Growing Palms
Palms Everybody recognises palm trees, they are the universal symbol for the tropics
but many are hardy enough for our temperate climate gardens. Until recently New Zealand
gardeners have had only a very limited range of palms to choose from. In the last five years
the range has grown enormously as nurseries have been encouraged by gardeners eager to
experiment.Nevertheless, palms are, on the whole, slightly tender plants. Those that
will tolerate regular frosts of -6°C. or more are few in number. If your minimum temperature
does not drop below -2°C or if you are in a frost free area the range of suitable plants
increases considerably.There are two main styles of palms; the fan and the feather.
The names refer to the layout of the fronds. Fan palms have the leaflets of the frond arranged
just like a hand operated fan. The most widely grown fan palm is Trachycarpus fortunei, the
Chinese Fan Palm. Feather palms have the leaflets of their fronds arranged along a rigid
midrib like a bird's feather. The most commonly grown feather palm is Phoenix canariensis, the
Canary Island Date Palm. Palms are extremely important plants to the world's economy. The true date palm or
commerce, Phoenix dactylifera, is rarely seen in New Zealand but is the most common
commercially grown palm. The coconut, Cocos nucifera, is not far behind. Possibly more
significant than fruit crops is the use of palms for shelter. Virtually every tropical third
world village relies on palms as a roofing material.
Siting Although palms are
associated with sun and sand most species appreciate light shade when young. Shelter from wind
is important if the fronds are to look their best but as the plants eventually become quite
large they will eventually have to tolerate exposure to sun and wind.When siting a
palm remember to take into account the spread of the crown. This is not so significant with a
mature plant as the crown is usually well above most obstructions. The problem is adolescent
plants, which tend to have much the same spread as adults without the height. They take up a
considerable area until the trunk begins to develop.
Soil conditions Palms
generally do best in a rich, moist well-drained soil. They have fairly strong roots that
anchor them firmly. The roots of many palms can withstand a considerable amount of abuse,
which enables the trees to be safely transplanted at almost any size.
Climate
adaptability Many palms are frost tender but there are quite a few that tolerate
reasonably tough frosts. The best known are Phoenix canariensis and Trachycarpus fortunei but
you should also consider Jubaea chilensis, Chamaerops humilis, Butia capitata, Washingtonia
robusta and Brahea armata.
Palms often grow well in coastal conditions but benefit from
occasional wash downs to remove any salt spray deposits.
Container growing Palms often make superb container plants, both indoors and
outdoors. Many are undemanding and tolerant of neglect. In cold areas it's often best to keep
young palms in containers until well established. That way they can be moved under cover for
winter. Once they have a spread of over 1.5 m or so they should be hardy enough to plant out
but if it's not inconvenient it's better to wait as long as possible.
Propagation
Palms are nearly always propagated by seed. They usually have only one growing point so
vegetative propagation is not practical. Occasionally suckers form at the base of established
plants and may be carefully removed for growing on but this is not a reliable method of
propagation.Palm seed varies greatly in its ease of germination. The most common
problem is very hard seed coats. No amount of scarification or soaking will soften the
toughest of them. Sometimes acid treatment is resorted to but patience is the usual method.
Some, such as Butia capitata, may take upwards of a year in the soil before germination but
eventually with the right combination of moisture, temperature and time they sprout.
Pests and diseases Palms are not prone to any unusual pests or diseases. Frost damage
is far more likely to the biggest problem.
Palm selection
Do not expect to
find all of the species at your local garden centre; many of these palms are only available as
seed. Unless otherwise stated all of these palms have panicles of small yellow flowers.
Archontophoenix The King Palm (Archontophoenix alexandrae) is a prominent feature in
many tropical and sub-tropical areas but it is too tender for all but the very far north.
Archontophoenix cunninghamiana is a better bet but it still requires a near frost free climate
with warm summers. It is a feather palm with long arching frond. It can reach 20 m high but
rarely exceeds 7 m in New Zealand gardens. The flowers are followed by masses of small red
berry-like fruit. Archontophoenix cunninghamiana may be grown indoors but it needs high light
and humidity levels. The seeds germinate easily.
Arecastrum-see Syagrus Arenga
Two species of this genera are suitable for growing outdoors in mild areas. Both are
feather palms with broad leaves that have silvery undersides. Arenga pinnata requires near
frost free conditions but Arenga engleri from Taiwan will tolerate infrequent light frosts.
