Big Blooms: How to Grow Exhibition-sized Flowers

The range of species grown for exhibition blooms these days is astounding—societies, clubs and organizations exist for a vast number of species grown specifically for competition and showing, while many other growers simply produce blooms for enjoyment or a challenge.

Commonly grown exhibition species include iris, orchids, carnations, roses, fuchsia, sweet pea, geraniums, gerbera, sunflowers, begonias, lilies, chrysanthemums and dahlias as well as a large number of flowering bulbs and many other plants.

While floral shows, competitions and exhibitions are typically highly seasonal and scheduled for times of the year when each species is in bloom outdoors, indoor gardeners have much more flexibility.

The use of artificial lighting, the ability to control day length and hence flower initiation in many species, and heating and cooling mean that exhibition-sized blooms can be grown out of season, even year-round and scheduled to be ready for certain festivities or events when outdoor-grown flowers are scarce or non-existent.

Plus, a high level of advanced nutrition, superior growing substrates, protection from bloom-damaging weather, pests and diseases, and the ability to provide a year-round controlled environment are all factors that make hydroponics the ideal method for growing exhibition cut flowers.

Planting Stock and Flower Cultivars

When it comes to growing exhibition flowers, genetics are vitally important, even the most well-grown, protected, and pampered plant will not produce show-quality blooms if it does not have the right genetics in the first place.

The vast majority of flower species that are exhibited in various competitions consist of well-known named varieties or cultivars that grow true-to-type and are well documented, even recorded with descriptions of color, petal form and type, breeder or hybridizer, parentage, awards won and other details providing extensive data bases for many of the commonly grown exhibition flower types.

Selecting and obtaining these specialized exhibition varieties is always the first step in growing those perfect, super-sized specimens and they are usually well-suited to indoor, hydroponic production.

Many species grown for exhibition are vegetatively propagated to ensure they retain their particular characteristics and often need to be purchased from specialist nurseries. This may be as small cuttings, bulbs, corms, offsets, rhizomes or even as tissue-cultured plantlets, which are shipped out seasonally to customers.

Some exhibition species such as sweet peas, sunflowers, and other annuals may be obtained as seeds, often hybrids, which are more reliable when it comes to flower characteristics than the open-pollinated varieties.

Even when obtaining seed, it is vital to select those described as large flowered or exhibition types of the correct variety if entering the blooms in competitions or shows.

Pruning, Supporting, and Training Large Flowers

One major point of difference with growing exhibition-sized cut flowers as compared to many other plants is the degree and type of pruning, support and training required to obtain that perfect bloom.

Indoor gardens have the advantage as growers are not battling wind, hail, rain, slugs and snails and a host of other environmental issues that outdoor gardeners face, all of which can destroy an otherwise perfect flower in the days before an exhibition.

When size is of the essence, plant manipulation really comes into play. By removing competition from other flowers, buds and side stems on a plant, many species can be induced to grow extremely large blooms as all of the plant’s assimilate is forced into a limited number of flowers. Exhibition chrysanthemums are an example of this process, although it is used on a wide number of flower species.

For single exhibition blooms, these are commonly grown as disbuds, where after the plant has been permitted to grow the required number of long, straight, stems (for chrysanthemums that may be one to three main stems per plant), any side shoots that start to develop are pinched out, as flowers form at the top of these main stems, all but the largest central flower bud are carefully removed.

Without competition from surrounding buds and flowers the single bloom has the potential to reach exhibition size and with some varieties of chrysanthemums this can be up to a foot in diameter.

Exhibition species grown for sprays rather than individual sized blooms are pruned differently to allow several, well placed, perfectly formed flower buds to develop after the removal of the central terminal bud.

Since tall, straight, strong, well-colored and undamaged stems are just as essential as the bloom they carry, support and training systems are also essential.

Exhibition-sized blooms are often heavy, bulky and need to be produced on long stems and therefore need additional support. This can be in the form of stakes, tying to an overhead wire, using layers of flower netting or a trellis-type system for climbers such as sweet peas.

This is particularly important where plants may be grown in solution culture, aeroponics or NFT where plants need additional support from an early stage to prevent plant listing and the development of stem kinks.

Nutrients and Hydroponic Systems for Growing Flowers

Hydroponics gives a high degree of control over plant nutrition and to a certain extent plant balance through the use of nutrient formulations and products, EC and pH control. Vegetative formations higher in nitrogen are typically used in the early stages to promote strong vegetative growth that will become the assimilate source for the flower buds.

Once the plant has been triggered or induced to flower, bloom nutrient formulations are applied to provide the different ratios and higher level of potassium required for this stage of growth.

EC can be manipulated throughout the production cycle to apply slight stress when required to strengthen growth (essential with long flower stems carrying heavy flowers), restrict height or promote good bloom color and vase life after cutting.

