Proceedings Library

It has been a herculean task to condense into a 10-Minute talk the 29 year history of mist propagation and at the same time to recognize the contributions made by more than 100 different scientists and nurserymen who have authored over 300 articles and papers on this subject.

First, let us define what is meant by "mist propagation". By "mist propagation", we mean the mechanical spraying of water to maintain a film of water on the leaves and stems of cuttings. As evaporation occurs from this film of water, the temperature of the leaf tissue is reduced below that of the surrounding air and transpiration is markedly reduced. With mist, cuttings can be maintained in a turgid condition even though they are

In the discussion to follow, we will attempt to provide a basis for the panel discussion to follow. I will emphasize research at the University of Minnesota, not because it is necessarily the best but because time is limiting and it is most familiar to me.

There are a number of factors which complicate the study of plant hardiness. Winter damage can be caused by several different environmental stresses. For example, desiccation, early fall or late spring frosts, rapid temperature changes, and extreme low temperatures in midwinter can cause damage either individually or in

The term pre-emergence when in reference to weed control means an application of chemicals after planting but before emergence of weeds. The selection of the chemical to be used for pre-emergence weed control will depend on whether it is being used or applied as a direct or an over all spray on lining out stock. Certain sprays cannot be used on liners even if it is directed at the base of the plants, without taking some chance of producing some injury. But the same chemical may be used quite safely as a granual applied in dry form when the foliage

The first stop was at the Oki nursery in Sacramento. Mr. George Oki, who is well known to the Society through the many papers he and his Production Manager, Mr. Kubo, have presented, was a most gracious host. Their organization is divided into two companies, (1) the Sacramento Nursery, which is the growing organization and, (2) Oki Nursery, which is the sales firm.

While we were in the office we looked at the IBM punched card data processing equipment that Oki Nursery has been using for several years for the routine accounting functions of order writing, invoicing, accounts receivable, accounts payable, and serves to gather sales data which can later be used with production records to forecast sales and project production requirements. This equipment will allow them to move smoothly into IBM data processing equipment which they have

The time required to produce "landscape-size" plants from seed is longer than would be required for the production of plants from either "cutbacks" or stem cuttings. The use of "cut-backs" has been extensive in North Carolina, but several disadvantages of this procedure will preclude its use in the future. Available plants of good quality for "cutbacks" are becoming limited and landowners hesitate to allow further exploitation. Since the preparation for planting results in large wounds on these plant parts, microorganisms frequently damage or destroy a large number of "cutbacks&quo; and lower the efficiency of the procedure.

Propagation by stem cuttings would insure the producer of plants with

From the day this idea entered my mind, I had only one thought, to design and build a valve, powered by the supply of water, and operated by the evaporation of water, fully adjustable, for misting, light and heavy field irrigation. I was fully aware of the difference between theory and practice, and such a valve may have to be rebuilt a hundred times before being practical for production. I decided then, that just to prove my point that such a valve could be built, and to stay within my budget, to design a small valve for one nozzle only, with adjustable timing, all in one unit.

This type of nozzle, would be impractical for the use in large scale propagation, however, it

I am sorry I cannot deliver this paper in person but the illness of my wife makes it imperative that I get her out of this severe northern weather until she recovers. This paper will, therefore, be read by my guest, John Fortney, or someone else assigned by the committee.

We have just now stuck our cuttings for this year — I feel cuttings should not be taken until the terminal bud is well developed. The loss of the terminal bud will give a crooked tree to line out. The lower branches taken from two or three year old field grown trees are best. This growth is pencil size or less, and will run from three to twelve inches in length. Cuttings 18" long or longer will root but take up too much bench room. This side shoot has a well developed terminal bud. We sever it from the three year old field grown tree with a sharp knife, leaving a piece of last year's wood on the

The machine, a so-called weedblower, is basically a turbine-unit mounted on a cultivator and powered from the tractor's P.T.O.