Both species have interesting flowering habits and fruit. Arenga pinnata is monocarpic; it
dies after flowering although it takes at least ten years to reach maturity. Arenga engleri
survives to flower again but the leaf stem beside the flower stalk dies. Both species have
fruit with extremely caustic pulp. Both species are unlikely to exceed 3.5 m high under New
Zealand conditions but Arenga pinnata may reach 18 m high in its native South East Asian
region. Arenga pinnata seed germinates quickly and easily but Arenga engleri is erratic and
may take several months to sprout. Not usually grown indoors.
Blue Palm-see Brahea
Brahea These fan palms are becoming more common in New Zealand gardens. Both of the
common species Mexican Blue Palm (Brahea armata) and Guadeloupe Palm (Brahea edulis), are
reasonably hardy and adaptable plants. B. armata has beautiful, finely divided glaucous
fronds. It is the hardier of the two and will withstand -8°C once established. It has a stocky
trunk for many years but may eventually reach 12 m high. Brahea edulis is tender when young
but withstands -6°C once the trunk is over 10-15 cm diameter. It grows slowly to about 15 m
high. Both species are tolerant of drought and low humidity. Brahea armata has 12 mm diameter
brown fruit, while Brahea edulis has edible 18 mm diameter blackish fruit. Grow in full sun.
The germination of Brahea armata seed is very erratic and may take up to year. Brahea edulis
is less tricky but still not very reliable. High light requirements make Brahea unsuitable for
indoor cultivation.
Butia
The Yatay, Pindo Palm or Jelly Palm (Butia capitata) from Brazil is a hardy feather palm
with long drooping olive to bluish green fronds. It will withstand -10°C once established and
deserves to be more extensively grown. It grows to about 7 m high. The flowers are followed by
yellow to red 25 mm diameter pulpy fruit. Grow in full sun. Seed germination is highly
variable, it is unlikely to take less than two months and may be a year or more. High light
requirements mean this palm is not very suitable for growing indoors.
California palm-
see Washingtonia Canary Island date palm-see Phoenix Caryota The Fishtail
Palm (Caryota mitis) is often grown as a house plant and is unlikely to grow well outdoors
except in the very far north. Caryota urens has slightly lower heat requirements but will not
tolerate any frost. It has very dark green, slightly arching fronds. All Caryota palms have
intricately cut bipinnate feather fronds. Most species grow to large sizes (over 18 m high) in
the tropics but are unlikely to exceed 8 m high under New Zealand conditions. They have fruit
with caustic pulp that should not be handled with bare hands. The seed germinates easily.
Caryota palms grow well indoors but prefer warmth and high humidity.
Chamaerops
The Mediterranean Fan Palm (Chamaerops humilis) is a bushy fan palm that is usually multi-
trunked and will not exceed 6 m high. The trunks take many years to form and are seldom seen
in gardens. Most plants grow to about 1.5 m high x 5 m wide. The fronds are tipped with sharp
spines. It is a very hardy palm that tolerates -15°C. Tolerant of low humidity and drought.
Grow in full sun. The seed germinate well and takes about six weeks to sprout. High light
requirements and sharp spines make it unsuitable for indoor use.
Chilean wine palm-see
Jubaea Chinese fan palm-see Trachycarpus
Cocos The Coconut Palm (Cocos nucifera) is one the most important commercial crops.
It is essentially a tropical palm but will grow outdoors in frost free areas of the far north.
It is a large feather palm that often develops a leaning trunk. It may grow to 30 m high in
the tropics but rarely exceeds 8 m in gardens. The fruit seldom will not develop to its normal
size in our climate but becomes large enough to be a conversation piece. Coconuts germinate
well but take at least three months to sprout. They need consistent warmth and the whole nut
must be planted, do not strip away the husk. May be grown indoors but resents cold draughts.
Date palm-see Phoenix Euterpe Although primarily a tropical plant the
Assai Palm (Euterpe edulis) will grow outdoors in frost free areas with warm summers. It is a
feather palm with arching fronds and graceful drooping leaflets. The trunk is improbably slim
fro the size of the foliage head and may grow to 25 m high although it is unlikely to exceed
10 m high under New Zealand conditions. The fruit is black and about 12 mm diameter. The seeds
germinate easily. May be grown indoors when young.
