UNIVERSITY
Of
FLORIDA
IFAS EXTENSION
Palm
Seed Germination
Alan W.
Meerow
Palms are unique
among woody ornamental plants because, with relatively few exceptions, palm
species can only be propagated from seed. Palms are also notorious in the
nursery trade for slow and uneven seed germination. It has been estimated that
over 25% of all palm species require over 100 days germinating and
having less than 20% total germination (Tomlinson, 1990). The reasons for this
remain obscure, as very little investigative work has been accomplished on seed
dormancy conditions in palms. Nonetheless, the palm grower can maximize success
with germinating palm seeds by paying careful attention to a number of basic
guidelines. The purpose of this publication is to outline and discuss the
various aspects of handling and germinating palm seeds in the most
cost-effective and reliable manner possible.
The
Palm Seed
Palm seeds vary tremendously with
respect to size. Many palms have seeds no larger than 1/4 inch in diameter,
while the largest seed of any flowering plant in the world is that of a palm
(the double coconut, Lodoicea maldivica). The bulk of a palm seed is
taken up by nutritive tissue called endosperm that provides food for the
germinating seedling for a longer period of time than most flowering plants
(Figure 1). The "milk" and white meat of a coconut are liquid and solid
endosperm, respectively. The palm embryo is very small, either cylindrical or
top-shaped. The seeds themselves may be either round or variously elongated.
Their surfaces may be smooth or intricately sculptured. Some are surrounded by
a hard, water- and air-impermeable coat. Fibers from the fruit wall frequently
remain attached to the seed, even after cleaning.
Types
of Palm Seed Germination
The way palm seeds germinate falls into one of two categories. In
palms with remote germination (Figure 2a-c), the seedling axis develops
at some distance from the actual seed. The first structure to emerge from the
seed is called the "cotyledonary petiole." It resembles, and many people
mistake it for, the first seedling root. The cotyledonary petiole grows
downward into the soil (sometimes very deeply) and swells at its base. From
this swelling emerges the first seedling root (radicle) and seedling shoot
(plumule). The actual cotyledon or seed leaf remains inside the seed,
functioning as an absorptive organ called the "haustorium." The haustorium
transfers nutrients from the endosperm to the young seedling. In palm seeds
with remote germination, the radical persist for some time and produces lateral
roots. The seeds of
Mediterranean fan palms (Chamaerops humilis), Chinese fan palms (Livistona
chinensis), date palms (Phoenix spp.) and Mexican fan palms (
Washingtonia robusta)
have remote
germination. The other main class of palm seed germination is called adjacent
germination (Figure 2d-f).
In these seeds, only a small portion of the cotyledon emerges from the seed. It
appears as a swollen body abutting the seed surface and is called the "button."
The radicle and plumule emerge from the bottom and top of the button. In palms with
adjacent germination, the first seedling root or radicle is usually narrow and
very short lived and is quickly replaced by roots formed at the seedling stem
base (adventitious roots). As with remote germination, a haustorium remains
inside the seed absorbing food from the endosperm. Some common palms with
adjacent germination include areca (Dypsis lutescens), King Alexander
palm (Archontophoenix alexandrae) and coconut (Cocos nucifera). In
coconut, however, the first stages of germination occur in the fibrous fruit
wall that adheres to the seed. They cannot be observed without de husking the
nut. A number of palm species (Bismarckia, for example) bury the
seedling axis deep in the soil. These species require some special
handling that will be discussed later in this circular.
Figure
1. Longitudinal and
cross section through a coconut fruit.
seedling. In palm seeds
with remote germination, the radicle persists for some time and produces
lateral roots.
Figure 2. Main
classes of palm seed germination. A-B. Remote germination, date palm (Phoenix
dactylifera). A. Early germination with cotyledonary petiole emerged and
seedling root (radicle) beginning growth. B. Seedling stem (plumule) emerging
from cotyledonary sheath. C. First leaf (eophyll) emerged, radicle continuing
to elongate, and haustorium inside seed absorbing nutrients from endosperm.
D-F. Adjacent germination, piccabean palm (Archontophoenix cunninghamiana). D.
