Note from the editor
In 1900, William Bateson, later professor of biology at Cambridge University, gave a lecture to the RHS, which was then printed in the Society’s journal. Its importance lay, at least in part, in the fact that this was the first time that the work of Brother Gregor Mendel, the so-called Father of Genetics (an Augustinian friar working in a monastery in Brno, Moravia, in the 1850s and 1860s), had been explained to Britons. Bateson himself was the originator of the term ‘genetics’, to mean the study of heredity, and he did much to further research into genetics in the early years of the 20th century. The Society is justifiably proud that such an important subject should have first seen the light of day under its auspices.
At the same time as Bateson was revealing all this, other horticulturists were reflecting on the many other advances that had occurred in the 19th century, in particular in the design and layout of glasshouses as well as the huge and permanent impact that the growing of tender plants reasonably cheaply had on British gardeners and gardens. It was a self-confident time for horticultural scientists and innovators, as is instanced by a very positive article reproduced here on the benefits of strong poisons such as nicotine used as insecticides. More recent articles on science, such as that by Mary Keen, strike a rather more timid note. Nevertheless, there continues to be some interesting scientific research done by the Society on plants, in particular. In The Garden can be found articles explaning aspects of science either useful to the home gardener or simply interesting in their own right–such as plants that have leaves of different shapes, as botanist Mike Grant reveals.
In this chapter you will also find pieces on the DNA of Welsh wildflowers, the prospects for biodegradable pots, the extraordinary benefits that can be bestowed by medicinal plants–and a possibly fruitful future topic for the scientists, namely does planting by the moon work?
URSULA BUCHAN, editor
Problems of Heredity as a Subject for Horticultural Investigation
An exact determination of the laws of heredity will probably work more change in man’s outlook on the world, and in his power over nature, than any other advance in natural knowledge that can be foreseen.
“It is not a little remarkable that Mendel’s work should have escaped notice, and been so long forgotten”
There is no doubt whatever that these laws can be determined. In comparison with the labour that has been needed for other great discoveries it is even likely that the necessary effort will be small. It is rather remarkable that while in other branches of physiology such great progress has of late been made, our knowledge of the phenomena of heredity has increased but little; though that these phenomena constitute the basis of all evolutionary science and the very central problem of natural history is admitted by all. Nor is this due to the special difficulty of such inquiries so much as to general neglect of the subject.
No one has better opportunities of pursuing such work than horticulturists. They are daily witnesses of the phenomena of heredity. Their success depends also largely on a knowledge of its laws, and obviously every increase in that knowledge is of direct and special importance to them.
The want of systematic study of heredity is due chiefly to misapprehension. It is supposed that such work requires a lifetime. But though for adequate study of the complex phenomena of inheritance long periods of time must be necessary, yet in our present state of deep ignorance almost the outline of the facts, observations carefully planned and faithfully carried out for even a few years may produce results of great value.
These experiments of [Gregor] Mendel’s were carried out on a large scale, his account of them is excellent and complete, and the principles which he was able to deduce from them will certainly play a conspicuous part in all future discussions of evolutionary problems. It is not a little remarkable that Mendel’s work [on crossing varieties of the garden pea, Pisum sativum] should have escaped notice, and been so long forgotten. For the purposes of his experiments Mendel selected seven pairs of characters as follows:
1. Shape of ripe seed
2. Colour of ‘endosperm’ [the word Mendel used for cotyledons]
3. Colour of the seed-skin
4. Shape of seed-pod
5. Colour of unripe pod
6. Shape of inflorescence
7. Length of peduncle [flower-stalk]
Large numbers of crosses were made between Peas differing in respect of each of these pairs of characters. It was found that in each case the offspring of the cross exhibited the character of one of the parents in almost undiminished intensity, and intermediates which could not be at once referred to one or other of the parental forms were not found.
In the case of each pair of characters there is thus one which in the first cross prevails to the exclusion of the other. This prevailing character Mendel calls the dominant character, the other being the recessive character.