Hydroponic systems suited to cut flower production are dependent on the species being grown. Commercially, flower crops such as roses, carnations, chrysanthemums and others are mostly grown in substrate-based hydroponics with drip irrigation. This provides some plant support and allows for the development of extensive root systems in plants which are perennial and may be grown for a number of years.

Exhibition or Fancy Chrysanthemums

For those who are keen on really super-sizing flowers to the next level, an excellent species to work with are the fancy or exhibition chrysanthemum types, which are also termed florist chrysanthemums. These are extremely popular in Japan and China, where they have excelled at breeding and exhibiting some amazingly weird and wonderful chrysanthemum flower types which, like common garden chrysanthemums, are fairly hardy and easy for beginners to grow as well as being suited to hydroponic systems.

Chrysanthemum nurseries usually stock a diverse range of cultivars. Young cuttings from grown plants will flower in their first year and grow relatively quickly.

As with many similar cut flower species, exhibition chrysanthemum types are divided into categories depending on the flower form; these range from the basic single and doubles, sprays or individual blooms, to incurve, reflex, decorative, pompon, spider, spoon, quill, fantasy types, exotics, brush or thistle, anemone-centered and others depending on the shape and arrangement of the flower petals.

Chrysanthemum types are also quite diverse with flowering habit, allowing indoor gardeners to choose those which will be induced to flower under specific lighting programs. Some cultivars are termed ‘summer flowering’, meaning that flowers are initiated under longer day lengths, while others are ‘late blooming’ and flower after the day length has shortened below a certain number of critical hours as typically occurs in fall.

In an indoor garden where lighting can be used to manipulate flowering, growers have a significant advantage over those growing outdoors, where plants can be induced to flower at any time of year provided they are large enough to support the growth of blooms.

However, it is essential that factors such as floral initiation and influence of day length are researched before attempting to grow many cut flower types and this information used to time the development of flower buds.

Another factor to consider when growing exhibition-sized chrysanthemums is that large flowers need large plants to support them. Traditional potted or small garden mums have been bred for compact size and shape, however, exhibition chrysanthemums are bred for flower size and some varieties may grow as tall as four to five feet while carrying flowering stems.

Their height can be somewhat manipulated to fit in with an indoor growing space with use of cutting back, terminal growing point removal and selection of shorter cultivars.

Lilies

While many commonly grown flowering plants might be referred to as lilies, such as calla and canna lilies, water lilies and lily of the valley, true lilies all belong to the genus Lilium.

As with many other exhibition flower crops, lilies have undergone some extensive breeding programs to produce impressive hybrids that are vastly superior to the old garden varieties.

The three most commonly grown types of lilies well-suited to hydroponic production are:

• White lilies, also known as Easter lilies
• Large-flowered colored lilies (Orientals) that have been bred to produce outward facing flowers in colors that range from pure white, purple and pink to dark red
• Asiatic hybrids with mostly white, pink, orange or yellow upright facing flowers

Purchased lily bulbs usually arrive packed in damp sawdust and require a period of chilling (vernalization) before planting out to induce rapid growth and flowering. Asiatic lilies are usually given a chilling period of six weeks, and Orientals slightly longer with eight weeks. During chilling the bulbs must be kept damp at a cool enough temperature (35-36˚F).

Smaller growers are usually advised to purchase pre-chilled bulbs, which will be ready for planting out into the hydroponic system as soon as they arrive. Once planted out, lily bulbs begin a rapid growth phase and the central bud contained within the bulb will produce a leafy stem that terminates in flowers.

Asiatic lilies produce some roots from the stem base and it is these, rather than the basal roots which provide nutrients for the flower stalk, so the bulb must be planted at a depth which allows sufficient room for stem roots to develop.

Standard spacing of hybrid lily bulbs into hydroponic media beds is usually around 4×4 inches, with a planting depth of two to four inches. After planting out the bulbs need to be watered well and provided with sufficient warmth to promote bud growth and stem development.

The ideal temperature range depends on the type of lily being produced. Asiatic lilies produce best within a range of 66-70˚F by day and cooler nights of 52-55˚F, while Oriental hybrids need warmer conditions of 69-78˚F by day.

Lilies need reasonably high light levels and use of artificial lighting to provide night interruption will increase the rate of flower production and help prevent bud loss due to low light. If provided with sufficient warmth and light, most lilies will rapidly produce flower buds in 95 to 120 days.

Lilies grown for exhibition cut flowers can be harvested as soon as the most advanced bud has developed color and blooms should be placed into a solution of flower preservative to maintain vase life as long as possible.

Whichever species of flowering plant you choose for the production of exhibition-sized blooms, the essential factors to remember are: the right genetics, the correct timing and method of pruning, disbudding and support, and providing the right triggers (day length) for flowering, if necessary. A well-run and maintained hydroponic system and good indoor growing environment will take care of the rest.