Early germination with button emerged. E. Seedling root (radicle) and stem
(plumule) emerging from button. F. First leaves (eophylls) emerging, first
adventitious root formed and supplanting radicle, and haustorium inside seed
absorbing nutrients from endosperm.
Sources of Seed
Seeds may be
collected from local sources (trees in the landscape) or purchased from
commercial dealers. Local collection has
certain advantages; the freshness, degree of maturity and parentage of the seed
is usually known by the collector. If the seed will be stored, the collector
will be controlling the methods used and the duration of storage.
Commercial dealers can usually offer larger quantities and a greater diversity
of species.
Commercial dealers will also be handling the time consuming chores of seed
cleaning, which may require special equipment. However, the age and ultimate
germination percentage of purchased seed is frequently unknown. Testing a
sample of commercially available seed before purchase is a wise precaution (see
next section).
Seed
Maturity
With few exceptions seed should be
collected when the fruit is completely ripe (showing full color), or as soon as
it falls from the tree (Figure 3). A few exceptions have been noted. Seed from
green fruits of queen palm (Syagrus romanzoffiana) germinate better than
seed from half-ripe or ripe seed (Broschat & Donselman, 1987), perhaps due
to inhibitors in the fruit. Seed of royal palm (Roystonea regia) from
ripe fruits germinated more slowly than seed from half-ripe or green fruits,
but fewer of the unripe seed ultimately germinated (Broschat & Donselman,
1987).
Figure 3. Queen palm (Syagrus romanzoffiana) fruit
harvested from the tree and ready for processing.
Viability
of Palm Seed
Viability of
palm seeds can vary among trees of the same species, and even from year to year
from the same tree. Age of the seed and/or the storage methods used (see next
section) can directly influence the ultimate germination percentage. Seeds of
some palms generally remain viable for only 2-3 weeks (e.g., latan palms, Latania spp.), while others may retain
viability for over a year (areca, Dypsis lutescens) if stored properly
(Broschat & Donselman, 1986). It is a good idea to test sample seed lots
for viability before purchasing large quantities. Some growers advocate using a
seed float test. The seeds are placed in water and those that float are
discarded as inviable. However, some palm seeds naturally float because they
are dispersed in nature by water. Furthermore, some growers have found that if
the floating seeds are planted, a sizable number will germinate. There are two
recognized ways to quickly test seed viability on a random sample of the entire
lot:
Observation
Cut open a
sample of the seeds. The endosperm should be firm and the tiny embryo should
fill its chamber (located at one end of the seed). If the endosperm is soft and
spongy; or the embryo shriveled, discolored, or absent; or if the seed coat
appears to have deteriorated, then the seed is probably inviable (Figure 4).
Figure 4. Cross
section through viable (right) and inviable (left) seed of Areca palm (Dypsis
lutescens). Note shrunken endosperm and embryo in seed on left.
Tetrazolium
Chloride Test
Mix a 1% (10 gm/l) aqueous solution of tetrazolium chloride
(available from any chemical supplier). Cut a sample of the seeds in half to
expose the embryo and place the half containing the embryo in the solution. Put
the container in the dark for at least 2 hours (a full day is sometimes
required). If the embryo stains partially or completely red or pink, it is
probably viable. If there is no stain, the seed is likely inviable.
Cleaning Palm Seed
Palm seeds are enclosed by a fleshy
or fibrous fruit wall (mesocarp) that, with few exceptions, must be removed
prior to storage or planting (Figure 5). Uncleaned seeds of areca palms (Dypsis
lutescens) have been known to germinate if planted immediately upon
harvest. Coconut seed does not require husking before planting (in fact, the
seedling germinates within the fruit before emerging).
If only a small number of seeds are to be processed, they can be cleaned by
hand, using a knife to cut away the fruit tissue. For large quantities, machine
cleaning is advisable. Species (Areca, for example) having relatively thin
fruit walls can be cleaned easily by rubbing seeds across a strong, large mesh
screen while rinsing with a hose to remove the mesocarp, or by rubbing off the
fruit wall by hand in a bucket of water and rinsing.