That the existence of such ‘dominant’ and ‘recessive’ characters is a frequent phenomenon in cross-breeding, is well known to all who have attended to these subjects.
By self-fertilising the cross-breds Mendel next raised another generation. In this generation were individuals which showed the dominant character, but also individuals which preserved the recessive character. This fact also is known in a good many instances. But Mendel discovered that in this generation the numerical proportion of dominants to recessives is approximately constant, being in fact as three to one. With very considerable regularity these numbers were approached in the case of each of his pairs of characters.
Horticultural Progress during the 19th Century
It is impossible at the close of this century to look back and review from quite the beginning the growth of our profession–the honourable calling of gardening. We have not the time. The work would be enormous. We must content ourselves with glancing back a hundred years, and noting the changes wrought in our profession during that time. I sometimes think we do not always sufficiently value our privileges and the ancient establishment of our craft. Gardening is undoubtedly the oldest existing profession. We are told that in the very earliest days ‘God planted a garden’, and placed our first forefather there as gardener. Truly it was only a single-handed place to begin with, but what a start was then made! It was the commencement of the most delightful and engrossing of the occupations ever given to man. Medicine and law, while being of ancient origin, cannot claim quite the same antiquity as gardening.
“What a revolution the greenhouse has wrought in our land!”
I shall not, however, attempt to do more than refer very briefly to some of the more important changes which have taken place in connection with horticulture during the century just come to a close, which has probably been the most progressive century from every point of view since the foundation of the world. And I think that in the enormous increase in recent years of the devotees of the Goddess ‘Flora’ we have an overwhelming evidence of the intellectual advancement of our times.
What a revolution the greenhouse has wrought in our land! When I read that one firm of renowned market growers possesses 130 acres of glasshouses!–why, if our grandfathers could see those enormous areas covered with glass they would hardly credit their senses that such a revolution could have taken place in a century. Beyond a doubt a great impetus in the erection of these miles of glass has been the adaptation of heating by means of hot-water pipes, a plan unknown to our grandfathers, which has worked a veritable revolution in many of our methods of gardening. We smile now when some dear old gardener tells us of the watchful care and terribly hard work expended on growing and forcing fruit or flowers when the only known means of heating the houses was by diverting the flue all round the house before it was allowed to enter the upright of the chimney. We wonder how it ever was done, and we hardly realise the transformation now when the merest amateur can have his tiny greenhouse heated by an up-to-date method of hot-water pipes, easily fixed, in a manner which fifty or sixty years ago the gardener of the king could not command.
A marked feature, attributable to the improvements in glasshouses, has been the great multiplication of the kinds of plants grown in them: Orchids, for instance. At the commencement of this century the places where these royal plants were cultivated could be counted on the fingers of one hand, and now every year millions are imported and sold. Market growers have houses full of each variety, and many of quite the most beautiful are to be had at a price paid by our fathers for bedding plants. The stimulus given to the growth of all choice exotics, as Crotons, Dracaenas, Palms, and the all the many beautiful tropical plants, can be traced to the same cause. Nor has the advantage of these improvements been only to the benefit of the wealthy, for the universal extension of glasshouses has had the supremely beneficial effect of bringing many real luxuries within the reach of the poorer classes; for example, Grapes, which years ago were sold at 10s. to 15s. a lb., and can now be had at a tenth of that price, and both early and late in the season.
We have in quite recent years called nature in to our aid in another very opposite form to hot water; I mean the refrigerating process, whereby the growth of vegetation is arrested; and the gardener has now only to pass the plant from the refrigerator to the forcing pit and ‘Ah, presto!’ it is in bloom; be it Lily of the Valley in summer, or Lilium in February, it is all the same.
