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.

The Tulip
Of all the bulbous plants, the tulip is the most important. Tulips have been extremely popular as cut flowers and garden plants for many centuries. In 2007, about 10,000 hectares were used for tulip bulb production. The tulip accounts for one-third of the total export value for bulbs. The number of varieties being cultivated is also huge. There are more than 3000 varieties registered, while the number being cultivated on a commercial basis is not more than 750. Tulips are classified into various groups based on their flowering period and shape. Some examples are single, double, fringed, lily-flowered and parrot tulips. There are also tulip groups for botanical tulips and their related varieties. For flower bulb production, the tulip is planted in the autumn (October) and lifted in the summer (June/July).

The Narcissus
The narcissus is in third place of the most cultivated bulbous plants and is grown on a total area of 1.700 hectares. The narcissus has always been a highly favoured bulbous plant and has earned a permanent place in the flower bulb sector. Still commonly cultivated are the trumpet and large-cupped narcissi, although there are many, many other interesting kinds of narcissi (or daffodils). In total, there are about 2000 registered varieties! Even so, only about hundred are commonly available. The colour for narcissi is predominantly yellow, but white, pink and orange occur, too. They are used for both planting in the garden or park and for cut flower production. Among the smaller narcissi, the cultivar known as ‘Tête-à-Tête’ is very popular and with almost 600 hectares in cultivation has even become the leading cultivar. The majority of these bulbs are used for forcing in small pots. For flower bulb production, narcissus bulbs are planted in the autumn (September) and lifted in the summer (July).

The Hyacinth
As one of the bulbous plants cultivated almost exclusively in the Netherlands, the hyacinth is another bulb with a long tradition in the flower bulb sector and has always been a favourite for forcing in pots during the winter months. During the last 30 years, more and more hyacinths have also been used as cut flowers. Planting them in gardens and parks has been done for centuries. Of all the bulbous plants, the hyacinth is most cherished for its fragrance. Its colours are predominantly pastel: pink, light blue, soft red, white, light yellow and light orange, but brighter colours such as purple and violet are available as well. The land under cultivation with hyacinths has gradually increased to the present 1.250 hectares. For flower bulb production, hyacinth bulbs are planted in the autumn (October) and lifted in the summer (June/July).

The Crocus
Of all the bulbous plants, this very early spring-flowering corm perhaps gives us the strongest feeling of springtime. With the first rays of sunshine, they stand wide open! Except for a modest number used in forcing pot plants, millions of these corms are used in parks and gardens. Cultivation has fluctuated around 525 hectares in recent years. As most people know, the colours for the crocus are blue, purple, white and yellow. In addition to the most commonly cultivated large-flowering crocuses, there are also small-flowering varieties. And some crocuses flower in the autumn. For production purposes, the corms are planted before winter (November) and then lifted early in the summer (June).

The Iris
Bulbous iris rather than rhizomatous types are probably best known for their unique flower shape comprised of their standards and falls. Of approximately 380 hectares devoted to their cultivation, by far the most of these varieties are blue. Nevertheless, there are also extremely lovely white, yellow and bicolour varieties. Iris are most used for the year-round production of cut flowers. This is done in the field under warmer conditions and otherwise in greenhouses. In the Netherlands, flower bulb growers plant their bulbs in the autumn (September/October). Lifting takes place in the summer (August).

Favourite summer flowering bulbs

The summer-flowering bulbs such as lilies, gladioli, etc. are lifted in September, October and November and then delivered to the merchandising chain through the month of January. After having received their temperature treatments, the saleable bulbs will be sent in early spring to the points of sale where consumers will buy them.