A number of palm species have an irritant in the fruit pulp (calcium oxalate
crystals) that can make cleaning by hand a painful experience. Gloves should be
worn when handling fruits of the following: all Caryota (fishtail palms), most Chamaedorea,
Carpenteria acuminata, Roystonea species (royal palms), and Arenga (sugar
palms).
Most palm seeds require a soak in water to first soften (ferment) the fleshy
fruit wall (Figure 6). The water should be changed each day if possible. The
fruits are ready for processing when the mesocarp yields easily to finger
pressure. The fruits are then placed in a commercial seed cleaning machine
which abrades the fermented mesocarp from around the seed. The pulp is washed
from the cleaning chamber and collected below. A small cement mixing machine
partially filled with coarse sand or gravel works fairly well (Figure 7). In
both cases, water is continuously rinsing the seeds as the machines operate.
Hard or very fibrous palm fruits can be cleaned by mixing the fruits with
gravel or rock and repeatedly stepping on them. Similarly, some palm species
with very hard seeds have been cleaned by driving a truck or other vehicle over
burlap bags of the softened fruits. Cleaned seeds should be air dried before
storage.
Figure 5. Cleaned
(left) and uncleaned (right) seed of queen palm (Syagrus romanzoffiana).
Figure 6. Palm fruit soaking in water
to soften the mesocarp.
Figure 7. Cement-mixing machine used
to clean palm seeds. Gravel inside the machine abrades the fruit pulp from the
seed.
Storage
of Palm Seed
With few exceptions, it is best to
plant palm seed shortly after cleaning. If this is not possible, the best
general storage procedure is to dust cleaned and air-dried seed with thiram
(Thylate®) or captan, seal the seed in plastic bags, and store at 65-75°F. There is some evidence that maintaining this covering
of fungicide when the seeds are sown may negatively influence germination (Meerow,
1994). Seeds of most tropical palms will lose viability if stored at
temperatures below 60°F.
Broschat and Donselman (1986, 1987, 1988) found that cleaned seed of Areca (Dypsis
lutescens) could be stored at 73°F
for over 1 year without significant loss of viability, royal palm (Roystonea
regia) for 9 months, queen palm (Syagrus romanzoffiana) for 4
months, and pygmy date (Phoenix robelenii) for 8 months. In the case of
royal palm, up to 9 months of storage actually increased germination relative
to planting fresh seed immediately.
Seeds of pindo palm (Butia capitata) actually require a period of dry
storage for optimum germination (Carpenter, 1988b). The duration of the period
increases with decreased temperature: 90 days at 77°F, 120 days at 59°F, and 150 days at 41°F. Generally, palms from
seasonal climates (versus uniformly tropical) may have greater tolerance for
low temperature storage. Seeds of the native silver palm (Coccothrinax
argentata) and thatch palm (Thrinax morrisil) have withstood -4°F and 15°F respectively for one week
without loss of viability (Carpenter, 1988a; Carpenter & Gilman, 1988).
Seeds of more tropical species (areca, Dypsis lutescens, for example)
may be killed after storage for 24 hours at 40°F (Broschat &
Donselman, 1986).
Pretreatment
Before Planting
Due to the often slow and uneven
germination of palm seeds, there has been a great deal of interest in any
pre plant treatments that might speed germination or result in more even rates
of germination. For the commercial palm grower, the value of seed pretreatment's
must be weighed against the additional labor costs involved. A fairly universal recommendation has been to soak
palm seed in water for 7 days. It is
advisable to change the water daily. Such a pretreatment is useful only after
dormancy requirements (if any) have been met, though few palm species have been
tested for indications of seed dormancy. The seed must be planted immediately
after the treatment, as storage following water imbibition may induce a secondary
dormancy. One researcher germinated seeds of fifteen species of the genus Copernicia entirely
in water (Kitzke, 1958). Not all species respond positively to a water soak
treatment (Broschat & Donselman, 1987, 1988; Carpenter, 1987, 1988; Doughty et al. 1986;
Odetola, 1987), and experiments
documented in the literature have rarely tried varying the duration of the
presoak period on seeds of the same species. However, unlike some of the other
pretreatment's described below, a water soak poses little danger to the seed.
