Download Avocado Propagation

Fact Sheet HS-52
April 1994
Avocado Propagation1
Julian W. Sauls2
The avocado seed readily lends itself to home
propagation and few people can resist the temptation of
growing avocado plants from seed. There are two
different approaches to avocado propagation, depending
on whether the plant is to be grown as a houseplant or
for fruit production.
PROPAGATION AS A HOUSEPLANT
The seed from a fresh avocado will germinate within
a few weeks if given water, light, air and room
temperature. The easiest way to grow an avocado plant
is to insert 3 or 4 toothpicks horizontally into the seed
near the pointed or rounded end and suspend it (pointed
end up) over a glass of water, with about a third of the
seed submerged. The glass should be placed in good
light and the water replenished as needed. Germination
should occur in 2-6 weeks. The plant can be left in the
glass until the roots fill the container, when it should
either be planted in a pot with soil or discarded.
Avocado seeds can be planted directly into a pot
with soil for germination. A large pot 15-25 cm (6-10
in.) in diameter should be used. The pot may be plastic,
clay, ceramic or other material, but it must have a
drainage hole at the bottom. Any sterile, well-drained
potting soil is suitable.
Germination may be enhanced by removing the seed
coats or by cutting off the top centimeter (half-inch) of
the pointed end of the seed. The seed is planted pointed
end up to about half its depth. The pot is then placed in
a warm, well-lighted place and watered as needed.
To encourage branching and prevent the plant from
developing into a single-spindly stalk, the stem should be
cut back about half-way when it gets 15-20 cm (6-8 in.)
tall. Each resulting branch should have the tip pinched
off after growing 15-20 cm (6-8 in.) to encourage
multiple branching. Tip pruning should be repeated as
many times as necessary to develop the desired fullness.
Regular applications of a soluble houseplant-type
fertilizer coupled with good light and watering as
necessary will maintain the lustrous deep green foliage
characteristic of a healthy avocado plant. As with most
houseplants, the avocado can be moved outdoors to
shady locations during warm weather. Eventually the
plant will become pot bound and should either be
discarded, transplanted to a larger container or pruned
back severely.
PROPAGATION FOR FRUIT PRODUCTION
Avocados grown from seed rarely produce fruit
before 8 - 10 years, and such fruit may be of poor
quality. Commercial avocado orchards are planted with
budded or grafted trees of named varieties of known fruit
quality. The homeowner who wants an avocado tree for
its fruit production should either obtain a young grafted
tree from a local nursery or propagate his own. Budded
or grafted trees will produce fruit within 2 or 3 years as
1.
This document is Fact Sheet HS-52, a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and
Agricultural Sciences, University of Florida. Publication date: April 1994.
2.
Julian W. Sauls, Former Extension Horticulturist, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural
Sciences, University of Florida, Gainesville FL 32611.
The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national
origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office.
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean
Avocado Propagation
compared to the 8-10 or more years required of seedling
avocados.
Avocados may be propagated by several methods
which involve the use of rootstock and scions. The
rootstock provides the lower trunk and root system and
the scion forms the top of the plant. Rootstock plants
which are to be budded or grafted are usually seedlings
4-8 months old. Scion material for buds or grafts is
taken from a mature, bearing tree of the desired variety.
The necessary equipment consists of a very sharp
knife and wrapping material such as polyethylene
budding tape or an adhesive tape.
ROOTSTOCKS
Page 2
VENEER GRAFTING
Veneer grafting can be used anytime that stocks are
actively growing and budwood is available. The stock
is trimmed of its lower leaves and cleaned of any soil or
other foreign matter. A tangential cut 5-7 cm (2-3 in.)
long is made through the bark and just into the wood in
an area where the stem is straight, approximately 7-10
cm (3-4 in.) above the soil. A short second cut is made
at the base of the first one, forming a notch. A scion
with two or three buds and of equal or slightly smaller
diameter than the stock is prepared by making a slanting
cut on one side equal in length to that made on the
stock. A small cut is made at the base of the scion on
the opposite side so that the scion will fit into the notch
on the stock.
Commercial propagators in Florida use the largest
seeds possible, as these usually produce graftable stocks
sooner. Seeds are taken from cull fruit of West Indian
varieties which mature in late summer or early fall. Any
healthy avocado seeds will be suitable for home
propagation.
The scion is placed into position on the stock with
care to line up the juncture between bark and wood on
at least one side. The entire graft should be secured
with wrapping material in a spiral beginning at the
bottom, taking care to maintain alignment of the cut
edges of the stock and scion.
