at nodal tissue.
Detach a 2- to 6-inch piece of stem, including the terminal bud. Make the cut
just below a node. Remove lower leaves that
would touch or be below the medium. Dip the stem in rooting hormone if desired.
Gently tap the end of the cutting to remove excess hormone. Make a hole in the
medium with a pencil or pot label, and insert the cutting deeply enough into the
media to support itself.
Medial cuttings (also stem-section cuttings)
Make the first cut just above a node, and the second cut just below a node 2 to
6 inches down the stem. Prepare and insert the cutting as you would a tip
cutting. Be sure to position right side up. Buds are always above leaves.
Make sure the cutting is inserted base down.
Cut cane-like stems into sections containing one or two eyes, or nodes. Dust
ends with fungicide or activated charcoal. Allow to dry several hours. Lay
horizontally with about half of the cutting below the media surface, eye facing
upward. Cane cuttings are usually potted when roots and new shoots appear, but
new shoots from dracaena and croton are often cut off and rerooted in sand.
The eye refers to the bud which emerges at the axil of the leaf at each node.
This is used for plants with alternate leaves when space or stock material are
limited. Cut the stem about 1/2 inch above and 1/2 inch below a node. Place the
cutting horizontally or vertically in the medium with the node just touching the
This is used for plants with opposite
leaves when space or stock material is limited. Cut the stem about 1/2 inch
above and 1/2 inch below the same node. Insert the cutting vertically in the
medium with the node just touching the surface.
This method uses stock material with woody
stems efficiently. Make a shield-shaped cut about halfway through the wood
around a leaf and axial bud. Insert the shield horizontally into the medium so
that it is completely covered. Remove any leaf blade but keep a portion of the
petiole intact for ease in handling this small cutting.
Leaf cuttings are used almost exclusively for a few indoor plants. Leaves of
most plants will either produce a few roots but no plant, or just decay.
Whole leaf with petiole
Detach the leaf and up to 1 1/2 inches of
petiole. Insert the lower end of the petiole into the medium. One or more new
plants will form at the base of the petiole. The leaf may be severed from the
new plants when they have their own roots, and the petiole can be reused.
(Example: African violet).
Whole leaf without petiole
This is used for plants with sessile
leaves (no stalk or petiole). Insert the cutting vertically into the medium. A
new plant will form from the axillary bud. The leaf may be removed when the new
plant has its own roots. (Example: donkey's tail).
Detach a leaf from the stock plant. Slit
its veins on the lower leaf surface. Lay the cutting, lower side down, on the
medium. New plants will form at each cut. If the leaf tends to curl up, hold it
in place by covering the margins with the rooting medium. (Example: Rex
This method is frequently used with snake plant and fibrous rooted begonias. Cut
begonia leaves into wedges with at least one vein. Lay leaves flat on the
medium. A new plant will arise at the
vein. Cut snake plant leaves into 2-inch sections.
Consistently make the lower cut slanted and
the upper cut straight so you can tell which is the top. Insert the cutting
vertically. Roots will form fairly soon, and eventually a new plant will appear
at the base of the cutting. These and other succulent cuttings will rot if kept
too moist. (Note that with variegated snake plant, the new shoot will develop
from cells that do not display the variegation.)
Root cuttings are usually taken from 2- to 3-year-old plants during their
dormant season when they have a large
carbohydrate supply. Root cuttings of some species produce new shoots, which
then form their own root systems, while root cuttings of other plants develop
root systems before producing new shoots.
Plants with large roots: Make a straight top cut. Make a
slanted cut 2 to 6 inches below the first cut. Store about 3 weeks in moist
sawdust, peat moss, or sand at 40°F. Remove from storage. Insert the
cutting vertically with the top approximately
level with the surface of the rooting medium. This method is often used
outdoors. (Example: horse radish).
Plants with small roots
Take 1- to 2-inch sections of roots. Insert the cuttings horizontally about 1/2
inch below the medium surface. This method is usually used indoors or in a
hotbed. (Example: bleeding heart).
