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.

I am a garden book author and horticultural photographer based in Christchurch, New Zealand. I run a stock photo library called Country, Farm and Garden (http://www.cfgphoto.com). This article may be re-published provided this information is published with it and is clearly visible.