Avocados are commonly planted in large
polyethylene tubes filled with sterilized soil, but any
large pot with suitable drainage is adequate. Seed
should be planted as previously described and the
containers should be in full sun. The seedlings should
not be pruned, as grafting requires one large stem. Wellcared-for seedlings should attain graftable size, about 6
mm (¼ in.) in diameter, in a few months.
CLEFT (TIP) GRAFTING
BUDWOOD
Budwood for veneer grafting, side grafting and cleft
grafting is obtained from the terminals of small branches
on healthy, vigorous, mature, bearing trees of the desired
variety. Terminals should be dormant (not in a flush of
growth), or barely pushing, free of pests and have well
developed buds at the tip and along the side. Each
terminal is cut 10-12 cm (4-5 in.) back from the tip and
the leaves are trimmed to short stubs with pruning
shears.
Budwood for chip budding is collected from the base
of the current growth flush after it has matured and
hardened. Again, the leaves are trimmed to short stubs.
The same is true for budwood used in cleft (tip) grafting.
Budwood that is to be stored for several days should be
put in a plastic bag and placed in the vegetable drawer
of a refrigerator.
Cleft (tip) grafting can also be used for avocados,
using similar stocks and scions as previously described.
The top of the rootstock is cut off approximately 7 - 12
cm (3 - 5 in.) above the soil level, discarded and the
stock is then split 3 - 5 cm (1½ - 2 in.). A scion is
trimmed into a two-sided wedge with long tapering cuts
about equal in length to the cleft in the rootstock. The
scion is then wedged into the cleft in the stock and the
graft is wrapped securely, leaving the terminal exposed.
CHIP BUDDING
Chip budding uses a scion with only one bud instead
of the several buds previously described for grafting. A
thin slice of wood is removed from the stock about 7 10 cm (3 - 4 in.) above the soil line by making a smooth
downward cut 2 - 3 cm (1 in.) long and just into the
wood. A second cut is made at the base of the first one,
forming a notch. A chip with a scion bud is removed
from the scion in the same manner. The chip is then
inserted into the notch on the stock and securely
wrapped.
(Note:
Chip budding of avocados in
containers is often unsuccessful in Florida.)
Avocado Propagation
Page 3
FORCING AND AFTERCARE
TOP WORKING
The cleft graft will commence to grow without
assistance but the other propagations will require forcing
the buds into growth, assuming the scions are still
healthy and green. Forcing should be done 3-4 weeks
after propagation. The wrapping can be left on the
grafts for a month or more in warm weather or 2-3
months in cool weather, but it must be removed from the
chip bud during forcing. It can be removed easily by
cutting with a knife on the side of the stem opposite the
propagation.
Seedling avocado trees or potted plants are often
planted in the yard. Later it becomes apparent that the
seedling is not going to bear fruit at an early age and the
question of grafting with known varieties arises. Older
trees can be grafted or budded, but it becomes difficult
as the plant gets older. There are two options:
The best way to force the buds onto growth is to
make a horizontal cut into the stock 2-5 cm (1-2 in.)
above and on the same side as the scion. Then when a
scion bud has grown out several centimeters, the stock
can be cut off on a slant as near the scion as possible
with a sharp pair of hand shears.
Only one shoot is allowed to grow -- all others
above and below it should be removed as they appear.
The young shoot will need to be tied loosely to a stake
for support as it grows. The framework of the tree is
started when the scion is 30-45 cm (12-18 in.) tall. The
tip should be pinched off and 4-6 well-spaced lateral
branches are allowed to develop if natural branching
does not occur.
Budded or grafted plants can be planted almost
anytime after 6 months, but planting is usually delayed
for 12 - 18 months.
1. A vigorous, healthy tree may be cut off 1-3 feet
above the ground and painted (white latex and
water, 1:1) to protect it from sunburning. Several
sprouts will grow out from the trunk and one or
more can be grafted or budded as previously
described with scions of the desired variety.
2. A tree with a good framework can be cut back to
the main scaffold branches and painted (white latex
and water, 1:1) to protect it from sunburning. Either
the stubs or sprouts from the stubs can be budded or
grafted as previously described.
This will require two or three propagations per
branch and more intensive aftercare, particularly
regarding staking to prevent the young scions from being
broken off by winds. Frequently, one or two branches
are left intact for a year or more to sustain the tree and
shade the propagations until they have grown out
sufficiently.