M.P.R.R.: The Secret Of Filiferas

Forget so-called ultra hardies that don't grow, and invest in a bale of straw.
Philippe Byrne, Little Brookfield, Pinn Lane, Pinhoe, Exeter, Devon, EX1 3RF, U.K.
Chamaerops No. 12, published online 23-09-2002

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Above: Washingtonia filiferas snug in their winter overcoats of straw. Exposed lea yes may be damaged by frost and cold but will be rapidly replaced during the follo wing spring & summer.
Below: Photographedin late summer, these Washingtonias look perfectly at home in Exeter, Devon.

In 1981 I purchased a couple of hundred seeds of Washington filifera - the Californian or Petticoat palm, from a seedsman in the North Island of New Zealand. They sprouted well and over the ensuing years I sold, gave away and even culled the seedlings until I had only 3 plants left. They were the most vigorous of all, and I treated them well. Every spring I re-potted them into larger pots using a proprietory compost, and then fed them generously during the growing season. In the winter, the greenhouse was kept frost free, but only just!

By the summer of 1990, the 3 filiferas were in medium sized tubs, and competing for greenhouse space with large specimens of Brahea edulis, B. brandegeei B. edulis x brandegeei B armata and 2 Trithrinax acanthocoma. I must admit that at the time I rather looked down on the filiferas when compared with the choice Braheas and Trithrinaces. So I decided to take a risk and plant them outside the Palm house in the lawn, on the basis that they were easily replaced, and therefore expendable. The only soil amendment was to enrich the rather heavy clay soil with some well-rotted cow manure.

When autumn came I decided not to worry about tidiness, but to insulate the trunks with thick wads of straw secured with string, and to pack the crown and emerging leaf with handfuls of straw. One bale (costing £1 delivered) was sufficient for the 3 plants, and the whole operation took a mere 20 minutes.

By late spring, all the leaves that stuck out from the 'mini-haystacks' had gone brown and withered from repeated frost, but when the straw was removed in May, the spear was already growing vigorously, and one beautiful leaf after another began to open in rapid succession, encouraged by liberal feeding and watering. By August the plants had a good head of bright green, healthy leaves, and noticeable thickening of the trunk, but with 2 added benefits: the petioles were much shorter and thicker and the leaves much more filamented or hairier! Uncannily, nest-building birds cottoned on to this as soon as the new leaves started growing, and helped themselves freely!

After coming through a second and third winter protected by straw, I began to appreciate the filiferas more and more. They survived the winter frost so reliably in their thick straw overcoats, and grew new leaves at such an astonishing rate that they must be considered as garden worthy as Trachycarpus fortunei and Chamaerops humilis.

This then is the secret of my filiferas: Minimal Protection - Rapid re-growth. Maybe there are other palms waiting in the wings which will also be shown to thrive in the same way - Parajubaea cocoides perhaps, and almost certainly Phoenix canariensis - but for now, Washingtonia filifera appears to have a unique advantage over other near-hardy palms: the amazingly fast growth, which quickly replaces any winter damage. Compare with Rhapidophyllum, the hardiest palm but producing, in our climate anyway, only one leaf per year.

I would like to emphasise the importance of using straw rather than bubble or plain polythene for winter protection. Although straw gets wet and soggy on the outside, further in it stays dry - and keeps the plant dry. If a layer is placed radially at the base of the trunk with a slight downward pitch, it can even shed rain water (undesirable in the winter) away from the plant and its immediate root area. Secondly, it allows the plant to breathe, and so avoids the chance of rot or fungal attack. Thirdly, it is cheap, readily obtainable, a very good insulator, natural, even attractive in a rather untidy way, and in the spring it can be added to the compost heap! Those gardeners of former times knew a thing or two.

The photographs on the opposite page show the filiferas in April and September of this year. The largest plant is now 5ft tall and growing even stronger and more impressive. The plants look so natural and healthy that they could be native Devon species! As I write, in late November, the 3 filiferas are again safe and cosy in their straw coats (they now require 2 bales). They have taken a hammering from unusually early winter frosts (2 successive nights at -5¾C) and the exposed leaves are already going brown, but I am confident that by next April they will be bursting into growth again.

Other tips to ensure success: Make sure they are planted out in a sunny, preferably south or south-west facing position, perhaps in a corner. Choose a location that's free from wind, and where the soil is free draining, but water frequently especially in hot weather. You will almost be able to watch them grow! Another good idea would be to take up a slab on a sunny patio and plant one there. Think of all that stored and reflected heat!

May Washingtonias filiferate all over southern Britain and beyond!

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