The Lily
Of all the bulbous plants, the lily has shown very considerable growth in terms of hectares cultivated in the last few decades. In 1960, it was being cultivated on just 160 hectares. Now, this figure has risen to 4200! The lily is responsible for 25% of the total export value for bulbs. Its increase in cultivation is primarily due to the new groups of lilies that have been developed for cut flower production. The lily has become a very popular cut flower throughout the world. One of the lily groups, known as the Asiatic Hybrids, offers lilies in orange, red, yellow, white and pink. Also favoured are the Oriental Hybrids with their large white, pink or red scented flowers. Lilies in the Longiflorum Group (including the white ones sometimes known as Easter Lilies) have been grown for a long time, but recent breeding efforts involving the crossing of these lilies with Asiatic Hybrids has produced certain new groups known as the LA-,OT-,LO- and OA Hybrids. These groups are becoming more and more important. In the Netherlands, lily bulb production involves planting the bulbs in the spring and lifting them again before winter. For the production of flowers, the bulbs can be planted throughout the year in many different climate zones, both in the field and in greenhouses.

The Gladiolus
The production of gladiolus corms covers about 900 hectares; this puts it in second place among the summer-flowering bulbs. In terms of the number of hectares used for its production, the gladiolus is close to the narcissus. The number of hectares has decreased somewhat, mostly due to the great interest in lilies. Traditionally, this very colourful bulbous plant has been used for cut flower production in countries with temperate and warm climates, as well as for planting in gardens. These very tall plants have bright, appealing colours: red, purple, yellow, orange and white. In recent years, breeding has considerably increased the colours and flower shapes available in the commercial assortment. For the production of corms (gladioli are not true bulbs), the growers plant the small corms and “cormels” in the spring (April) and harvest them in the autumn (Mid October/ mid November) when they have grown larger.

The Dahlia
Like the gladiolus, the dahlia is also known for its bright summer colours. The only colour not included in its spectrum is blue. Its array of shapes is extensive as is suggested by the names of the various dahlia groups: pompon, decorative, collar, anemone-flowering, cactus, etc. Of all the bulbous plants, the dahlia has the longest flowering period of all: several months. Of the more than 450 hectares planted, most of the tubers find their way to gardens and parks. A small percentage is grown for cut flower production. Growers plant cuttings in the spring (May) and harvest saleable tubers in the autumn (October).

The special bulbous plants
The special bulbous plants are included in both the spring-flowering and summer-flowering groups. This "miscellaneous" group of "other" bulbous plants just might be the most interesting, however. There are dozens (and maybe even hundreds) of them. The number of hectares used to cultivate them is about 500. Familiar representatives in this group are the Grape hyacinths, Fritillaria, Allium (ornamental onion), Anemone, Hippeastrum (amaryllis), Begonia, Scilla, Canna and Zantedeschia (Calla lily). They are planted in gardens and parks, sold in pots, or used as material for cut flower production. Sometimes, a bulbous plant from this group emerges as a major bulbous plant due to its popularity. This happened with the lily and may also occur again with Zantedeschias. The interest in this "trendy flower" is so great that it is being grown on much more land every year.

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

The summer-flowering bulbs such as lilies, gladioli, etc. are lifted in October and November and then delivered to the merchandising chain through the month of January. After having received their temperature treatments, the saleable bulbs will be sent in early spring to the points of sale where consumers will buy them.

Bulbous and Tuberous groups

The classification of ornamental geophytes into bulbous and tuberous groups:

Primary storage and tissue groups	Type	Subclass	Taxa
Bulbous group
	Scales and leaf bases		Bulb		Dicotyledonae Monocotyledonae		Oxalis cernua Most Allium species, Amaryllis belladonna, Camassia, Chionodoxa, Endymion, Eucharis, Eucomis, Fritillaria, Galanthus, Galtonia, Haemanthus, Hippeastrum, Hyacinthus, Hymenocallis, Iris hollandica, Iris reticulate, Iris xiphiodes, Ixiolirion, Lachenalia, Leucojum, Lycoris, most Lilium species, Muscari, Narcissus, Nerine, Ornithogalum, Polianthes, Puschkinia, Scilla, Tulipa, Urginea, Zephyranthes.