Through an universal shaft and a transmission the turbines are brought up to between 15 – 20,000 R.P.M. The strong jet of air, thereby created, is channeled through flexhoses down to a steel nozzle on a cultivator base, at an 900 angle to the plants in the nursery-rows.

Proper cultivation in the nursery rows will create a small ridge of soil along the base of the plants.

The weed blower works on the principle, that, when very young, the weed seedlings' root system is much shorter, and weaker, that that of the established nursery plants.

So when the weed seedlings appear on the soil ridge in the nursery rows the jet of air will remove the weed seedlings, together with the

In 1961, I reported obtaining up to 52 percent rooting of loblolly pine (Pinus taeda L.) cuttings with indolebutyric acid (IBA) treatment under intermittent mist, but could not regularly repeat this success in subsequent research (3).

In 1962, the Boskoop Trail Grounds in Holland reported good results with ornamental conifers from a combination of IBA and Captan (1). A little later Van Doesburg (2) doubled the rooting of conifers by adding Captan to IBA. Wells (5) at the thirteenth annual meeting of the Plant Propagators' Society, stated that the combined treatment decidedly improved the quality and quantity of rhododendron cuttings. Vanderbilt (4) tested the rooting response of the rhododendron hybrid cultivar Chionoides to 16 compounds,

Watkins (5) in Florida has reported that high humidity, constant temperature and moisture are necessary for speedy rooting. The media used have been clean, sharp builder's sand, peat or sphagnum moss. Gardenias being susceptible to root-knot and other diseases, sterilized or fresh media are required. Root inducing chemicals are not essential, but larger root systems are formed in shorter periods on cuttings that have been dusted with one of the root-inducing agents.

Hartmann and Kester (2) reported that leafy terminal cuttings may be rooted in the greenhouse under glass from fall to spring. A mixture of one-half sand and one-half peat moss was a good rooting

Even reasonably good distribution of the water is difficult to arrange. Really uniform distribution is practically impossible. There are so many different things that must be taken into account — water pressure, nozzle spacing, nozzle height over the cuttings, type and capacity of nozzle, air movement, and a long list of other things. The difficulty is complicated by the fact that nozzles throw circular patterns of water. There is no way to arrange them so they just cover a square. There will always be a lot of

The trend in propagation as well as in the growing of plants has been toward a more controlled environment. For example; shading, bottom heat, mist and the plastic tent, all are forms of environmental control. By rooting cuttings under controlled conditions more consistently uniform results may be anticipated.

Although the use of such expensive controls as growth chambers, in which light, temperature and humidity are closely regulated, is not economical; structures can be used in which these environmental factors are more easily and perhaps less expensively controlled.

For example, a roof-covered pit house, built 7 – 10 feet into the soil and insulated, may be the most ideal unit for the rooting of cuttings. The buffering effect of the soil surrounding this unit could prevent temperatures from getting too high in the summer and too low in the winter. With such temperature control the relative humidity would not vary appreciably. Sudden losses of water vapor from the leaves

Of prime interest to the propagator is the fact that the juvenile form of Malus roots readily from softwood cuttings while the adult roots poorly; not only in low percentages but also with few points of attachment (11). Although there have been reports of the successful rooting of apples, I feel that the situation is fairly well summed up in the East Malling Report for 1964 (1) and I quote, "Some 30

Anyone who has grown an extensive amount of Juniperus virginiana is well acquainted with cedar blight. I have never seen seed beds of this species that have not been infected with this insidious fun.-Us to some extent. This particular fungus has the disconcerting characteristic of attacking the growing tip of the evergreen, thus necessitating a good spray program throughout the growing season.

Over the years the Plains nurseries, including Plumfield, have tried several fungicides but the control has not been satisfactory. For many years Bordeaux mixture was used, and this was followed by a material called Special Semesan, which is no longer manufactured.