Fishtail palm-see Caryota
Howea Very popular indoors but capable of growing outdoors in frost free areas, these
palms were formerly classified as Kentia and are still widely known by that name. Two species,
Howea belmoreana and Howea forsterana, are grown. Both are natives of Lord Howe Island. They
are feather palms with deep green gracefully arching fronds and narrow trunks. Howea
belmoreana grows to about 7 m high and Howea forsterana about 15 m high but both are unlikely
to reach these sizes in New Zealand gardens. They have brown olive sized fruit that takes two
years to ripen. Only very fresh seed will germinate and even then it is erratic. Both species
need shade when young, which is why they perform well indoors.
Jubaea
The Chilean Wine Palm (Jubaea chilensis) is a hardy (-8°C) feather palm that should be more
widely grown. It has deep green arching fronds and a very distinctive trunk. The trunk becomes
greatly enlarged, rather like a baobab tree, so that when mature it may be up 2 m diameter.
Within the trunk is a large reserve of sap, which may be tapped and fermented into an
alcoholic drink, hence the name Wine Palm. This palm can grow to 20 m high or more but it
takes many years to get above 10 m high. The 40 mm diameter fruit is yellow and the seed it
contains germinates easily but takes about four months to sprout. May be grown indoors but has
high light requirements.
Kentia-see Howea Lady palm-see Rhapis Livistona
These fan palms are native to South East Asia and Australia. Two species, Livistona
australis and Livistona chinensis, are suitable for growing outdoors in mild areas. They are
very similar to one another. Both have deep green spiny fronds with leaflets that droop and
fray at the tips. They have quite solidly built trunks that grow to about 12-15 m high. Under
New Zealand conditions it takes many years for them to reach 10 m high. Both species are hardy
to about -5°C when well-established. Livistona australis has 18 mm diameter reddish fruit and
Livistona chinensis has 25 mm diameter green fruit. The seed of both species germinates easily
and quickly. May be grown as house plants but they have high light requirements.
Nikau-
see Rhopalostylis Palmetto-see Sabal Phoenix The Canary Island Date Palm
is by far the most common feather palm grown in New Zealand gardens. It has deep green arching
fronds and a trunk studded with bases of old fronds. When young, the trunk tends to be quite
bulbous but as it gains height it becomes more tree-like. A mature tree may be up to 18 m high
and have a very solid trunk. The fruit is about 40 mm diameter and yellowish orange. Phoenix
dactylifera is the true 'Date Palm' of commerce that is such a well-known symbol of North
Africa and the Middle East. It has shorter fronds in a less dense head than Phoenix
canariensis. It is much taller when mature, up to 25 m high. Both Phoenix canariensis and
Phoenix dactylifera will withstand -8°C when established but should not be exposed to hard
frosts until the have a short trunk. Phoenix dactylifera needs hot summers to grow well and is
unlikely to produce edible dates in a cool summer climate.
A third species, the Pygmy Date Palm (Phoenix roebelinii) is considerably less hardy but it
can be grown outdoors in frost free areas. It is frequently used as a container plant as it
only grows to about 3 m high. There are several other species that would be suitable for
growing in New Zealand gardens but they are rarely seen . Among those most likely to do well
are Phoenix loureiri, Phoenix rupicola and Phoenix sylvestris. All Phoenix palm seeds
germinates quickly and easily. All species make excellent house plants when young.
Queen palm-see Syagrus. Rhapidophyllum The Needle Palm (Rhapidophyllum hystrix)
is native to the south eastern United States. It is a hardy fan palm that remains low growing
and bushy. The olive green fronds have sharp spines on the petioles and the tips of the
leaflets are also sharp. It grows into a multi-trunked clump about 1.5 m high x 4 m wide.
Makes a vicious, nearly impenetrable hedge. It is hardy to about -12°C but requires constant
warm summer temperatures to grow well. Has 18 mm long green oval fruit, the seeds from which
germinate erratically. Grow in full sun. Its spines make it unsuitable as a house plant.
Rhapis The Lady palms are multi-trunked fan palms that are hardy to about -3°C when
established but require warm summers to grow well. Two very similar species are grown, Lady
Palm (Rhapis excelsa) and Slender Lady Palm (Rhapis humilis). They have small fronds on fibre
covered bamboo-like canes. They form dense bushy clumps to about 4 m high with foliage to
ground level. Rhapis excelsa has 12 mm diameter green fruit and grows quickly and easily from
seed. Rhapis humilis does not produce seed and may not be a true species. It is grown from
basal suckers. Both species are excellent house plants that tolerate low light levels and
neglect.
