The Greenhouse Management Floriculture

Plant requirements are the same in a greenhouse as they are outdoors; but the greenhouse, with its gradually evolving, automatic means of supplying conditions artificially, is becoming better and better equipped for plant growth.

For example, light, so necessary for photosynthesis, may be reduced in the summer by shading the glass with whitewash or shades, and in the winter electric light provides additional illumination. Temperature is automatically controlTed by thermostats regulating the steam or hot-water circulation through pipes; ventilation, by similar controls attached to the ventilating apparatus. By means of air conditioning, which is finding its way into greenhouse management, both humidity and temperature may be controlled during either the summer or the winter. (Cold water flowing over tight greenhouse roofs during the summer is, of course, the simplest way to reduce temperature and increase humidity.) In some instances typical home air-conditioning units will serve. Watering, fertilization, and cultivation are taken care of by soilless culture, so that uniformity of growth is obtained and considerable labor saved. With crops growing in soil, automatic watering devices are gradually coming into use in the form of tensiometers and subirrigation for potted plants. Thus in a modern greenhouse practically every phase of the necessary factors of growth may be regulated or will be as greater 4erfection in methods and equipment is developed.

Light. Since many plants grown in the greenhouse are indigenous to climates of varying nature, light regulation is necessary. In the winter time its inadequacy is the greatest of problems because crop maturity must be secured at that time. Artificial light provides the answer except that the needed high intensity is extremely expensive. However, many crops respond to very low amounts of additional light.

In the summer excessive amounts of light must be reduced to secure proper development, as in the case of Saintpaulia, Cyclamen, and various tropical foliage plants. To a lesser degree this is true of rose and carnation, where reductions of light serve to keep the growth soft and flower color of higher intensity.

Humidity. Because of the artificial conditions that obtain in the greenhouse, the air is usually too dry for the majority of crops, and regulation of humidity is needed. It is provided by keeping the walks wet, sprinkling them by hand or irrigating them by systems that throw a 'fine mist on them or in the air. Humidiguides make it possible to determine the relative percentage of humidity, and such instruments should be employed where automatic regulation is not yet practiced. Crops vary in their humidity requirements, which should be learned if perfection is to be attained. For example, rose, gardenia, and orchid need relative humidities ranging, especially -during the warm seasons, whereas carnation, stock, and the various succulents grow much better. Regulation of humidity is likewise essential in the control of various bacterial and fungous pests as well as in fumigation and spraying practices. The most common and universally used method of humidity increase is syringing the foliage with water.

Moisture. Regulation of moisture in the soil is extremely important when plants are grown in the greenhouse. On the ability to water depends one' of the major factors of success, and here to a large extent the structure of the soil and the adequacy of drainage enter in. With perfect drainage (in most greenhouses it is not adequate) and a uniform supply of moisture, good growth is assured, provided all other factors are controlled. The actual practice of watering usually depends on heavy drenching to provide the moisture and a subsequent partial drying to provide the air. Various "breakers" are attached to the hose to reduce pressure without sacrificing volume and thus supply the moisture without packing the surface of the soil. Crops vary considerably in their soil water requirements, so general rules cannot be made. Furthermore, it is important to realize that in bench-grown crops spot watering after planting young or dormant plants is essential. Spot watering refers to the application of moisture to the area around the plants and not the whole bench, until such time as root extension spreads into the soil between the plants. Plants with large root systems require more moisture than those with small ones. Those with fine roots demand less moisture than the coarse-rooted kinds. For example, rose requires more moisture than carnation, saintpaulia less than hydrangea and cineraria. Dormant plants like bulbs, hydrangea in the winter, and rose in pots started for Easter are provided with small amounts of water at first until root action develops. The season of the year likewise has its effect; obviously, during the winter waterings are fewer than in the spring and summer.

SUGGESTED GROUPINGS IN FLORICULTURE

In order to facilitate the selection of plants for various-sized water gardens a few suggestions will be given.

The small tub garden may be placed at the base of a rock wall with irises, rockcress, sedums, Cerastium tomentosum, Festuca glauca, Phlox subulata, Veronica rupestris, and others forming the ground covering next to the tub. The container itself may be planted with many combinations such as one giant arrow head, one waterlily, one water hyacinth,7one umbrella fern, one water- lettuce, and one parrotfeather or eel grass. The umbrella plant may be either in a pot or planted directly in the soil. Other plants may be substituted, but the number should not be increased materially, as each plant needs a chance to develop properly.