The presence of and changes in endogenous, indole auxins in bases of several species of herbaceous and woody cuttings during rooting were determined. The five herbaceous species were Alternanthera bettzickiana ‘Aurea Nana’, Coleus blumei, Chrysanthemum morifolium ‘Dawn Star,’ Pelargonium hortorum ‘Pink Cloud,’ Dianthus caryophyllus ‘Alaska.’ Those species root readily but their root emergence varies from approximately 2 to 15 days. The two woody species studied were Pyracantha coccinea lalandi, which is somewhat erratic in rooting, and Carya illinoensis, which is considered a nonrooter.

Disadvantages of this method are that a longer time is required to produce a tree suitable for field or landscape planting. It is generally less expensive to propagate in large quantities by budding or grafting. Little is known about the variation in rooting response of the large number of crabapple varieties being grown.

Before you can root a Rhododendron cuttings you must get the cutting. Where this cutting comes from and how it was treated before being cut determines not only your success in rooting or rotting it, but also what kind of plant it will make after it is rooted.

There is no real substitute for stock plants in Rhododendron production. If you grow enough plants until they are six or seven years old, you might get by without them. The fact remains that ideal conditions for plants in production do not yield ideal cutting material. Stock plants must be treated differently than those being grown for sale if optimum growth and bud set are

The presence of naturally occurring substances can also be demonstrated in grafting experiments (3).

In more recent years the effect of photoperiod on woody plants has studied by Waxman (5) and others. It has been shown that if one divides a group of actively growing dogwoods (Cornus florida L.) into two groups and places one of them under long days of 15 hours or more and the other one under short days of 12 hours or less, one will observe that the plants under long days will continue to grow but those under short days will stop growth within 2 weeks. In other words, these plants become dormant.

Waxman (5) showed that When cuttings are taken from

With the introduction of the mist system of propagation, the Spruces, like many of the other ornamentals that were reproduced in one of these three ways, have become easy to root from cuttings. The procedure, is very much the same as most of the ornamentals propagated under mist, except that just a little more care should be taken in timing your cutting.

The following is a step by step method that we use at Bald Hill Nurseries, Inc. which has proven to be very successful.

An outdoor mist bed 6' wide is prepared with a layer of peat moss 1½–2" thick. Then a layer of sharp sand 6", thick is, put on top of the peat moss. The sand is then rolled with a roller filled with water for compaction. The sand is leveled off so that the surface area is as level as possible. The mist pipes are

The vapor pressure or relative humidity under the two conditions is approximately the same when the mist is off, near

In 1963, Wetherell (2), of the University of

The following spring we plant them out in beds with 40% shade. Our medium is 50% sharp sand and 50% perlite or similar material. Be very careful not to over water. Our catch is about 65 to 75% and we use the same method for all dwarf spruce.

My Dad first saw it used a few years ago here in Lake County, Ohio and thought then that it would be an ideal system for us. Not having a propagation house and being financially unable to construct one and running a business which included landscaping and the operation of a Garden Centre as well as regular nursery operations, time was always short, good help was always scarce and money even scarcer. Thus we decided this would be an ideal method for us to adopt.

The evergreen cuttings were taken and made in the winter as soon as we were able to get at it, which was usually in late February. When we had made enough cuttings to fill three or four frames, we would set, the frames up out in the shadehouse right on the frozen ground. (This really made them cold frames). Sand was put

Corylus maxima atropurpurea was our first trial and in 1964 100 4–6 inch tip cuttings were made after the first flush of growth had hardened. This would be in the middle of July in our region. Half the cuttings were treated with Seradix #2, the other half with Seradix 3# (Seradix is both in content and formulation similar to Hormodin).

The cuttings were placed in a greenhouse bench under intermittent mist controlled by time

MODERATOR VERKADE: Have any growers rooted directly in the new plastic flats or cube flats in which individual plastic pots are formed into a single flat? Also, after rooting and hardening off, have the liners been put into the field?

