Seasonal Palm Growing

Nicolas Cock's experiences, trials, hopes and dreams about growing hardy palms.
by Nicolas Cock, Essex, UK
Chamaerops No.38, Spring Edition 2000

Geonoma weberbaueri, at 2700m in Ecuador.

Palms in the winter

It’s been almost 3 years now since I was „bitten by the bug“ and took the first step of purchasing my first palm, a Dypsis Lutescens, which was summarily executed due to my lack of experience. I have, however, bounced back since those dark days and can now happily boast almost 100 palms in my collection, of every conceivable shape and size. It was about a year before I found out that there were mad men and women out there growing palms in their gardens, even over the winter. I decided to investigate further, which leads me to where I am today. I have developed the obsession of leaving these poor defenceless plants to the mercy of the weather and carefully recording exactly what effect our winter climate has on them, sometimes with unexpected results.

To start with I was dubious about leaving any palms in the garden—going out and spending a few hundred pounds on plants just to see them zapped into oblivion was not exactly my idea of enjoyable gardening—but once the palmophile comes out in you, you begin to notice palms that have been growing in your neighbourhood, right under your nose, many of them years old, and so I thought to myself, why not? I live in Southend on sea (South Essex riviera!!!) where I personally believe we have the best that the weather has to offer, especially when it comes to palm growing. Our yearly precipitation is the lowest in the UK, we have some of the highest summer temperatures, and winter temperatures don’t drop too low. This past winter saw an absolute low of -4°C, and we only had to suffer a few nights of below 0 temperatures. Granted we don’t get the full effect of the Gulf Stream that the South West gets, but, no offence to its people, it’s too wet there! I feel the River Thames helps keep temperatures a degree or so higher, so I’m in no rush to move.

Although still a „beginner“ by a lot of people’s accounts, I’ve learned a tremendous amount over the last couple of years. The question of cold hardiness in palms is one of the subjects that fascinates me the most. The internet and various magazines are crammed full of information regarding hardiness and growing zones that our American cousins seem to covet so much, but I think here in the UK and Europe we have to look at things a different way. Technically where I live is situated in Zone 9 (which means a minimum winter temperature of -1 to -6°C), and being that -5°C is usually our absolute minimum, we feel that we can firmly place ourselves in that zone. However, compare that to another Zone 9 area such as Central and most of Southern Florida, and it doesn’t take an expert to work out that there is no comparison when it comes to climate. Although Florida can get several degrees of frost overnight, this is usually followed by day temperatures of 15-20°C; in other words, back to the conditions palms are used to growing in.

Here in the UK we have to put up with 3-4 months of dull, cloudy days where the temperature rarely rises above 10°C and night temperatures usually fall to a few degrees above freezing. This leads me to believe that a palm’s hardiness should be assessed by whether it can survive a British/European winter or not, and not purely by the figure of a minimum temperature.

I have lost many small palms due, I believe, to the lack of any real heat. I have a polytunnel where I try to prevent temperatures dropping more than a couple of degrees below 0, and a small greenhouse, where I keep my more tender palms frost free, though even here losses have been high. Although it can be disheartening to have these losses, I believe that I have learned a lot by experimenting in this way. For instance, I’ve learned that seed provenance can play a big part when trying new species. I have tried out many Copernicia seedlings this year, species including C. alba and C. prunifera, many of which have succumbed to the low winter temperatures. However, I managed to obtain seed of Copernica macroglossa from the US from a parent that gets a regular frosting, sometimes as low as -7°C!!! Needless to say, I haven’t lost a single seedling (yet) and I’ve allowed them to get frosted to -2°C. Watering is another area that needs to be observed as well. I tend to keep my palms very dry during the winter and water with a fungicide solution about once a month just to keep any root rot in check; it’s amazing how a little moisture and cold temperatures can rot some palm roots in no time.

Other palms that have taken -2°C with little or no damage include Wallichia disticha and densiflora, Wodyetia bifurcata, Parajubaea cocoides, Dypsis decipiens, and Chamaedoria seifrizii and C. oblongata. Happily the garden and unprotected old favourites are doing well. Phoenix canariensis, Rhapis excelsa, Brahea armata, Brahea edulis, Trithrinax acanthocoma, and Washingtonia robusta and filifera have all come through our lowest night of -4°C so far without being scathed, although Livistona chinensis suffered slight tip burn. I was also shocked to find that same following morning that my heater had failed in the polytunnel. There was ice everywhere, which was soon defrosted by the fiery language that followed, of which I couldn’t possibly repeat in a family magazine like this one. Ravenea rivularis and Coccothrinax barbadensis had been totally destroyed, with most of the leaves being lost to the low temperature. However, I think they will recover as the new spears seem to have remained intact. Howea forsteriana had suffered about 20% tip burn. It took me the following weekend to sift through the debris, but to my surprise I didn’t lose a single palm, and a few weeks later, they still seem to be alive. All the other palms have come through OK. Caryota himalaya is actually growing, if very slowly; Syagrus romanzoffiana and Livistona Saribus look great, although they did sustain some damage; Phoenix roebelenii and P. theophrasti are untouched; as are Rhopalostylis sapida, Chamaedorea microspadix and C. radicalis, and an X Butiagrus hybrid.

