A Practical Guide to Germinating Palm Seeds
By Jeff Marcus, Floribunda Palms and Exotics, P.O. Box 635, Mountain View, Hawaii 96771,
Ken Banks, PO. Box 555, Pahoa, Hawaii 96778 USA
Chamaerops No. 51 - published online 22-04-2005
1st: Thrinax radiata
2nd: Phoenix roebelenii
3rd: Pritchardia remota
4th: Pelagodoxa henryana
5th: Medemia argun
6th: Gaussia maya
Photos by Tobias W. Spanner
1st: Phoenix theophrastii
2nd: Wodyetia bifurcata
3rd: Latania loddigesii
4th: Plectocomia himalayana
5th: Roystonea regia
6th: Attalea funifera
7th: Brassiophoenix schumannii
8th: Caryota maxima Himalaya
Photos by Rudolph Spanner
With most palms, propagation from seed is not difficult as long as a few basic requirements
are met. Among the most important are fresh seed, good sanitation, proper medium, proper hydration, and adequate
heat. Each of these points will be discussed separately, although they are inter-related.
The fresher the seeds are, the better the results will be. To check the freshness of your seeds, cut open a
sample seed and inspect the endosperm and embryo. The embryo should be fresh, firm, and not discolored. If the
interior of the seed is rotten or has an unpleasant odor, it is unlikely to germinate. The endosperm is of two
types, homogeneous or ruminate, and may be hard, oily, or even hollow. If the inside of a homogeneous seed is
off-color, such as brown or gray, or if it smells bad, the seed is old or was harvested before maturity. Such
seeds are also unlikely to germinate. In a ruminate seed, the seed coat is infolded, creating dark, tangled
streaks in the endosperm. Ruminate seed is more difficult to assess because of its more complex appearance.
Removing the Fruit Pulp
The fleshy or fibrous fruit pulp frequently contains growth inhibitors. Removing it before planting will improve
results. Methods for doing this vary with the quantity and type of seeds, but most begin with a preliminary
48-72-hour soak in water. Soaking causes the pulp to ferment, which weakens it for easier removal. Change the
water daily during the soak. Fruit that is slightly immature should be placed in a tightly closed plastic bag
and kept in a warm spot for a week or so. This promotes ripening and softens the outer flesh for cleaning. Sometimes
the seeds need to be soaked further to soften the pulp, sometimes not.
There are several ways to remove the seed coat. With small quantities of seeds, simply rub them by hand against
a fine-meshed screen and wash away the pulp with water. Another way that works well with small amounts of seed
is to shake them by hand in a closed container with water and small, rough-edged rocks. Pour off the water and
pulp occasionally, add more water and shake again, until the seeds are completely clean. Seeds can also be cleaned
with a knife or other sharp tool, but this is slow and a little dangerous.
Motorized cleaning devices make the job easier and are a necessity for commercial operations. For smaller quantities,
use a rock tumbler. Put rocks and water inside with the seeds. Larger seed-cleaning machines can be purchased
or fabricated. Some large-scale growers and seed dealers use cement mixers to do the job. The seeds are rotated
in the drum for 10-45 minutes with water and rough-edged rocks of 7-10 cm. The time will vary with the machine
and the type of seed and rocks. Some seeds are brittle, and without proper care may be damaged by power cleaning.
Among large-seeded palms, Actinorhytis is particularly brittle and prone to damage, and many smaller seeds,
such as Pinanga, must also be handled with care. When cleaning seeds, remember that the flesh of some types
contain crystals of calcium oxalate, a skin irritant that can cause severe pain on contact, depending on the
individual's sensitivity. For this reason, Ptychosperma, Arenga, Caryota, and Wallichia should be handled with
Damaging insects such as seed-boring beetles may arrive with seeds. They may reduce germination and spread to
other seed batches. To minimize these risks, seeds collected from the ground, whether in the wild or from cultivated
plants, and seeds collected under unknown conditions should be soaked in a contact insecticide solution once
the fruit pulp has been removed. The insecticide solution should be prepared at the same concentration you would
use to spray for pests. Soak small, thinner-shelled seed, such as Pinanga, for 15 minutes. Soak larger, harder
and less permeable seeds longer, from 20 to 45 minutes. Examples of these latter seeds are Mauritia flexuosa,
Bismarckia nobilis, Parajubaea cocoides, and Jubaea child. After the insecticide soak, rinse the seeds in clean
water for 20 minutes.