PETER VERMEULEN: This is getting to be a rather common process as we discussed here at the mist symposium. There are quite a few people, comparatively speaking, rooting directly in the pot and then going directly to the field. We've done quite a bit of this I'm sure others have, too. There is no particular disadvantage or difference in going from the pot to the field with a plant whether it be potted in the pot subsequent to rooting or rooted directly in a pot. I don't quite understand the question.

ANDREW ADAM: What I was trying to get across are these new cube-type trays which are being used for rooting of a plant or liner under the mist, hardened off

As I read, I was collecting my thoughts for this introduction and I believe that one of the most clear aspects which comes to the top of this mass of information is the greatly increased efficiency in propagating techniques which we have acquired over the past twenty years, especially in the propagation of a much wider range of plants, from cuttings.

I was thinking back to the training which I

I should tell you that my experience is limited mostly to a wide range of deciduous shrubs and a few of the easy broadleafs. Also, it is entirely to outside bed work either with conventional sash or intermittent mist. So you see when this discussion turns to such items as Evergreens, Rhododendrons and Azaleas or to elaborate glass-house installation, I am entirely out of my realm. My observations, however, are that a lot of effort has been put into elaborate

Terminal tip cuttings are necessary for the development of properly shaped plants of certain clones of Taxus spp. In other instances, such as Thuja spp., where apical dominance is apparently equally pronounced, normally shaped plants may arise regardless of the position from which cuttings are taken and cuttings from all positions may root with equal ease.

Success in rooting Ulmus carpinifolia cult. "Christine Buisman" is apparently almost absolutely dependent on the position from which the cuttings are taken.

If root cuttings are made in spring at almost the time when Norway maple blooms in the same area, they will form both roots and shoots concurrently. There will generally be several shoots per root cutting. If these shoots are

Kraus and Kraybill (8) as early as 1918 demonstrated the effect of the carbohydrate-nitrogen ratio on rooting of tomatoes. Cuttings high in carbohydrates but low in nitrogen produced many roots but weak shoots, whereas those high in carbohydrates and higher in nitrogen produced fewer roots but stronger shoots. Cuttings made from succulent stems, very low in carbohydrates but high in nitrogen, all decayed without producing shoots or roots. Subsequent experiments by others have shown that a high ratio of carbohydrates to nitrogen favor rooting (3, 13, 15) in tomatoes and grapes.

Winkler (19) showed that grape cuttings highest in

Two references dealing with the collection of lilac cuttings recommend that cutting wood be taken when the blooms first begin to open (1), and just as the terminal buds are formed (2). The dependence of these development stages upon the weather is shown by the lilac flowering dates at the Arnold Arboretum which reveal that propagators in the Boston area, using these stages as guides, would find variance up to three weeks in different years depending on the weather.

Bos (3) observed that warm days in early spring led to a start in growth on his stock plants of

Essentially there are three ways of controlling weeds:

1. Mechanical Control achieved by the use of tools from cultivators, rototillers, flame throwers, and compressed air through the expert use of the hand.
2. Physical Control through the use of mulches or physical barriers which prevent weed growth.
3. Selective Chemical weed control through the use of chemicals which kill specific weeds without injury to the ornamental crop.

With regard to physical control of weeds, this was the technique used to obtain three year weed control in container grown stock. A black plastic circular disc of

With this introduction, discussion commenced:

Several overwintering problems with specific plants were brought up. It was pointed out that failure to overwinter Cornus elegantissima, so-called, has been observed, apparently because of too much cold in some cases and too little cold for breaking dormancy in others. Hardening of young plants is accomplished by some growers by withholding water. The need for a considerable exposure to temperatures around 40°F. or below for breaking internal dormancy was reviewed.