A pool 4 ft. wide and 6 ft. long may be arranged as follows: If it is to be seen from all sides, a center group of tall-growing plants will be effective. Papyrus or umbrella plants may be used for this purpose, with a group of lotuses near by. Height should be secured also at the corners. Giant arrowhead, irises, pickerel grass, and papyrus may be placed there to advantage. In the open spaces water lilies and various floating plants will produce the desired effect. Open water should show here and there. If a pool is backed against a grouping of shrubs, height should be stressed at that end. Thales and papyrus will serve well under such conditions.

Larger pools and those of formal settings may have to be planted to correspond to the surroundings. When the latter are informal, many miscellaneous plants are desirable; but under formal conditions, where the pool's edges are to be seen, low- growing plants are to be preferred. Lilies should predominate.

CLASSIFICATION OF ROSES

For proper understanding of the principles of culture it is necessary to know something about the different types and classes of rose. For convenience, they may be divided into two great groups—the bush roses and the climbing roses.

The large bush roses grown for mass effects are extremely hardy, floriferous, and usually free of disease. They should be used to a greater degree than at present. Although they fail to bloom except in the early summer, the ornamental seed pods, or "hips," are very attractive in the fall of the year. Because of their hardiness and profusion of bloom, the baby ramblers and the more floriferous hybrid teas, called floribundas, are perfectly satisfactory, particularly for low borders.

The hybrid perpetual and the hybrid teas form the largest group. They are extremely popular and should be grown only in special beds, not with other shrubby materials. The name hybrid perpetual is misleading, since this type blooms usually only once a season, although some varieties may produce a second crop in the fall. The hybrid teas are really constant bloomers if proper care is given them. Of the two, the former are more hardy and vigorous.

Climbing Roses. This group comprises forms of hybrid perpetuals and hybrid teas that have been hybridized with R. wichuraiana and R. multiflora. The rambler roses are hybrids of R. multiflora and are characterized by having their flowers in large clusters and blooming but once a season. Vigor of growth and bright green foliage, usually of nine leaflets, are peculiar to this type. Crimson Rambler, American Pillar, and Tausendschlin are good examples.

Because of susceptibility to mildew, the ramblers are being replaced by the climbing R. wichuraiana hybrids, which show fewer tendencies to disease and possess greater adaptability to locations. The best varieties belonging to this group are Dr. Van Fleet, Silver Moon, Doubloons, Excelsa, Paul's Scarlet Climber.

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R. centifolia (cabbage rose) is a native of Caucausus and Persia. It is characterized by large globular flowers with numerous petals which curve inward. The flowers are pink and fragrant, appearing in June or July. The leaflets are seven, large and wrinkled with deeply serrated margins. The plant itself is a straggling bush, heavily thorned.

R. damascena (damask rose) is a native of Syria, flowering in June and July and again in the fall. The flowers are borne in carymbose clusters of red, pink, and white. Leaflets are usually five. The plant is upright, growing.

The Floriculture In Pollination

Many of our present-day hybrid lilies are the result of chance cross-pollination by insects. To rely upon such a procedure is not satisfactory, since it is difficult to foretell what might arise from seed produced in this fashion. The better method is to go about the work of crossing systematically. It is not only a fascinating pastime but may also prove profitable if an outstanding product were secured.

Fundamentally, crossing, or hybridizing, consists of the transfer of viable or living pollen from one flower to the stigma of another. Fertilization takes place after the pollen grain germinates, sends a tube down through the style of the flower to the ovary below where the union takes place, and seed is developed. The preparation of the flowers, either pistillate or staminate, should be thorough. Plants selected for breeding should be vigorous. Consideration should be given to size, color, doubling, and leaf characters, particularly those of viviparous habit. Viviparous plants are those which develop new plants upon floating leaves during their period of growth.

The male, or pollen, parent should be covered during the bud stage to exclude insects and prevent them from depositing foreign pollen on the anthers. For this purpose a thin piece of cheesecloth or a translucent, waterproof bag may be fastened about the bud. The pollen may be collected during the second day after the flower opens, the outer whorl of stamens yielding their pollen first followed in succession by the other whorls. The female, or seed-bearing, parent should be emasculated in the bud stage. This means that all stamens and their superimposed anthers should be removed before the pollen ripens. The operation is performed by a pair of forceps reaching to the base of the stamen and plucking it out. Scissors may also be used.