Nicotine: Its Use and Value in Horticulture
Nicotine is an alkaloid, which occurs in various parts of the Tobacco plant. The compound owes its name to one Jean Nicot, a Frenchman, who first introduced the seeds of the Tobacco plant into France in the year 1560. Nicotine when pure is a colourless compound of an oily nature, but readily soluble in water. It has rather a sickly smell, not at all like the odour we usually associate with Tobacco. It acts upon all animal life as an extremely powerful poison; it is the strongest insecticide known to the scientific world that can be used with safety in checking the ravages of blight and other insects that are injurious to vegetable life.
“Prejudice cannot stop scientific and economic progress; prejudice only recoils upon the people who indulge in it”
In studying the chemistry of insecticides and their relation to plant life one is bound to come to the conclusion that nicotine is the compound amongst all others that can be used by the horticulturist with perfect confidence and success. It is absolutely harmless to all forms of vegetable life if used under proper conditions, and if used under these conditions it will not injure or impair vegetable life, but will prolong and strengthen it.
There are three ways of using the compound.
First, by the application of heat, and so vaporising the nicotine, and bringing the vapour into contact with the plants requiring treatment.
Second, by direct application in a liquid form to the plant.
Third, by mixing the nicotine with a combustible fibrous medium and burning it or by burning dried Tobacco leaf, which is practically the same thing.
The first and second methods of using nicotine are reasonable and scientific, and are strongly recommended to give satisfactory results The third method is clumsy, unreliable, and by no means unlikely to cause injury to plant life.
I regret to say that even today in England there are many horticulturists prejudiced against the use of nicotine; but as time goes on, and they see the splendid results obtained by its use, their number is rapidly decreasing. Prejudice cannot stop scientific and economic progress; prejudice only recoils upon the people who indulge in it. In nicotine the horticulturist has a means ready to hand with which he can successfully fight against the ravages of blight in his glasshouses, only let him see to it that the compound is used properly. Abolish all rule-of-thumb methods. My own short experience has taught me that rule-of-thumb methods are useless in practical work. We must be in either an experimental stage or a practical stage, and we may be quite sure that the old truism still holds good–practice makes perfect. I am glad to say that strong efforts are being made to alter the law relating to the sale of poisons for horticultural purposes, and it is to be hoped that at no very distant date it will be possible to obtain nicotine from any respectable nurseryman or seedsman.
Tidying Up our Science
Here we are in the age of science and, with the announcement of a push ‘to create a world-class scientific research centre for the benefit of all gardeners and the environment’, our own RHS is about to become a major player. And here I am, like (I suspect) many members of a certain age, grappling with ‘why science matters’.
“I am a completely unscientific gardener of the muck, mystery and ask-everyone-else school of gardening”
British writer C P Snow (1905–1980) spoke in the 1960s of ‘the Two Cultures’, that ‘incomprehension tinged with hostility’ towards science once attributed to intellectuals educated only in the humanities. These days, society may have moved on, but many of my generation remain puzzled by science. We just don’t get it.
I am a completely unscientific gardener of the muck, mystery and ask-everyone-else school of gardening. So I went to RHS Garden Wisley to talk about my shortcomings with Roger Williams, [then] RHS Head of Science.
Roger was patient and I came away with a better idea of why the RHS needs to lead research for gardeners. In the wider world, Roger says, there is plenty of work being done into the genetic code and other important topics, but it leaves less time and money for horticultural research. Research at the Royal Botanic Gardens, Kew is more slanted towards wild plants than cultivated ones. Government cuts mean that many universities have had to reduce research budgets (some, like Reading, send several PhD students to work at Wisley).
Roger believes it is important for his team to engage in areas of biological science that can deliver the answers gardeners like us need. These include taxonomy, of course, even though non-scientists moan that plant names change too often. Roger says firmly that we would be ‘in a big of a mess if we didn’t know exactly what was what’. (Clearly scientists have tidier minds than most of us.)
Managing resources, particularly water, is increasingly vital. As water becomes scarcer, will we frown on neighbours who use it for hanging baskets rather than for crops? And can we be encouraged to find other ways of saving water? The new RHS science labs will teach everyone how to cope with the ever-shifting target that is climate change.