A variety of methods have been used by members of the group for storing young propagated stock:

Pit storage has been used successfully at the University of Rhode

Hormones in general were not found to be useful for improving rooting of hard wood cuttings. There were two exceptions reported in which deciduous hard wood cuttings of Berberis thunbergi Crimson Pygmy in which hormone soak in IBA greatly increased rooting percentages. A Dutch paper was also cited which indicated that Laburnum vossi hard wood cuttings rooted better with hormone treatments.

David Leach observed that: "Theoretically the activity of any hormone should double with every 10°C temperature increase but this does not appear to be strictly so." Comments from the floor bore out this contention of increased

The word "new" as applied to plants was re-defined to include not only new-born (for example brand new hybrids or selections) but plants that are new to a particular area, for example, Azaleas are now being grown in St. Louis where it was said it couldn't be done. They are new plants.

The New Crops Program at the University of Minnesota Arboretum has been testing potential ornamentals for about ten years and about 150 introductions have been made. Many of these are examples of little known plants that have been buried in collections for years and are now available to the nursery trade. In Minnesota there has been a fine relationship between University and nurserymen. The nurserymen help support to research section. A seven man committee meets twice a year with the University Arboretum staff and

Our senses which help us learn: sight, hearing, and touch, are perhaps the most important in this experience because the actual material we are working with is so small that class demonstration does not have the desired effect and can actually detract from the presentation, unless accompanied with larger models. If the students cannot see what is actually being done, they may get the wrong impression or lose interest and be distracted.

The use of the blackboard is helpful, but not always do our drawings appear to others as they do to us. The use of colored chalk improves this, but still this is a two-dimensional presentation while the actual material is three-dimensional.

I have found that after a preliminary

Rubber budding strips of various sizes are used for grafting. Exposed to air this material loses it elasticity and will fall off. Below ground there is no change so the strip must be cut after a period or it will girdle the graft union.

Raffia is used particularly with bench grafts of grapevines. This material is very good in that it rots in the soil. However, the material must be kept moist prior to planting. If allowed to dry it becomes loose and untied.

Medium to heavy cotton string is frequently used in field grafting. When covered with soil this material disintegrates in two to three weeks. If used in the air then it must be cut.

There are the various types of tapes that are used for grafting. Cloth nurseryman's tape has adhesive on one side. It is commonly used for whip grafting. This item is becoming more difficult to find. The cloth tape will deteriorate in the soil.

Fruit trees and certain shrubs, including junipers, have long been propagated commercially by grafting and budding. Fifteen or twenty years ago we grafted about 20,000 junipers each year at Monrovia Nursery Company. Now we are producing at least 200,000 grafted plants each year and the amount is still growing. The demand for grafted junipers has increased, particularly for forms of J. scopulorum, so that we grew 90,000 grafted junipers last year. Also, in recent years, grafting of ornamental trees has become a common practice.

Grafted plants, of course, can offer many advantages. When the scion and stock are compatible and a good union is made, rapid and vigorous growth can be expected,

Foliar leaching is the removal of metabolites from plant parts by aqueous solutions, (Tukey, 1962). Leaching has been shown to be of importance in plant nutrition, in the distribution and recycling of nutrients in an ecosystem, and in the quality of certain food crops. It has also been shown that many factors may affect the leaching of nutrients. For instance, the age and the maturity of the plant tissue can influence the amount of leaching which occurs from plant tissue. Young, actively growing plants tissue is difficult to leach, whereas, more mature tissue is relatively easy to leach.

There are reports by various workers that cuttings propagated under mist undergo extensive losses of nutrients during the rooting period (See Good and Tukey, 1964). Since a large of number of ornamental plants are commercially propagated under mist, it was of interest to survey cuttings from a wide range of ornamental plants to determine extent of nutrient leaching.

1. Healthy seedlings of sufficient size.
2. Preparation of seedlings prior to grafting.
3. Good graft wood.
4. Proper tools and materials.
5. Proper time for the grafting.
6. A good job of the actual grafting, and
7. Careful follow-up.

I shall later use some slides to show in more detail the above operations and the results obtained.