The emasculation is necessary to prevent self-pollination and should be done even though the stigma, or the receptive female organ, matures before the pollen. Removal of the pollen from the previously prepared flower is accomplished by the use of a camel's-hair brush or by the removal of the anthers with forceps and dragging these into the nectar that collects in the concave stigma when it becomes receptive. The petals and the sepals should be cut off partially; the flower, covered with a bag or cheesecloth tied closely about the base and fastened to a rod support. Enough twine should be left with the support to allow the seed pods to drop into the water and ripen normally. To keep a definite check of the crosses, records should be placed upon labels attached to the stake. The work of hybridizing may be done all through the summer, depending upon the flowering period of the types in question. The seeds mature usually, when the seed pods should be collected, the covering removed, and the pods placed in water to allow total disintegration of the covering and thorough ripening of the seeds.

The Flower Plants In Floriculture

Tabulate or diagram the foregoing data in a floral plan. Note that in this plan in Fig. 5 the relation of point of attachment of sepals, petals, and stamens is indicated whether they be alternate with each other or opposite. This method should be used far more than it is. If done before attempting to use a key, there is less likelihood of making the floral parts fit the specifications of the key, and therefore a more accurate diagnosis is obtained.

The Inflorescence. Just as the individual flower has a definite structure and arrangement of parts, so a cluster of flowers has a pattern, or arrangement, on an axis. This schematic plan of flowers on the stem or axis is termed an inflorescence.

1. Solitary Flowers. Flowers may occur singly in either a terminal or an axillary position, in which cases they are said to be solitary. This is seen in the fruit plants of quince and peach, the former terminal and the latter mdllary. The flower may be borne at the terminus of a stalk arising at the ground in a number of herbaceous plants (as with bulbs and corms). The stalk bearing the flower in this case is termed a scape, although it is really a peduncle as with any solitary flower. Such a case is familiar in the tulip, crocus, and violet. Since the term inflorescence implies more than one flower in a cluster, this case may be considered apart from the other two categories.

2. The Racemose Inflorescence. This is the most common situation in flower clusters and consists of an axis of unlimited growth bearing the oldest flovTers at the base and the younger ones progressively upward to the tip. The arrangement is familiar in such plants as hollyhock, lily-of-the-valley, and snapdragon. There are various modifications of this racemose inflorescence, but the general scheme is the same. The more usual ones are as follows:

a. RACEME. The individual flowers of the main axis oi peduncle have little stems known as pedicels, and they are of equal length. Examples are lily-of-the-valley, snapdragon, gladiolus.

b. SPIKE. A spike is similar to the iaceme except that the flowers are sessile; i.e., the pedicel is absent, as in buddleia. Cominonly, the flowers are numerous, completely covering a portion of the peduncle as in plantain. In some cases they are in whorls with conspicuous intervals between the whorls as in salvia.

c. CATKIN OR AMENT. This is a spike or raceme with a slender rachis bearing many unisexual, apetalous flowers, which falls as a whole when mature. Examples are ornamental amaranthus, birch, willow, alder.

d. UMBEL. This is a short rachis bearing long-pedicellate flowers of about equal length, spreading umbrellalike as in Queen Anne's lace, ivy, cowslip, onion.

e. CORYMB. The main axis is elongated, and the pedicels are of unequal length. The lower ones are longest; and the upper, or central, ones are shortest, resulting in the flowers lying in a plane. As in all racemose types the lowest ones reach anthesis first, and the maturing of the flowers proceeds upward until the last one to open is at the apex or what appears to be the center. Candytuft is an example.

f. SPADIX. This is a spike with a fleshy axis (rachis). It is sometimes surrounded or overarched by a very large bract—the spathe—as in calla lily, Jack-in-the-pulpit, monstera.

g. HEAD OR CAPITULUM. Numerous small flowers without pedicels are crowded together on a very short rachis called a disk. Osage orange, sycamore, sweetgum, and members of the Compositae, including dandelion and chrysanthemum, are examples.

3. The Cymose Inflorescence. At the growing point a flower bud is produced so that no further elongation of the axis can occur. The other flower buds of the cluster are produced below this point and hence are progressively younger from the tip of the axis toward the base. This gives a situation called determinate growth. The solitary flower is, in a sense, cymose. This situation is seen in the begonia, kalanchoe, exacum, hydrangea, viburnum, carnation.

The differences in price between the materials should be given consideration when purchased—the superphosphates being much cheaper even when the nitrogen of bone is considered.

Ammonium phosphate is the most soluble form of phosphorus and, where both nitrogen and phosphorus are desired, makes the most satisfactory material of all the phosphates. Monocalcium phosphate . which contains  cent phosphoric acid and is being used in gravel culture solutions, is too expensive for average soil application. It is quite highly soluble in water.