Scientists need to be a step ahead of what is happening to biodiversity and natural resources, so that they can help the rest of us to manage the problems that face us now. These are issues that were not around in C P Snow’s time, let alone when the Wisley labs were built in 1907.
City gardens are high on Roger’s research list. Gardens tend to be given over to extensions or offices for people to work from home, but keeping the city green matters more than ever. A quarter of London’s land is occupied by gardens–which can support wildlife, help to cool the area or mitigate the flood risk that comes with freaky weather brought by climate change. I asked about green walls, but Roger says green roofs are probably a simpler way of delivering environmental benefits in built-up places.
The current flux in the natural world is worrying. After my trip to Wisley I felt more confident that, in the capable scientific hands of the RHS, all gardeners would be better prepared to cope with change.
Plant Science Questions for the Curious
WHO DISPERSES MY FRUIT?
Colourful, juicy, tasty fruits have evolved their colour, juiciness and flavour in order to appeal to creatures that eat them and hence naturally disperse the seeds.
“Avocado, native to Mexico, may have been naturally dispersed by giant ground sloths”
With cultivated fruits, humans have taken control to become the fruit thieves, and we try to fend off secondary thieves. Birds are our biggest competitor, taking small red fruits such as cherries and raspberries. Fortunately in Britain we don’t have to contend with fiercer creatures, such as bears, that disperse larger fruits like apples in nature.
Some fruits no longer have living natural dispersing species, which has led to fascinating speculation as to what those creatures, now extinct, might have been.
Avocado, native to Mexico, may have been naturally dispersed by giant ground sloths. Osage orange (Maclura pomifera, inedible to humans) is native to Texas, USA and has no effective natural dispersers, not even deer. But the ease with which the seed germinates from domesticated horse dung suggests it was dispersed by Pleistocene horses, and possibly even mastodons and mammoths.
PLANT CHILLING REQUIREMENTS
February is usually one of the coldest months. It is therefore an important time of year for plants that require winter chilling. Spring-flowering bulbs such as daffodils, hyacinths and some tulips typically require a period of winter cold in order to flower successfully.
“…even hops need specific amounts of winter chilling to flower and fruit productively”
Other plants for which winter chilling is important are fruit trees and bushes. In the UK, apples, pears, cherries, blackcurrant, plums and even hops need specific amounts of winter chilling to flower and fruit productively.
Growth inhibitors accumulate in flower and leaf buds when they are formed during the summer and autumn, and these prevent the buds opening during winter. The chilling is required to break down these growth inhibitors and ensure the buds open at the right time. Each cultivar needs a specific number of ‘chill hours’ below a certain temperature–usually given as 7.2°c (45°F) in the UK–to break dormancy, and the number of hours required can range from 200 to 1,500.
If plants get insufficient chilling they may suffer from delayed or uneven flowering and leafing, leading to poor crops. Inevitably, climate change has an impact, so warmer winters mean breeders are trying to select cultivars that have reduced chilling requirements.
SHAPE SHIFTERS
Holly and ivy converge at Christmas in a decorative way. Apart from being evergreen, there is little to connect them–they are not related botanically.
“Dimorphism can be seen in many plants”
But they do have a biological feature in common, namely ‘dimorphic leaves’. This is where the leaves of the same species exhibit two different shapes.
Ivy is one of the best-known examples: climbing stems have leaves that are lobed, while those on non-clinging, flower-bearing, aerial stems, produced when ivy reaches the top of its support, are barely lobed at all. The modified shape probably enables leaves to gather light more efficiently.
Holly performs a similar trick, but it is only noticeable on tree-sized specimens, tall enough to be out of the reach of grazing animals. And that is the clue; leaves from holly shrubs or lower tree branches are spiny to avoid being eaten, but those higher up can dispense with spines.