It is sometimes necessary to mention brand names in order to describe as completely as possible the tools and grafting techniques. However, we are not endorsing or recommending any particular brands as we recognize many others are comparable in quality and as satisfactory as those we use.

The seedlings that we graft in our nursery field are one year old trees. Under proper care these seedlings will have reached a height of 4 to 7 feet and have a caliper of ½

At our meeting at San Dimas, California, in 1962, Dr. Harry Kohl presented a paper in which he pointed out that a variety of factors independently and interacting can influence plant height. These include genetic changes, clonal selection, pruning of tops or roots, light, temperature and moisture. But in this modern age of scientific marvels, people are less interested in some of these very effective but "old hat" ideas than in the use of chemical plant growth regulators.

While many chemicals may alter plant growth, including fertilizers, herbicides, auxins and kinins, it seems well to restrict today's

In the mid 1950's the practice was revived largely because of the findings of Goldsberry at Colorado State University with carnations and has remained as a controversial, ill-understood practice since that time. A summary of a carbon dioxide survey made by Kennard Nelson in 1964 indicated that 1,478,600 sq. ft. under glass, almost all of which was in the northern tier of states, was receiving some added carbon dioxide. In the same summary a brief report of research work on flower crops by workers at six universities indicated mixed

Extensive weed control research investigations involving the testing of chemical herbicides on different kinds of species and varieties of ornamental shrubs have been underway for nine years at the Western Washington Research and Extension Center, Puyallup, Washington. Cooperating on this project is Dwight V. Peabody, Jr., Northwestern Washington Research and Extension Unit, Mount Vernon, Washington. Our weed control studies have been designed especially for nurserymen. The procedure for testing pre-emergence herbicides is as follows:

And I am not at all certain that I am the one to carry on this discussion. A "dyed-in-the-wool" enthusiast by nature, I am often accused by some of my close friends of gross exaggerations known as "Everettisms"! Be that as it may, I shall endeavor to look at the subject with a critical eye.

One has only to peruse the literature as far back as the early years of the 19th century to gain an understanding of the role the native plant of California has played in the worldwide field of horticulture. Especially is this true in the European and

There are many problems that

With all this help at our back those of us in the trade still have our everyday problems in this devious art of artificially encouraging sporogenesis. It is through exchanges of information such as we are participating in today, that difficulties will be alleviated or resolved.

To begin let us review and discuss some of the mysteries about ferns that botanists have unfolded for us.

Stimulation of shoot growth bv supplementary lighting of Rhododendron molle was reported in 1960 and 1963 by Weiser and Blaney (1, 2), by Spicer (4) and in 1964 by Goddard (3). Stimulation of seedlings of rhododendron (R. catawbiense), azalea (R. japonicum × R. molle) and their hybrids with supplementary illumination was reported in 1955 by Doorenbos (5). Weiser and Blaney showed that shoot growth of several clones was greatly stimulated by supplementary low-intensity fluorescent light (150 f.c.) between dusk and dawn. They also reported stimulated growth with prolonged illumination at light intensities of 35 to 50 f.c. and by incandescent light. They experimented with deciduous azaleas under

Main workers have reported that mineral nutrients can be leached from cuttings propagated under mist with the subsequent development of nutrient deficiency symptoms (Ang 1958, Evans 1951, Good and Tukey 1964, Sweet and Carlson 1955, Tukey 1962). Losses by leaching are related to the maturity of the cutting, being greatest for hardwood cuttings and much less for softwood and herbaceous cuttings.

Nutrient deficiencies in cuttings rooted under mist are due to a) leaching of nutrients and b) growth of the cuttings during rooting causing a dilution of the nutrients within the cuttings (Good and Tukey 1964, 1965). In either case it would seem that nutrients added to the cuttings during propagation might be of benefit.