After cleaning the seeds, hydrate them by soaking them in water for 24 hours, especially if you did not soak
them to help remove the pulp. Within 24 hours most fresh, viable seeds will sink. There are exceptions such
as Manicaria saccifera and Metroxylon vitiense, whose viable seed will float even after cleaning and soaking.
Whether or not to discard a batch of heavily infested, damaged seeds depends on their rarity and your ability
to get more. For very rare seeds, when even a single germination could be valuable, plant it. Remember, however,
with heavily infested seeds, especially in large quantities, there is the danger of introducing pests into your
nursery. Balance this risk against the desirability of propagating the seeds and follow the treatment procedures
Fungi flourish in the heat and humidity necessary for good germination, so equipment, fixtures, seeds and growing
medium must be kept clean to prevent damping-off and other disease problems. You may want to soak seed in a
fungicide before planting.
Germinate the easy varieties in a commercial mix of peat moss or sterile sphagnum moss mixed with an equal amount
of perlite or vermiculite. You may also use commercially prepared, finely cut coconut coir to which the same
fast-draining material has been added. Sand, wood chips, screened rock or volcanic cinder screened to a maximum
size of 9 mm can substitute for vermiculite or perlite. Whatever you use, the medium should be very porous and
drain extremely well. All containers should have plenty of holes in the bottom to ensure quick and thorough
When containers and planting medium are ready, lay out the seeds on the surface, and before covering them, dust
with a commercial insecticide. Bury the seeds in the medium to a depth of half the seed diameter and then cover
everything with finely screened cinder (3-6 mm particle size), thick enough so it will not wash away during
watering. This top-dressing dries out quickly and discourages the moss that grows on peat. Sand or finely crushed
rock would work just as well. When planting is complete, place the containers on clean benches, 60-90 cm above
the ground. Be sure to label your containers with a waterproof and fade-proof marker.
Palm seeds known as remote germinators may require special treatment and a little extra patience. Remote germinators
push a shoot downwards as much as 20-25 cm before sending up the first leaf (Fig. 1). The larger ones such as
Voanioala and Borassodendron, should be planted in deep containers such as citrus bags or large tubs, or be
transferred to such containers soon after germination. If seeds and seedlings can be protected, the collector
may want to plant large remote-germinators directly in the ground.
Hydration and Heat
At this point, the most important factor in seed germination is proper hydration, followed by constant high
heat. Maintaining proper hydration is the trickiest of the two. Water your containers thoroughly, but just as
important, let them dry out thoroughly before watering again. Over-hydration can drastically reduce the germination
percentage. Once seeds begin to germinate, the containers will require more frequent watering. Seeds should
be kept at 26-35ÉC. Some growers provide constant bottom heat by means of electric pads on their benches.
For difficult seeds and rare seeds, the most reliable method of germination is the Plastic Bag Method. For this
method, seeds are blanketed in damp sphagnum moss and germinated in zipper-type, re-sealable plastic bags. Thoroughly
saturate the sphagnum moss with water and wring it until no more can be expressed. Place the seeds and the sphagnum
moss inside the plastic bags (along with a label) and keep the bags at 26-35ÉC. Check inside the bags periodically
to ensure that the sphagnum has not dried out. Once seeds have germinated, place them in community or individual
pots containing the potting mix described above and the quick-drying top-dressing. When transferring germinating
seeds from the relatively sanitary conditions inside the bags to pots containing ordinary medium, treat them
to a precautionary fungicide drench. Germination setups can also be improvised from plastic foam boxes with
tight fitting lids, such as are used to pack fish or fruit. Fill the boxes 1/3 full of fine perlite pieces and
lay the seeds on top. Use a hand mister to dampen thoroughly the seeds and perlite, replace the lid and place
the box in a warm location. These germination boxes are space-savers, because they can be stacked. The tight-fitting
lids help keep out fungus and insects, but the boxes should be checked periodically for hydration and germination.
A final method (if it can be called a method) is simply to germinate the seed on the ground in an out-of-the-way
part of the greenhouse or garden. Growers have had good results this way with Pelagodoxa henryana, Jubaea chilensis,
and some Acrocomia species. Discarded seed has also been found germinating in many a surprised grower's compost
Reprinted from the Palms, Journal of the International Palm Society, Vol 43, No. 2, Horticultural issue,
April 1999, with permission from the author. www.palms.org.
19-09-21 - 11:05GMT
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