Dimorphism can be seen in many plants. Conifers such as juniper have needle-like juvenile leaves (again, for protection) and adult leaves that are scale shaped. Some water plants have linear submerged leaves to reduce drag in flowing water, but circular floating leaves to support flowers.
Pots for the Future
Like death and taxes, plant pots are always with us. Who has not got a stack of once-used pots left over after their last planting or bedding-out session, perhaps even a tower or two at the back of the shed, just in case they come in handy?
But even plastic pots have a limited useful life, not least because they tend to become brittle over time. At some point they have to be disposed of but we are running out of landfill sites. An estimated 500 million plastic pots are in circulation in the EU (11 million a year are sold in the UK alone, according to one leading manufacturer). The polypropylene of which they are made takes thousands of years to degrade, so are there more environmentally responsible options?
The Garden Industry Manufacturers’ Association points out that modern plastic pots can contain as much as 70 percent recycled plastic, and many are made in the UK, two factors that reduce both their carbon footprint and their impact as waste. Some local authorities will accept them for their plastics recycling schemes.
The alternative is a fully biodegradable pot–it will break down in the ground if it is left on the plant or it can be composted. But that is not a new idea. Paper, peat and ‘whalehide’ pots have been around for years, invented to protect young plants’ roots at transplanting. But there is now an increasing drive to produce pots that behave like plastic on the nursery or in your glasshouse at home, but which will degrade quickly when you want to throw them away.
“Biological materials now used for pots include rice husk and miscanthus waste that has been compressed and bonded…”
The balance between keeping the material stable during its useful life and fast degradation after disposal is a huge challenge. So, too, is making a degradable pot that performs as well as plastic when it is being handled on the nursery. Biological materials now used for pots include rice husk and miscanthus waste that has been compressed and bonded, and plastics derived from vegetable starches. One supplier has introduced what looks like the best of both worlds–a plastic pot that contains an additive that makes it break down to water and organic matter within five years (but only under controlled composting conditions).
It is not only gardeners who want choice in the type of pots they can buy. Many nurseries are looking at using biodegradable pots of various kinds. Unfortunately the additional cost, either of the pots (which can be four times that of plastic) or having to change their handling systems, can be a barrier.
For one Hampshire nursery though, their changeover to a biodegradable pot has opened up a new niche market. After initial tests in 2006, Kirton Farm Nurseries’ half-a-million plant output is now grown in Hairy Pots, despite the extra production and handling costs. The nursery finds its customers, at least, are happy to pay the extra 30p or so for a ‘greener’ product.
DNA First for Welsh Scientists
Wales has become the first country in the world to map the DNA of all its native plants, using technology known as barcoding. Plant barcodes are useful in a number of fields, from biodiversity surveys to forensic science.
“…all plants native to Wales can be identified from fragments as tiny as a single grain of pollen”
The team of scientists, led by the National Botanic Garden of Wales, spent three years collecting samples of all 1,143 species of native flowering plants before sequencing a section of DNA code from each one.
The barcodes create a catalogue of unique gene sequences, precisely identifying each species and allowing unknown genetic material to be compared for possible matches.
This means that all plants native to Wales can be identified from fragments as tiny as a single grain of pollen.
‘It’s a new take on identifying and classifying plants,’ says project leader Natasha de Vere.
The team’s next step is to liaise with other botanic gardens to barcode the remaining 364 native UK species.
The Hidden Power of Plants
Mankind has used extracts of poisonous plants for millennia, for hunting, hallucination and homicide. However, while we should appreciate the dangers of poisonous plants, we must also be aware that their powerful physiological effects make them important in the development of new drugs. An example is the arrow-tip poison, curare, which is a potent paralysing agent that can lead to rapid death by asphyxiation. The Southern American Indians prepared this poison from dried extracts of Chondrodendron tomentosum mixed with Strychnos toxifera. The active constituent of curare – tubocurarine–is still sometimes used as a muscle relaxant under anaesthetic.