Since it is well known that a broad spectrum of material can be absorbed by stems and foliage (Wittwer and Teubner 1959), application of nutrients through the mist would be an appropriate procedure. Thus Morton and Boodley (1962) observed that poinsettia and chrysanthemum

First — Study your subject. It may take several years of observation before you know the peculiarities of the plant in question. (Unless you are lucky enough to hear about it at a Plant Propagators' Society Meeting, that is.) The parent plant may need to have special care, perhaps more or less water than most, more or less fertilizer, shade or sun.

We have trouble in the Northwest in rooting Juniperus torulosa (Hollywood Juniper.) It seems the only way we can get it to root is by putting it in and after it has callused, take it out, remove the callus, redip with hormone, after which it roots quite well. Of course, this is not very practical. I've been told that cuttings which are very small and soft Will root readily, but ours merely rotted. Bruce Briggs told me he had had the very same trouble, but when he took cuttings from some plants he got from California they rooted "like crazy". I believe this means the

We, at Oki Nursery, have tried to determine how to prevent defoliation. Hormone applications of different concentrations have been used — for example, 650 ppm to 10,000 ppm of indolebutyric acid. We have tried interval misting and no misting, and collecting cuttings from new and old wood at different times of the year. Different ingredients for liner soil mix, rooting medium and variable temperatures and humidity have also been tried.

For the present time, with our experience, we have come to the following conclusions:

Time of Taking Cuttings: We have found that the time of year cuttings are taken has a great effect on the amount of foliage drop. In our area we have found the best time to take cuttings is from August through the middle of October.

Type of Wood: The first and second cuttings, below

Soil Mixes: Our first work was with the same mix used for Rhododendron cuttings, 50% each of sand and peat. The rooting was good, but we had trouble hardening them off for winter. We then tried many other soil mixes, such as saw dust, charcoal, pumice and perlite, looking for one which would give good drainage when the cuttings are set outside for the winter.

Perlite offered many advantages such as drainage, sterility, lightness, and obtainability. However, with perlite alone, the maples failed to root. This was also true with Rhus cotinus ‘Royal Purple’ cuttings tried the same year. This year we did root Rhus cotinus, R.P., cuttings in perlite alone, but under heavy mist.

At the present time, we prefer a mixture of some 40 to 50% peat and Sponge Rok, #3 medium. This mix gives lots of air and drainage.

A sufficient amount of light to obtain a photoperiodic response can be obtained by placing 75-watt bulbs with reflectors three feet apart and three feet above the cuttings.

The light intensity should be no lower than 30 foot candles and the temperature no lower than 60 degrees Fahrenheit. The lights do not have to be operated continuously, but may be flashed on for five seconds every five minutes throughout the night.

During a 14 hour night, for example, an accumulation of only 14 minutes of light would be expended by flash lighting intermittently. A discussion on flash lighting

I imagine it safe to say that from the time he stuck his first cutting, man has been concerned with the medium. Through the ensuing years, as he gradually became more sophisticated in his knowledge of the art and craft of plant propagation, there developed a long list of media that have been tried and tested, accepted and rejected and sometimes tried again. Most often mentioned in recent literature are: soil, sand (variously referred to as brick, concrete, plaster, bank, pit, silica, torpedo, etc.), peat-moss

JIM WELLS: It's impossible to answer precisely; this is where common sense comes into the picture. I do believe that most cuttings are improved by a gradual reduction in misting as rooting develops. I think that you need to have a small bunch of roots on the bottom of the cuttings, 6–10 roots possibly, an inch or more in length beginning to become attached to the rooting medium. That is the cutting is beginning to establish itself again as an individual. About this time I think that a modest reduction in mist application is adopted. And the [reduction] needs to be slowly increased in amount as the plant develops over a period of 2 or 3 weeks.

Now the difficulty in doing this lies particularly with the type of control such as a timer. It requires an on the spot interpretation of conditions by someone and this is almost impossible. Here is a real value of the electronic leaf control. One of the simple, very nice things which