Like most of you I long for spring and the return of warmer weather, watching as our beloved palms spring back into life, rewarding us with the new growth that we seem to have waited half a year for. But, call me mad, in a way I am looking forward to next winter so I can begin my experimentation process again! I’m looking forward to trying some of the Andean rain forest palms, such as the high altitude Ceroxylon varieties and some more unknown forms of Chamaedorea. Indeed there are quite a few species that look promising, such as Geonoma weberbaueri and jussieiana, found growing at elevations of over 3000m up in the Andean mountains where it is cool and cloudy for a good part of the year. Also worth trying are some varieties of Attalea, Allagoptera, and Acrocomia that come from various other locations in South America. Hedyscepe canterburyana and Lepidorrhachis mooreana from Lord Howe Island also seem to have a lot of promise. If I manage to obtain these palms, I will keep you posted on the results.


Palms in the summer

I personally think seed propagation is great when it comes to growing palms, and late winter/early spring is a time when I like to really get going sowing all those new palms seeds you just seem to keep acquiring. I’ve almost perfected the art of palm seed propagating (well I got there eventually), but there are a few rules to follow that you may well know. For those of you who don’t, the most important rule of all is to buy fresh seed. The best sources are usually suppliers that sell them in bulk, or give an availability period, as they are more aware of the loss of viability in palm seed thus only keeping fresh stock at the times of year that they are available. Second, forget the myth that palm seed is impossible to germinate; about 95% of palm species will sprout without any problem at all. Personally I favour the sphagnum moss method: soak the seeds for a day or two in clean water, changing it every now and then (to remove any inhibitors) and checking that any old fruit flesh has been removed. Then take a zip bag, and half fill it with moss that has been soaked in water and then squeezed out (a rolling pin works well here), and don’t forget to“fluff“ the moss back up before putting it in the bag. Once this is done, place the seeds in the bag and put them in a warm place (between 30-35°C).

I actually have a daylight lamp in my germinating cupboard as well, which prevents any seeds that come up from getting elongated. I usually check the seeds about once a week. If the moss starts to feel a bit dry, I just tip the lot out (carefully!!!) and re-moisten it.

I’ve found that 4-6 weeks is the usual incubation time, although some do take longer. These include Attalea, Acrocomia, Jubaea, and Allogoptera, which can take anything up to 2 years, although so far I have managed to get at least one of each to germinate in less than 6 months. Phoenix, Washingtonia, and Copernica seeds are about the easiest seeds I have ever germinated; they usually taking less than 4 weeks. Trachycarpus and Jubaea can be germinated in the same way although I would recommend a temperature of around 20-25°C, as they seem to germinate better. The only seeds I would recommend sowing in a soil based compost are those seeds that grow long tap roots, such as Borassus and Bismarckia. These need a deep root run into the soil, but can be fooled into thinking that the roots are deeper than what they actually are. The growers in the US actually use a process of raising Borassus seeds by growing them in pots about 18" deep. The tap root will eventually hit the bottom and form a „blob.“ The pot is then carefully knocked out, the seed and root are repotted with the blob just below the surface, and the seed is allowed to hang free attached to a frame or some other kind of support. The first leaf will then emerge from just below the surface allowing the root to grow down another 18". I have used this technique with some success, although the roots do tend to rot easily. However, damage to the tap root is not terminal as long as the seedling has developed some fine roots.
Bismarkia is similar in some respects and can be risen up, though they only require a root run of about 12" in the initial stages.

Living in our part of the world isn’t such a bad thing. There are days when my enthusiasm subsides, but for the most part I’m always kept going by the fact that there is so much to learn and there are so many palms to try. The way global warming is coming along, in years to come maybe many of us won’t have to worry about hard frosts threatening our prize palms. Who knows, maybe our part of the planet will become a flowering tropical oasis. But as for me, I can’t wait that long. Experimentation is part of the fun, and as they say, „If you never try, you will never know.“


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