Availability of Phosphorus. Fineness of grinding is important in such phosphorus fertilizers as bone to permit each individual particle being in contact on all sides with soil and later with root hairs Such fineness is not desirable in the soluble phosphates, even though they may change over to a somewhat insoluble form upon contact with soil moisture. This form becomes soluble through the action of various organic acids in the soil, so that at least a portion may be used by the plant.

Phosphorus is utilized by the bacteria and the fungi of the soil and may be tied up for a period but later is released for plant use. As in the case of nitrogen when straw mulch is applied, the loss is only temporary. The spread of roots through the soil causes phosphorus availability, as certain solvents are released by the roots in contact with particles of phosphorus. Hence it is very important that phosphorus in the form of bone or superphosphate be mixed thoroughly with the soil and particularly in the areas where roots abound. The solubility of ammonium phosphate will force its passage to a greater depth than other forms of phosphorus. The rate of phosphorus penetration through the soil is only aboutIA in. in depth per year; hence any surface applications are of little value. It should be mixed with soil whenever possible.

Granulated Phosphates. As pointed out previously, superphosphate should not be used in fine form, and this is also true of ammonium phosphate. Granular materials permit of less care in application. They have much less tendency to stick together. Likewise, the granules expose less surface to the surrounding soil, thereby reducing the amount of fixation (insolubility) of phosphoric acid by the soil.

Applications. Superphosphate  and bone meal may be used at the rate of preferably as mixtures in the soil. If applied to the top, they should be worked in. The beneficial effect from surface applications of bone meal is due to the nitrogen content which, however, is quickly dissipated. If an organic nitrogen fertilizer is desired, tankage is the preferable form Phosphorus deficiency is indicated by dwarfing of plants caused by a small root system. The color of the foliage is very dark purplish green at first with marginal yellowing developing later and followed by dropping of the leaves.

Potassium. Potassium tends to balance both nitrogen and phosphorus by encouraging longer root systems and delaying maturity. It is essential in starch formation and its translocation. It is needed in chlorophyll formation and is helpful in assimilation of carbon dioxide so that in the greenhouse in the winter when light intensity is low, additions of potassium tend to compensate for that lack. In general, potassium seems to add tone and vigor to plants and reduces susceptibility to disease. Dahlia and other root crops benefit by its presence, and the coloration of flowers is sometimes intensified through its application.

Many of our cultivated soils, particularly sands and peats, are lacking in sufficient quantities of potassium for the needs. Even in clay and silt soils continual use without the compensating additions of manures or leguminous cover crops will cause potash depletion, which will result in unsatisfactory growth.

Because potassium is held" by soil particles and thus is not readily leached, large qua ities would apparently be available to the plant. Yet act y a comparatively small percentage is available. As a con quence it has been found that to maintain a high level of this element, frequent applications are necessary.

It is interesting to note that a soil high in colloidal matter (fine particles of soil of gel-like nature to which the property of adsorption is attributed) may come to such a shortage of potassium necessary for its maintenance that when potash is added, little or no effect is produced because of competition between the soil colloidal matter and the plants. Thus, frequently a heavier application of potash may be required on clay soil than on sand, this in spite of the fact that clay soils are usually considered to have more potash than the sandy types. Considering all these matters, the use of potash cannot be overlooked. Likewise, it must be borne in mind that growers of by-gone days did not seem to need to apply potash—they were content with the use of manures and bone meal. And therein lay the story. (1) The soils themselves—more virgin than now—contained enough potash; (2) manure supplies potash in high amounts; and (3) the calcium in bone as well as its nitrogen had and have a capacity to liberate potassium. Thus, frequently, when we apply lime or nitrate of soda, we liberate potash; but a limit is eventually reached, and replacements must be made.

Magnesium is lacking in the soil, potassium magnesium sulphate may be substituted. Since the first two mentioned contain about other materials bearing potash may be used in proportion. As an example, hardwood ashes containing. Potassium deficiency is readily recognized by an initial mottling of the foliage, followed by marginal browning and dying of the lower leaves. This occurs because of the mobility of potassium and its translocation to the younger leaves when a deficiency occurs. Excess of potassium is evidenced by plants of dwarf nature with short internodes. Yellowing of the foliage begins at the bottom and progresses upward. The yellow leaves turn brown and finally shrivel. Extreme overdoses will cause a complete collapse of the plant in a short time.