Soak in
Gibberelic Acid (GA3)
Excessive
elongation of Areca palm (Dypsis lutescens) seeds on left was caused by
pre treating seed with a presoak of gibberelic acid (GA3).
A number of investigators have
reported a hastening affect on germination by soaking seed in 10 to 2000
parts-per-million (ppm) concentration of GA3 for 1 to 3 days (Doughty et al.,
1986; Nagao & Sakai, 1979; Nagao et al., 1980; Odetola, 1987). One study found
10-25 ppm worked well for a wide variety of species (Odetola, 1987). However,
treatment with this growth regulator causes excessive elongation of the
seedling (Figure 8), in some cases even preventing the seedling from supporting
itself (Broschat & Donselman, 1987, 1988). Consequently, it is not
advisable to use a GA3 presoak despite any positive effects on germination
rate.
Scarification
Scarification of palm seed involves
thinning the bony endocarp of palm seeds that may impede imbibition of water.
It may be accomplished mechanically, by abrading the surface of the seed until
the endosperm becomes visible, or by soaking the seed in dilute to concentrated
sulfuric acid (H2504) for 10 to 30 minutes. Scarification has increased the
rate of germination of a number of palm species with hard, water-impermeable
seed coats (Holmquist & Popenoe, 1967; Nagao et al., 1980; Odetola, 1987).
The danger in mechanical or acid scarification is damage to the embryo during
the process. The practice should be reserved for seeds with hard and
impermeable seed coats. Species that have slow or uneven germination without
scarification should have seed scarified on a trial basis before the entire lot
of seed is treated.
Sowing Palm Seed
Containers
A variety of
germination containers can be used for palms seeds, including pots and flats.
Pots are better than flats due to the deeper soil column and better drainage.
For very deep-rooted species, and especially those that bury the seedling axis,
tree tubes, lengths of PVC pipe, or other improvised containers have been used
to provide the extra depth that these seedlings require during early
development. Some growers prefer to sow seed in large raised beds constructed
from wood or cinder blocks. The most important consideration for any
germination container is that it allows adequate drainage of excess water from
the medium.
Medium
Palm seed germination media must be well-drained,
yet have some moisture-holding capacity. A pattern of alternate extremes of
dryness and wetness is detrimental to palm seeds during germination. Particle
size in the medium should not be excessively large nor prone to separation with
repeated irrigation. A 1:1 mixture by volume of peat moss and perlite has been
successfully used under a wide range of nursery conditions. The mix in a
germination medium should be adjusted depending on the conditions to which the
seed will be exposed. For example, seed germinated in full sun will require a
medium with higher water holding capacity than seed germinated under shade, all
other conditions being equal.
Planting
Depth and Spacing
The depth at which palm seed will be
sown varies with size of the seed and the species being grown. More
importantly, environmental conditions dictate depth of planting. If seed will
be germinated in full sun, it is usually necessary to cover the seed with
medium so that it will not dry out. A rule of thumb to follow is to cover the
seed to a level equal to the diameter of the seed. For example, seed 1/4 inch
in diameter would be planted at a depth of 1/4 inch below the surface. However,
if the seed is to be germinated under shade, it is usually better to sow it
shallowly. In the case of larger seeds, this means merely pressing them into
the soil so that the top of the seed is exposed. Frequency of irrigation will
also influence the planting depth. Seed germinated in full sun can be planted
more shallowly if irrigation will be frequent enough so that the medium does
not dry out.
The initial planting density depends on the ultimate use of the germinated
seedlings as well as how quickly the nursery operator anticipates transplanting
the seedlings. Many growers broadcast small (1/4 inch diameter or less) and
medium-sized (1/2 to 1 inch
diameter) palm seed very thickly in the germinating container, in some cases
completely covering the surface of the medium with seed. This works fine (and
saves space and labor) if the transplanted liner will consist of all or a
number of the seedlings potted together (for example, areca palms, Figure 9, and
some Chamaedorea species) or if the seedlings will be separated and
transplanted before a great deal of root development has taken place.