“Catharanthus roseus (Madagascar periwinkle) was once just thought of as an insignificant tropical weed”
New and exciting times in the treatment of human disease have dawned with recent discoveries of novel pharmaceuticals from plants. Scientists have begun to realise that this invaluable source of potential drugs, when coupled with an intimate knowledge of the workings of the cell, august well for the rational design of new therapies. This article concentrates on four very different plants, linked only by the fact that each makes a ‘spindle-poison’.
All living organisms are built from cells–the smallest units of life. Cell structure varies between plants and animals but all cells are essentially chemical factories that import raw materials, and manufacture materials for export. In plant and animal cells chromosomes within the nucleus contain all the genetic information, within DNA, needed to produce a new individual. During cell division the orderly partitioning of this DNA gives two identical daughter cells, each with a complete set of chromosomes, and the process is called mitosis. The formation and degeneration of the spindle–strands of protein which stretch from the poles to the equator of the cell during mitosis and which push the poles apart so letting the cells divide–are both crucial stages. Cell division can be stopped by interfering with either event.
Anti-cancer drugs
Cell growth is exquisitely controlled in a healthy person. When control is lost, rapid and unrestrained cell growth occurs, so many cancer treatments aim to destroy these rapidly dividing cells. Plants can provide drugs either to prevent spindle formation or to stop the spindle dividing into the daughter chromosomes. Some spindle-poisons are too toxic for clinical use but they can provide a basis for the design of new drugs.
Further possibilities arise from the chemical elaboration of any of these substances. So which plants make spindle-poisons and how can they be employed to combat cancer?
Catharanthus roseus (Madagascar periwinkle) was once just thought of as an insignificant tropical weed. Yet in the 1950s it was discovered that this plant produces two of the most valuable and effective drugs in the fight against childhood cancer. C. roseus produces the potent spindle-poisons vincristine and vinblastine. These drugs are especially effective against lymphoblastic leukaemia, a major childhood cancer, and are used in the treatment of Hodgkin’s disease and to treat testicular cancer.
C. roseus is farmed in Texas, USA, and 8,000kg (17,600lb) of flowers are processed every year. Total chemical synthesis of the drugs in the laboratory is possible but it is protracted and difficult, and tissue-culture has met with only limited success.
The useful but poisonous nature of yew [Taxus baccata] has long been known. Caesar records that the Gaelic chieftain Cativolcus committed suicide by drinking an infusion of yew bark after the defeat of his armies by the Romans. Indigenous North American tribes used T. brevifolia (Pacific yew) bark to treat skin cancer and as an abortifacient and disinfectant.
In 1979 biological tests on Pacific yew bark revealed the presence of a potent spindle-poison, taxol, which stops cell division by preventing the spindle from dividing into the daughter chromosomes. Taxol is now invaluable in the treatment of ovarian cancer, but yew bark yields only small quantities of taxol; a 60-year-old tree gives enough taxol to treat just one patient. Pacific yew plantations have been established in the USA, but this is a long-term project.
The chemical structure of taxol is very complex; its laboratory synthesis is too complicated to be used commercially. However, it was noticed that although clippings of T. baccata contain only minute amounts of taxol, they also contain a considerable amount of a related substance called baccatin III. This can be elaborated in the laboratory to make either either taxol itself or the closely related unnatural drug taxotere.
The therapeutic value of taxol has led to considerable effort being put into making the active ingredient using yew grown in tissue-culture; the process should be commercially viable in the next few years.
Colchicum autumnale, although often called autumn crocus, is not, in fact, related to true crocus, despite its appearance. Its powerful effects have long been known; it was employed by Arab and Byzantine physicians, and the Romans to treat gout. It was administered widely in the 18th century in Europe, although the main effective agent, colchicine, was not isolated until 1820. Colchicine is used in plant breeding, for example to double the usual two sets of chromosomes (diploid) to give four sets (tetraploid), which can lead to plants with larger flowers.