Rhopalostylis This genus is most commonly represented in gardens by our
only native palm, the Nikau (Rhopalostylis sapida), but also includes Rhopalostylis baueri,
which is a similar species from Norfolk Island. Sometimes known as Shaving Brush palms because
of the prominent bulge beneath the foliage head both species are elegant feather palms that
grow to about 8 m high under garden conditions although Rhopalostylis baueri can reach 15 m
high or more in the wild. Both species tolerate only light frosts. Rhopalostylis sapida grows
well in cool climates provided they are nearly frost free but Rhopalostylis baueri needs
steady summer warmth. Both species have 18 mm diameter red fruit. Seed germinates reliably but
may take over three months to sprout. Seedlings are slow growing and need shade. Good house
plants when young.
Sabal
The Palmetto palms are native to the southeastern United States and Mexico. They are fan
palms and often have large fronds. Two species are readily available. Sabal minor and Sabal
palmetto. They are among the smaller species: Sabal minor is a bushy, often multi-trunked and
grows to about 3.5 m high while Sabal palmetto is more tree-like but rarely exceeds 7 m high.
S. minor has glaucous fronds. Both species are hardy to about -6°C once established and both
have 12 mm diameter black fruit. The seed germinates quickly and easily. There are several
other species worthy of trying but they are seldom available. Of these Sabal domingensis is
the most distinctive as it can grow to 25 m high. Sabal mexicana and Sabal uresana are also
tree sized. S. uresana has silver grey fronds and is very drought tolerant. These palms have
high light requirements and are unlikely to be good house plants except for conservatories.
Seranoa The Saw Palmetto (Seranoa repens) is bushy fan palm native to Florida. It
grows into a clump about 2.5 m high x 4 m wide, often multi-trunked. The fronds are silvery
grey to glaucous with sharp tipped leaflets. Hardy to about -4°C. Grow in full sun. The fruit
is oval, about 18 mm long and black. The seed germinates well but may take a few months to
sprout. Can also be grown from suckers. High light requirements would probably limit this
species as a house plant.
Syagrus The Queen Palm (Syagrus romanzoffiana [syn.
Arecastrum romanzoffiana]), is frequently seen as a street tree in tropical and sub-tropical
cities. This Brazilian native has very long finely divided arching plumose fronds that move in
the slightest breeze. It has a slender trunk that can reach 18 m high but is unlikely to
exceed 10 m under New Zealand conditions. Hardy to -5°C when mature but needs protection from
frosts until about 1.5 m high with a good crown. Also needs warm summers to grow well. Has
yellow fruit about 25 mm in diameter and 18 mm long seeds that germinate quickly and easily.
It makes a good house plant when young but needs bright light and humidity.
Trachycarpus The Chinese Fan Palm (Trachycarpus fortunei) is probably the hardiest of
the tree-like palms. It will tolerate -12°C from a young age. The fronds are deep green and
quite luxuriant on young plants grown in the shade but they rapidly deteriorate in full sun
and strong wind. The trunk is covered in fibre and the bases of old fronds and may be up to 12
m high. The small 12 mm diameter grape-like fruit is bluish with a grey bloom. The seed
germinates quickly and easily. As this palm prefers shade when young it makes a good house
plant when young. There are other species worth growing, such as the very dwarf Trachycarpus
nanus, but they are seldom available.
Washingtonia These palms are synonymous
with Southern California. They are fan palms with very straight trunks. Two species are grown,
one Californian (Washingtonia filifera) and the other Mexican (Washingtonia robusta).
Washingtonia filifera can grow to 20 m high and is quite stocky. Washingtonia robusta, which
is sometimes called Sky Duster, has a very narrow trunk and may reach 30 m high or more. Under
New Zealand conditions they are slow growing and unlikely to reach such impressive dimensions.
The fronds have long petioles for fan palms. Both species will survive -6°C once established
but need summer heat to grow well. Both have 18 mm diameter fruit that is reddish green when
ripe. Both species appreciate light shade when young. The seed germinates quickly and easily.
May be grown as house plants until too large to remain inside.