‘Hardy Woody Plants from Seed’ (Grower Books, 1979) dealt with this subject matter in the context of that time and particularly it reflected the level of practically applicable knowledge and the technology which was available. Horticultural and scientific knowledge, as well as the almost ubiquitous electronic distribution and retrieval of information, have moved on since that time and the sophistication of the techniques used in the nursery industry has developed considerably – however it is still often difficult to locate and then be able to interpret useful information for the seedling production of a particular woody plant and indeed to know whether the detail actually exists and in an accessible form.

 

The development and assembly of those notes (during the mid 1970s) had been prompted by the volatility of European exchange rates at that time; this had created a lack of reliability in the normal pattern of the European marketing of nursery stock. This meant that supplies of seedling material became unreliable both in quantity and quality as stock was diverted, by the producers, to more financially lucrative markets. Reliability of supply therefore would be fostered by the encouragement of a home grown production. Because this industry was virtually non-existent at that time in the UK (except for one or two pioneer firms and the Forestry industry) little useful information relevant to British conditions was available.

 

Today these updated notes are offered in response to the sheer number and diversity of potential subjects of hardy, ornamental woody plants which are now available and could reasonably be propagated from seed. This state of affairs results from the immense expansion of woody plant material that has been discovered, collected, introduced and has subsequently matured in cultivation, in the UK, since the Second World War. It also reflects the increasing sophistication and knowledge of the gardening public in the UK which seeks to acquire more exotic woody plants and therefore also the retail trade which seeks to satisfy this niche market.

 

As previously, these notes have been developed in the context of the relevant requirements of nurserymen, lecturers and students, other professionals and interested amateurs, in the UK, who need to be able to produce seedlings of hardy ornamental woody plants in a productive and economic manner.

 

In nature the reproduction of woody plants by the production of seed is generally a highly efficient but, nevertheless, improbable process insofar as the number of successfully established offspring as a proportion of the seeds produced and dispersed is more often than not infinitesimally small.

 

The germination of the seeds of woody plants of both warm and cold temperate climates is often delayed by the development of (sometimes complicated) strategies and mechanisms to block germination – in broad terms these are referred to as ‘Dormancy’ controls. These systems have evolved to synchronise the appearance of the new plant (seedling) with the occurrence of the most favourable environmental conditions for the process of germination of the seed and to maximise the chances of successful establishment and survival of this seedling. The objective of the propagator, therefore, is to determine the nature of these mechanisms and strategies for any particular species. These can then be analysed, interpreted and evaluated so that reliable, accurate, effective and suitable practical techniques for overcoming, eliminating or avoiding them can be developed. Thus, as a result, protocols can then be created to develop and establish a sequence of suitable treatments in order to achieve germination and seedling production in the most reliable and productive manner, with a speedy and synchronised emergence and within an acceptable time scale.

 

This philosophy, however, does not imply that every single seed in a sample should germinate but may, in complex cases with difficult, variable or poorly understood dormancy factors involved, allow the germination of the greater proportion of seeds in the sample with the sacrifice of the remainder - in order to achieve an economic outcome in a reasonable time scale.

 

The nursery production of seedlings of woody plants in temperate climates is undertaken to produce a variety of end products. Effectively there are a number of distinct types of commercial producers, generally with a particular market emphasis. The scale of production is also variable insofar as the operations vary from the large (field) scale and extensive to the, often, small scale and intensive. This, in general, tends to reflect the value of the end product, the sophistication of technique required and the necessity for an economic and productive return.

 

Traditionally, in the UK, the largest seedling producers, in terms of numbers produced, have been the forest tree nurseries. Generally they are producing a fairly limited inventory of timber species under extensive conditions. The system relies on the large scale production of a relatively cheap product; although at the premium end of the market the processes and systems have become, in recent years, considerably more sophisticated and intensive. This tends to be a specialist industry without diversification from the mainstream.

 

The extensive, field scale production of low and medium value seedling crops such as hedging plants, fruit tree rootstocks and rootstocks for the more common ornamental subjects has generally been the prerogative of the continental producer, often working in co-operatives for marketing purposes. Historically the scale of production has been sufficient, collectively, to supply the whole of the European market. Large scale production is an essential component of the business in order to maintain a uniformity of product and a competitive price. Despite this there are several very successful UK producers who are succeeding in this medium priced market place by relying on offering a quality product with scheduled delivery dates. There is also a market in this sector for the production of native species of known genetic provenance for conservation purposes.

 

Over recent decades there has been a significant increase in the seedling production of high value, ornamental woody subjects in the UK – which reflects the increased sophistication of the market place in this country for such material and the overall benign nature of the climate which allows such a wide spectrum of subjects to be grown. This climatic advantage provides, to the local producer as well, a benefit not available to the traditional Northern European producer. The market for individual subjects is generally small but the range is extraordinarily extensive so that economic production must depend on very high levels of individual productivity - which in turn depends on the development of effective protocols and the evolution of an efficient and  integrated system of production as well an understanding of how the market place operates.