Colchicine is too toxic for widespread clinical use, but it is an invaluable research tool. It is a spindle-poison which prevents the splitting of the spindle to form the nuclei of the two daughter cells.
Extracts of leaves, seeds, roots and flowers have been prepared for medicinal use for millennia but the move to identify the ‘active principle’ of individual plants and use specific drugs came only in the 19th century. With the advent of effective purification methods and an appreciation of chemical synthesis we have moved from plant extracts to clinical pills.
Whether a drug is extracted from the whole plant or synthesised in a laboratory depends on the plant’s availability, and the comparative costs of extraction versus synthesis. Sometimes a ‘semi-synthetic’ process is more efficient–when a plant product is further elaborated in the laboratory, as in the preparation of taxol and taxotere from yew. Such semi-synthetic routes can be used to develop new drugs, which are even better than the original.
Two exciting areas of research in the use of plants as pharmaceutical factories have recently become important: tissue-culture, and plant gene engineering or ‘molecular’ farming.
Plant tissue-culture and micropropagation are terms used to describe a range of sterile methods used to grow whole plants from individual cells or from pieces of tissue, such as apical meristems.
Tissue-culture can produce many types of useful compounds but not necessarily the same compounds as the adult plant. Tissue-culture of Catharanthus roseus has not produced any of the valuable vincristine or vinblastine. Intriguingly, although ginseng can be produced by root tissue-culture of Panax ginseng, commercial ginseng dealers do not want the laboratory product; the appeal of whole ginseng roots lies in the desirable shapes! So, the large-scale production of pharmaceutical products by cell culture looks promising, though there are few examples of commercial production yet.
Plant gene engineering gives us the ability to endow a new trait into certain plants by the insertion of a foreign gene. This means that, in the future, we could harvest and purify drugs from easily grown plants, which would not normally produce the compounds.
Most of the world’s population depends on plants as a primary source of health care. Even in the most developed countries many new and modern drugs come directly or indirectly from plant extracts. Indeed, about a quarter of prescription drugs contain compounds either directly derived or modelled from natural plant products. Yet few of the world’s well-known 250,000 plant species have been fully screened for their medicinal effects; in 1988 only about 20 pure chemical compounds from plants were used in clinical practice and these came from just 90 plant species. Much remains to be discovered and it is therefore of paramount importance to maintain the diversity of the world’s flora as well as protecting and recording the wealth of knowledge of different cultures regarding the use of medicinal plants.
Does Planting by the Moon Work?
Since the ancients peered from their caves at the constellations to mark the passage of time, man has believed that the moon exerts a profound influence on the earth. In the 4th century BC, Pytheas, a Greek geographer and explorer, was the first to record that tides were influenced by the moon.
In the 1920s, Austrian philosopher Rudolf Steiner proposed his theories on biodynamic agriculture, including the idea that the moon, just as it affects tides, has an effect on water in people, plants or wherever it may be. This was developed in a series of sowing and harvesting experiments by Maria Thun in the 1950s and further summarised in a paper by Nicholas Kollerstrom and Gerhard Staudenmaier in 2001.
“Those who believe in planting by the moon have a gut feeling that it just might be true. Yet the science is lacking to support their claim”
Devotees, such as HRH The Prince of Wales and John Harris, Head Gardener at Tresillian House, Cornwall, claim that sowing vegetables that crop above ground during a waxing moon, and root crops as the moon wanes, produces better, healthier crops and is part of an environmentally friendly treatment of the earth. For others, however, this is lunacy. In the 21st century we demand hard evidence. Yet statistical analysis suggests that the moon is also responsible for such diverse events as starting fights in pubs and successful depilatory waxing. So why not sowing by the moon?
Things instinctive or spiritual cannot always be explained–as anyone who has seen a ghost or has fallen in love will tell you. Those who believe in planting by the moon have a gut feeling that it just might be true. Yet the science is lacking to support their claim. Those gardeners who need facts to support their practice simply argue, ‘How can the world be influenced by a ball of cheese?’