Otherwise, it is best to sow the seed with some space between adjacent seeds.
Large seeds, especially those of difficult to transplant species such as Bismarckia, are
often sown one per container.
Germination Conditions
Figure 9. Areca palm
(Dypsis lutescens) seed sown densely in a 4-inch pot. The germinated
seedlings will be transplanted together to make a dense specimen plant.
Temperature
Virtually all palms require high temperatures for the most
rapid and uniform germination of their seed. Seventy to 100°F is the accepted range,
and 85-95°F
probably yields the best results. Seed of paurotis palm (Acoelorraphe
wrightil) has been reported to germinate best at 92-102°F. with only 11%
germination below 86°F
(Carpenter, 1988a). The native Keys thatch palm (Thrinax morrisii) and silver
palm (Cocothrinax argentata) germinated best at 9 1-97°F, with few seeds
germinating below 77°F
(Carpenter, 1988a; Carpenter & Gilman, 1988). Seed of pindo palm (Butia
capitata) germinated best with 2-3 weeks at 102°F, followed by 86°F for the duration of the
germination period (Carpenter, 1988b). Some research has suggested that
fluctuating temperatures at 12 hour intervals may increase total germination
for certain species (Carpenter, 1987, 1989), but this is not practical for most
growers.
Since palm seeds require high germination temperatures, it is best to sow seed
during the warmer months of the year. If availability of fresh seed makes this
difficult, soil temperatures can be increased by using bottom heat below the
germination containers or by covering the containers with clear plastic.
Placing the containers on a heat-retaining surface can also increase
temperatures by several degrees.
Light
Many palms germinate in the
understory of a forest canopy in their native habitats, even if they eventually
grow up into full sun (royal palm, Roystonea spp., for example). Seedlings of these species can be
germinated in full sun but their leaves may bleach to some extent under those
conditions. Many growers feel that, despite the bleaching, root growth and
overall seedling development are enhanced in full sun. Under shade, seedlings
will generally have a deeper green color. Some species grow best in the shade (Licuala spp.,
for example). Seed of the latter group should be germinated under shade.
Seedlings of such species, if exposed to full sun, usually bleach severely,
burn and may even die. Species native to open habitats show no ill effects when
germinated in full sun. It is generally necessary to adjust seed planting depth
according to the light levels to which the seed will be exposed (see previous section).
Irrigation
Palm seeds require uniform moisture
during the first critical stages of germination when the cotyledonary petiole
(in remote germinators) or button (in adjacent germinators) first emerges from
the seed. Alternating periods of extreme wet and dry during this time period
will usually have deleterious effects on total germination percentages. If the
germination medium does not receive some type of automatic irrigation, it may
be necessary to cover the containers with clear plastic to retain adequate soil
moisture. Over watering can be equally deleterious. At no time should standing
water be visible on the surface of the germinating medium.
Fertilization
Palm seedlings do not require
supplementary fertilization for the first two months after germination. The
endosperm within the seed provides all the nutrition that the seedling needs
during this period. Supplemental fertilization during the first two months not
only wastes fertilizer but can injure the young seedling.
Germination
Time
The rate at which palm seed germinates, the uniformity of
germination, and the percentage of total germination can vary tremendously from
species to species, from seed lots collected from different plants of the same
species, and even from seed lots collected in
different years from the same plant. Seed of Mexican fan palm (Washingtonia robusta) may begin to
germinate in less than 2 weeks, seed of areca palm (Dypsis lutescens) in
3-4 weeks, while seed of parlor palm (Chamaedorea elegans) may not begin
to germinate for several months and then continue sporadically for over a year.
When planting palm seed of species with which one has no previous experience,
or for which no germination information can be found, one should remain patient
as long as the seed appears in good condition. A fairly comprehensive list of
germination data across a wide variety of palm species can be found in Wagner
(1982).
Transplanting the Seedlings
Figure 10. Palm seedlings in the
germination container ready for transplanting.
Figure 11.
Palm
seedlings should not be transplanted more deeply than the point indicated by
arrow.