Stems still attached to their parent plants may form roots where they touch a
rooting medium. Severed from the parent plant, the rooted stem becomes a new
plant. This method of vegetative propagation, called layering, promotes a high
success rate because it prevents the water stress and carbohydrate shortage that
Some plants layer themselves naturally, but sometimes plant
propagators assist the process. Layering may be enhanced
by wounding one side of the stem or by bending it very sharply. The rooting
medium should always provide aeration and a constant supply of moisture.
Dig a hole 3 to 4 inches deep. Insert the shoot tip and cover it with soil. The
tip grows downward first, then bends sharply and grows upward. Roots form at the
bend, and the recurved tip becomes a new plant. Remove the tip layer and plant
it in the early spring or late fall. Examples: purple and black raspberries,
Bend the stem to the ground. Cover part of
it with soil, leaving the last 6 to 12 inches exposed. Bend the tip into a
vertical position and stake in place. The sharp bend will often induce rooting,
but wounding the lower side of the branch or loosening the bark by twisting the
stem may help. Examples: forsythia, honeysuckle.
This method works for plants with
flexible stems. Bend the stem to the rooting medium as for simple layering, but
alternately cover and expose stem sections. Wound the lower side of the stem
sections to be covered. Examples: heart-leaf philodendron, pothos.
Mound (stool) layering
Cut the plant back to 1 inch above the
ground in the dormant season. Mound soil over the emerging shoots in the spring
to enhance their rooting. Examples: gooseberries, apple rootstocks.
Air layering is used to propagate some indoor plants with thick stems, or to
rejuvenate them when they become leggy. Slit
the stem just below a node. Pry the slit open with a toothpick. Surround the
wound with wet unmilled sphagnum moss. Wrap plastic or foil around the sphagnum
moss and tie in place. When roots pervade the moss, cut the plant off below the
Plants to Propagate
Propagation from the following plant parts can be considered a modification of
layering, as the new plants form before they are detached from their parent
Stolons and runners
A stolon is a horizontal, often fleshy stem
that can root, then produce new shoots where it touches the medium. A runner is
a slender stem that originates in a leaf axil and grows along the ground or
downward from a hanging basket, producing a new plant at its tip. Plants that
produce stolons or runners are propagated by severing the new plants from their
parent stems. Plantlets at the tips of runners may be rooted while still
attached to the parent, or detached and placed in a rooting medium. Examples:
strawberry, spider plant.
Plants with a rosetted stem often reproduce
by forming new shoots at their base or in leaf axils. Sever the new shoots from
the parent plant after they have developed their own root system. Unrooted
offsets of some species may be removed and placed in a rooting medium. Some of
these must be cut off, while others may be simply lifted off the parent stem.
Examples: date palm, haworthia, bromeliads, many cacti.
Separation is a term applied to a form of propagation by which plants that
produce bulbs or corms multiply.
New bulbs form beside the originally planted
bulb. Separate these bulb clumps every 3 to 5 years for largest blooms and to
increase bulb population. Dig up the clump after the leaves have withered.
Gently pull the bulbs apart and replant them immediately so their roots can
begin to develop. Small, new bulbs may not flower for 2 or 3 years, but large
ones should bloom the first year. Examples: tulip, narcissus.
A large new corm forms on top of the old
corm, and tiny cormels form around the large corm. After the leaves wither, dig
up the corms and allow them to dry in indirect light for 2 or 3 weeks. Remove
the cormels, then gently separate the new corm from the old corm. Dust all new
corms with a fungicide and store in a cool place until planting time. Examples:
Plants with more than one rooted crown may be divided and the crowns planted
separately. If the stems are not joined, gently pull the plants apart. If the
crowns are united by horizontal stems, cut the stems and roots with a sharp
knife to minimize injury. Divisions of some outdoor plants should be dusted with
a fungicide before they are replanted. Examples: snake plant, iris, prayer
plant, day lilies.