 

Thirty five years ago (at the time of the production of Hardy Woody Plants from Seed) the emphasis on seedling production was associated with outdoor seedbeds and growing on for the season to produce a ‘1yr field grown’ seedling. The pregermination treatments were also reliant, in most cases, on the necessary treatments being carried out by the same token - eg the chilling, to break cold temperature dormancy, being achieved by autumn sowing in outdoor seedbeds etc. However productivity was becoming variable as the prevalence of mild winters did not provide a sufficient effect for some species. At this time the artificial pre-treatment of seeds of ornamental woody subjects, in commerce, was still in its infancy and there was very little relevant or reliable information on such protocols. While the situation is far from satisfactory today - much more of the processes involved are understood and the detail of these is available.

 

The production of seedlings in outdoor seedbeds is not addressed in these notes as the process has not substantially changed in the intervening years and what was written then is largely still relevant.

 

Nowadays (post 2010) the production of the seedlings of ornamental subjects is considerably more sophisticated, successful and productive. It has advanced, at its most intense, to the use of controlled treatment conditions, effective timing and a programme of continuous artificial treatment (ie which is not dependent on the vagaries of the natural environment) leading to the production of the liner stage in a container. This necessarily requires a reasonably detailed knowledge and experience - as well as access to relevant sources of information in order to develop protocols which are reliable. It also implies the availability and operation of various specialist bits of ‘kit’ – such as incubators, refrigerators, structures for environmental protection etc.

 

The nature of production is now represented by a much more streamlined and controlled system and should resemble the systems seen in a bedding plant or young vegetable plant production unit than formerly. The diversity of the subject matter in the inventory of a modern hardy woody plant nursery’s seedling production unit however creates an additional issue. It is this latter area of the detailed knowledge which is, almost inevitably, still less than satisfactorily served and it is this area that these notes are intended, where possible, to address.

 

The range of subjects covered in this survey contains several taxa that would be regarded as warm temperate in their distribution and only marginally suitable for cultivation in the UK. However if the projections for climate warming are credible then it may well be that many of these will become more widely planted. It is also relevant that many of the present day plant explorers are seeking provenances of nominally warm temperate subjects at the cooler extremes of their distributions.

 

Today there are several suppliers of woody plant seeds who will provide seed which has been treated, especially to overcome dormancy controls, and which is effectively ‘ready to go’. However the inventory is inevitably limited and there is still much to be said for the ‘control’ provided by self involvement - once an understanding of the processes involved have been achieved.

 

Although the approach in these notes has been based on a scientific appraisal of the information that is available from those plant physiologists working in the field of seed biology, it is essentially intended as a practical treatise and merely attempts to interpret this current status – which is inevitably always in a state of flux.

 

The descriptive material in these notes has been gleaned and derived from a variety of sources – these are primarily scientists, plantsmen/propagators as well as commercial and amenity practitioners. This information has then been incorporated into the knowledge accumulated from fifty years of personal experience.

 

Nowadays the all pervasive internet provides access to unprecedented quantities of literature and information on every aspect of this subject from modern plant taxonomy and the important plant relationships which this unfolds to the intimate details of the requirements for germination of a wide variety of subjects. It is because of this ready access and the fact that the approach is practical, that it has not been deemed necessary to include the literature citations.

 

The objective of this exercise, at its most intensive, is to develop a series of protocols, for each individual subject, so that the entire process from the identification of the source to the production of a liner seedling can be determined by the use of a production process blueprint in order to achieve an economic and productive outcome.

 

The chief difference in approach to the presentation of these notes in relation to specific recommendations, from previous presentations, is the importance which has been attached to the taxonomic relationships of plants. Over time evolution has seen the development of what are now classified as Families and the genera and species within these entities are likely to have developed similar conditions and strategies in relation to seed structure, seed physiology. dormancy and germination (although not necessarily exclusively). This will therefore provide an indication as to the likely protocols needed for the successful seedling production of those subjects for which there is no relevant information available.

 

These notes are intended to provide a basis for the producer of relatively small numbers of seedlings, of a wide variety of subjects, from small samples of seed. Hence there is no emphasis on ‘kit’ for collection, extraction and processing - as most operations will be tailored to the individual subject and will chiefly be by hand work or by the use of ‘domestic’, manually operated equipment.

 

It is recognised that there are also many other professionals, concerned with propagating and growing woody plants, who will need relevant information in order to succeed or to waste less time finding out the hard way! In addition there are always dedicated amateur collectors and growers who need information.

 

It is to this purpose that these notes are offered in order to assemble as much of the relevant information as can be currently gleaned but inevitably it exposes the limited capabilities and knowledge of the author.