Palm seedlings
may be transplanted either immediately after germination or after 1-4 leaves
have formed. The objective is to lessen the degree of root disturbance to the
seedlings; thus it is best to transplant before roots begin to circle the
container or roots of adjacent seedlings become entangled (Figure 10).
Transplant in the warmer months of the year, when root growth will be rapid.
Delay transplanting until at least one leaf has appeared. Seedlings will
usually have one long root at the time of first transplanting. Seedlings should
be first transferred from the germination container to a small liner pot that
just accommodates the root system and allows some subsequent root growth. Deep
liner pots with essentially open bottoms are being used by a increasing number
of growers. Palm seedlings benefit from the deeper root run, and long roots
emerging through the bottom opening are "air pruned" and cease growth, thus
significantly eliminating the circling of roots around the inside walls of the
pot. Two strategies are then possible for subsequent transplanting of the
seedlings. They can be shifted successively to slightly larger containers as
they grow (frequent small shifts), or they can be transplanted to larger
containers than their size might seem to warrant (fewer and larger shifts).
Frequent small shifts lessen the chance of loss due to over-watering, but
increase labor costs. Transplanting into large containers lowers labor costs
and provides for more unrestricted root growth, but may promote increased loss
due to root rots when the seedlings are small. Thus, larger, less frequent
shifts will require careful irrigation monitoring while the transplants
establish in the new containers.
Palms are very intolerant of being planted too deeply, regardless of age or
size. For palm seedlings, planting as little as 1/2 inch too deeply can result
in severe production setbacks and ultimately death of the seedlings. Palm
seedlings should be transplanted so that the point on the seedling stem just
above where the root system appears to begin lies at the soil surface (Figure
11). This point is sometimes marked by a noticeable swelling, particularly on
older seedlings. On palms with adjacent germination, it is the point at the
base of the button. Do not sever the connection of the seed to the seedling
palm. If the seed is still attached to the plant by the cotyledonary petiole
(remote germination), drape the seed over the edge of the pot or allow it to
sit on the soil surface.
Some growers prune palm seedling roots when transplanting. This is not
recommended, and usually results in growth setbacks or even death of some of
the seedlings. If the seedling root is longer than the transplant container, it can be allowed to slightly
curve upward or around the inside perimeter of the container. A better solution
is use pots large enough to accommodate the full length of the root. Some palm
species (Bismarckia and Borassus, for example) bury the seedling
axis for some distance below the ground. Seed of these species are usually
planted singly in deep containers. A number of palm growers have found it beneficial
to remove the soil from the container down to the level of the subterranean
stem crown as soon as the first leaf emerges above the soil.
Ideally, newly transplanted seedlings should be placed under light shade
(30-50%) for several weeks, or until new growth is apparent. If this is not
possible, irrigation frequency must be carefully monitored so that the
transplants are not water stressed during establishment. For further
information, see Container Production of Palms.
Vegetative Propagation of Palms
Despite the
overwhelming reliance on seed propagation for palms, there are several methods
of clonal (vegetative) propagation that can be used for a few species.
Division
Clustering palms, that is those that
produce new erect shoots from a common base or system of rhizomes, can be
divided carefully as a means of increasing stock. Species that produce new
shoots at some distance from the parent stems (Rhapis species, for example),
are the most easily divided. Many Chamaedorea species, Areca and other Dypsis
species, and Paurotis palm (Acelorraphe wrightil) are amenable to
this type of propagation. Stock in containers is generally easiest to divide.
For best results in the field or landscape, it is advisable to separate
divisions from the parent plant with a sharp spade in the spring, but leave the
divisions in place until new growth is evident. At that time the divisions can
be carefully lifted, with as much of the root ball as can be managed. Newly
separated divisions are best potted and kept shaded and well-watered until
established (at least 1 year), after which they can situated in the ground.
Air layering
(Marcottage)
A number of Chamaedorea species
produce conspicuous short aerial roots at the stem nodes (leaf scars). These
species can be air layered by applying a swath of moist sphagnum peat moss
around one to several nodes and wrapping the area in aluminum foil. The aerial
roots will grow into the moss. When sufficient root growth has occurred, the
stem can be cut from the parent plant and potted. Newly cut layers should be
kept shaded and well-irrigated until established in their containers.
