Flower Bulbs

Infobox on Flower Bulbs
Example of Flower Bulbs
Facts
Origin	Mostly the Netherlands
Stowage factor (in m3/t)	-
Humidity / moisture	See text
Ventilation	See text
Risk factors	See text

Flower Bulbs

Description / Application / Shipment / Storage

Bulb production

In bulb cultivation, a distinction is made between spring-flowering and summer-flowering plants. Growers plant the small bulbs (the planting stock) from this first group that includes tulips, narcissi, hyacinths and crocus in the autumn. The flower bulb grower mulches the rows or beds of bulbs with straw to protect the bulbs during the freezing winter temperatures and/or to prevent the wind erosion of sandy soil. A hyacinth, for example, would freeze during a lengthy period of severe frost.

When the plants bloom in the spring, the grower will usually remove the flowers from the plants. The most important reasons for doing so are to prevent diseases and to encourage growth. Other aspects of cultivation include fertilising, irrigating, removing diseased plants and trueness to variety, and preventing disease. The summer months are the lifting period for spring-flowering bulbs in the period from half June until half July. The small flower bulbs are then separated from the larger saleable bulbs.

Summer-flowering plants such as dahlias, gladioli and lilies, are planted in the spring. The flower bulb grower lifts these bulbous plants before winter sets in, in the period from half September until half November. The cultivation methods are generally the same as for the spring-flowering types.

Flower bulbs are stored at a wide range of temperatures. Storage rooms are kept at temperatures from -2°C to +44°C. With all these different temperature treatments, Mother Nature can really be fooled. It is possible to encourage bulb production during the next growing season, to advance flowering or to retard it, to increase flower production, and even to control diseases. These kinds of treatments are used for flower bulbs throughout the bulb sector: among flower bulb growers, flower bulb dealers, special temperature treatment companies, bulb flower producers, etc.

In comparison with earlier days, the prices for flower bulbs have not risen. This is due to the advanced state of mechanisation combined with the development of large-scaled operations. Planting, applying and removing the winter mulch, deheading of the flowers, lifting, grading and even the traditional bulb peeling are mostly done by machine. This does not mean that labour problems don’t exist, however. In fact, next to the need to improve the environmental friendliness of the growing methods, this is one of the most important concerns for the bulb grower. Every year, it becomes more difficult to find temporary workers for the seasonal harvest peaks.

Environmental management

This may well be the most important concern for today’s bulb growers. Bulb growers are aware that the opportunities for applying crop control agents will only diminish. Permission to use these agents is being withdrawn, the quantities allowed are being reduced, and the permission to use them is subject to increasingly stricter regulations. The various organisations in the bulb sector have now joined the ”Milieu platform” (an environmental consortium for flower bulb growers). Within this consortium, organisations are launching initiatives intended to approach environmental problems in a balanced way. Continued reductions in the use of and dependence on chemical agents, fertilisers and energy are the major topics being addressed. Concrete agreements (covenants) have been made with the government in regard to limiting energy consumption and the use of chemical agents. Results of the environmental discussion include: spray-free zones along the drainage ditches, spraying permits, required inspections of field spraying, modified spraying techniques, keeping fertiliser records, requiring that animal manures be injected into the soil rather than spread on top of it, the growing cultivation of organically grown bulbs, etc.

Bulb flower production

The majority of the cultivated flower bulbs are used for flower production. All the production of iris, tulips, hyacinths, lilies, narcissi, etc, has been preceded by bulb cultivation. Some of this production is done by Dutch flower growers, but a large share of the flower bulbs produced in the Netherlands is sent to similar operations in other countries. Flower growing operations are also undergoing interesting developments. We can see increases in scale, automation and new production systems. New developments include the hydroponic production of tulips, hyacinths and irises instead of soil, and the use of mobile benches. The production processes of flower bulbs and bulb flowers are closely interrelated. After all, there can’t be one without the other, and you need bulbs to get flowers!

Commercial cultivation techniques

In nature, plants usually propagate by means of seed. The cultivation of flower bulbs, however, is not that dependent on propagation by seed. This type of propagation is used only for plants that are difficult to propagate in any other way or when other ways would be far too costly. When propagating by seed, however, it is crucial that the seeds of the parent plant are true to type, i.e. they will produce plants that look exactly (or almost exactly) the same as the parent plant. Examples of bulbs or corms that are propagated by seed are anemones, Winter aconite (Eranthis), ranunculus and Tigridia.

Plant breeding

Breeding by means of seed is indispensable for obtaining new varieties. This involves the crossing of plants with the intention of obtaining new and improved varieties. This activity has been – and still is – of the utmost importance in the flower bulb sector. The current tulip range is the result of more than four centuries of crossing efforts. If a modern tulip variety is propagated from seed, it will produce a multicoloured mixture of descendants, some of which have undesirable qualities! Due to the advances made in crossing techniques, it is increasingly possible to create crosses between species or varieties that would not have been possible in the past. This means that highly desirable qualities, e.g. in colour or habit characteristics, can now be achieved by means of crossing. Even more important is the fact that hopefully there will even be more luck in the future in increasing the plants’ resistance to diseases of flower bulbs. This is extremely important to reduce the use of crop protection agents!

Vegetative propagation

Fortunately, most bulbous plants can easily be propagated vegetatively by means of separation of the "daughter" bulbs from the main bulb (hyacinth) or by dividing the entire main bulb cluster (tulip) into several large and small bulbs. The great advantage of vegetative propagation is that all the desired characteristics will be transferred to the new flower bulbs. Just one tulip bulb of the planting stock will quickly produce two to four "offspring". The narcissus takes somewhat longer to multiply but still grows fast enough to be able to sell about half of the number of lifted flower bulbs. The fastest natural propagation is seen among the gladioli: one large gladiolus corm can produce dozens of small cormels (small corms) in a single growing season. For lilies and hyacinths, growers have to assist the natural multiplication process. Since hyacinths produce few small bulbs on their own, the base of the bulb is cut away or by cross-cutting to stimulate the production of new little bulbs. To speed up lily production, scales are removed from the flower bulb and given a special storage treatment so that each scale produces one or more small bulbs.

Propagation by means of tissue culture

If the normal propagation methods take too much time or if it is important to produce many bulbs of a new variety within a short time, the flower bulb grower can choose to use "test tube propagation". In tissue culture laboratories, small pieces of bulbs or plants are placed onto special growing media containing plant hormones which stimulate the production of new plantlets or small bulbs. Many lilies as well as zantedeschias are produced this way.

Favourite spring flowering bulbs

During the summer months, the spring-flowering bulb such as tulips, narcissi, etc. are lifted by the growers and delivered to the dealers. Export takes place from August to December.