Offsets
Several date palm species, most notably the commercial date palm, Phoenix
dactylifera, produce offsets or suckers at the base of the trunk. These can
be cut from the parent plant and either planted in containers or planted
directly in the ground. If no roots are present when the suckers are cut, the
leaves should be reduced in number and/or size.
Summary
1. Collect palm seeds from source trees
when the fruit is ripe.
2. Clean palm seed from the fruit immediately upon collection, air-dry it, dust
it with fungicide, and either plant it immediately or store it.
3. Store palm seed dry in sealed plastic bags at temperatures above 65°F. Life in storage will
vary from several weeks to over a year.
4. A 1 to 7 day presoak in water is recommended for palm seeds before planting.
The water should be changed daily. A soak in gibberelic acid (GA3) is not
recommended.
5. Germination containers and media should balance moisture retention and
good drainage. A 1:1 by volume mixture of peat moss and perlite is widely used.
6. If seed will be germinated in full sun, it is usually necessary to cover the
seed with medium so that it will not dry out. However, if the seed is to be
germinated under shade, shallow sowing is best.
7. Palm seeds require high temperatures for best germination. Seventy to 100°F is the accepted range,
and 85-95°F
probably yields the best results.
8. Seed of most palms can be germinated in full sun, though leaves of some
species may bleach slightly. Seed of understory palms are best
germinated in shade.
9. Palm seedlings do not require supplementary fertilization for at least two
months after germination begins.
10. The seed of many palm species requires several months to begin germination,
and the total period of germination may last for over a year.
11. Transplant palm seedlings before the root systems in the germination
container become greatly entangled. It is generally best to wait until at least
one leaf has appeared. Transplanting is best reserved for the warmer months of
the year, when root growth will be rapid.
12. Palms are
very intolerant of being planted too deeply. Transplant palm seedlings so that
the point on the seedling stem where the root system appears to begin lies at
the soil surface.
13. Do not sever the connection of the seed to the seedling palm when
transplanting.
14. Root pruning seedlings when transplanting is not recommended.
Biblioghy
Broschat, T. K. and H. Donselman.
1986. Factors affecting storage and germination of Chrysalidocarpus
lutescens seeds. J. Amer. Soc. Hort. Sci. 111: 872-877.
Broschat, T. K. and H. Donselman. 1987. Effects of fruit maturity, storage,
presoaking, and seed cleaning on germination in three species of palms. J.
Environ. Hort. 5: 6-9.
Broschat, T. K. and H. Donselman. 1988. Palm seed storage and germination
studies. Prin cipes 32:
3-12.
Carpenter, W. J. 1987. Temperature and imbibition effects on seed germination
of Sabal palmetto and Serenoa repens. HortScience 22: 660.
Carpenter, W. J. 1988a. Temperature affects seed germination of four Florida
palm species. HortScience 23: 336-337.
Carpenter, W. J. 1988b. Seed after-ripening and temperature influence Butia
capitata germination. HortScience 23: 702-703.
Carpenter, W. J. 1989. Influence of temperature on germination of Sabal
causiarum seed. Pnncipes
33: 191-194.
Carpenter, W. J. and E. F. Gilman. 1988. Effect of temperature and desiccation
on the germination of Thrinax morrisil. Proc. Fla. State Hort. Soc. 101:
288-290.
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Palm
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1. This document
is BUL274, one of a series of the Environmental Horticulture Department, Florida
Cooperative Extension Service, Institute of Food and Agricultural Sciences,
University of Florida. Original publication date July 12, 1991. Reviewed and
revised June 10, 2004. Visit the EDIS Web Site at http: edis.ifas.ufl.edu.
2. Alan W. Meerow, former palm and tropical ornamentals specialist and
professor, Department of Environmental Horticulture, Ft. Lauderdale Research
and Education Center, Cooperative Extension Service, Institute of Food and
Agricultural Sciences, University of Florida, Ft. Lauderdale, FL 33314.
The
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orientation, marital status, national origin, political opinions or
affiliations. 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! Larry R. Arrington. Interim Dean