Flowering potted plants
|Infobox on Flowering potted plants|
|Example of Flowering potted plants|
|Stowage factor (in m3/t)||-|
|Humidity / moisture||-|
|Risk factors||See text|
Flowering potted plants
Description / Shipment / Storage / Risk factors
Plants are often produced at locations distant from the point of marketing, thus shipping, often for long distances, has become commonplace in the industry. The extended shipping and/or storage times may result in loss of quality and reduced longevity.
Transporting and storing flowering potted plants challenges commercial growers’ continuing ability to provide a high quality product. Quality suffers when plants are exposed to adverse shipping and storage conditions, such as exclusions from light in closed containers and sleeves, exposure to harmful gases and temperature extremes, poor air ventilation, high RH and vibration. These conditions can lead to deterioration of even the highest quality plants. Further, the environmental and physical stresses imposed upon plants during transit are worsened if plants are improperly produced, incorrectly packaged and/or mishandled during shipping or upon receipt.
Flowering potted plants range from cold tolerant to chilling sensitive and from ethylene insensitive to ethylene sensitive. Quality and longevity are based on flower longevity and leaf quality. A flowering potted plant with yellow leaves has little value even if the flowers last for a long period. Likewise, plant quality is diminished when the flower dies rapidly but the leaves remain green. Problems with shipping may not be apparent immediately following shipping: buds or flowers may drop several days after un-boxing, or leaves may turn yellow or flowers die prematurely 1 to 2 weeks after shipping. Research over the last 15 years has concentrated on the factors providing for the retention of leaf colour while maximising flower longevity.
Cultivar selection and production conditions affect the response of flowering potted plants to shipping conditions. Chrysanthemum and poinsettia cultivars vary considerably in their ability to withstand shipping conditions. Hibiscus cultivars drop buds and flowers as a result of improper shipping conditions. It is likely that cultivar responses of other flowering potted plants to shipping conditions exists but extensive research has not been conducted to elucidate these responses.
Production conditions can play a major role in the ability of potted flowering plants to withstand shipping conditions. High fertiliser levels during production decreases the quality of chrysanthemums, campanula, poinsettia and other plants during and following shipping. In chrysanthemum, terminating fertiliser at flower colour (3 weeks prior to marketing) resulted in a 7 to 11 day increase in longevity, depending on cultivar and fertilizer rate. In potted roses, overwatering of the plants during the final 1 to 2 weeks of production results in rapid losses in plant and flower quality following shipping as a result of damage to the root system.
Four factors – disease, improper temperature, extended shipping duration and exposure to ethylene – will result in either rapid loss of quality during shipping or reduced longevity and quality following shipping. All of these factors can be interrelated in their effects. For instance, packing flowering potted plants in a warm greenhouse or packing area then placing the box into a cooler will result in condensation on the flowers and leaves, thus providing ideal conditions for Botrytis, Powdery mildew or other diseases.
Similarly, use of optimum temperatures may cause problems if shipped for long periods. Production and shipping practices should be used that minimise the potential incidence of diseases. For instance, calcium sprays and reduced fertiliser have been shown to minimise the incidence of poinsettia bract edge burn in the greenhouse, during shipping and in the retail setting. In most cases, diseases, especially botrytis and powdery mildew, will become worse during shipping due to the high RH microclimate created in the closed shipping box.
Temperature management is one of the best methods to maintain quality during shipping. Reduced temperatures lead to decreased respiration and the conservation of carbohydrate reserves and minimises problems associated with ethylene. Optimum shipping temperature varies with species, but plants should be shipped at the lowest possible temperature (Table 1). Chilling sensitive crops are generally shipped at 10°C to 12°C, while those that are not chilling sensitive are shipped at 2°C to maximise plant and flower quality. Ethylene can adversely affect quality. Plants may produce ethylene or plants may be exposed to ethylene from external sources, such as combustible engines and dead and decaying organic matter (fruit, vegetables or flowers). Ethylene is a colourless, odourless gas that can cause many undesirable effects on flowering potted plants at very low levels (25 to 100 ppb).
Typical ethylene injury symptoms include leaf and bud drop, premature aging and leaf yellowing, but other disorders have been identified also (Table 2). Ethylene exposure prior to, during or following ethylene injury depends on the ethylene concentration, temperature during exposure, exposure duration and cultivar. Regardless of the concentration, ethylene becomes more damaging as temperature is increased during the exposure period. Of course, injury is worse with higher concentrations and longer exposure periods. For example, open carnations are 1.000-fold more sensitive to ethylene when temperatures increase from 2°C to 21°C. One of the most effective means of minimising ethylene damage is to reduce temperature, being cautious not to ship chilling sensitive crops at too low temperatures. Also, open flowers are often more sensitive to ethylene than buds.
Several chemicals are available commercially that will minimise the detrimental effects of ethylene. Application procedures and effectiveness on ethylene sensitive crops varies with the chemical but can be a valuable tool for crops that exhibit ethylene injury. The use of anti-ethylene chemicals is especially valuable on chilling sensitive crops, since temperature cannot be reduced.
Flowering potted plant quality can be maintained during shipping provided production practices and cultivar are selected properly and optimum shipping conditions are maintained, including temperature management and prevention of injury from ethylene. However, regardless of the conditions, shipping and storing flowering potted plants for extended periods will lead to decreased longevity. Ideally, flowering potted plants should be stored and shipped for brief periods at optimum conditions.
Potted plants require careful handling before, during and after transportation. Researchers have shown that the potted foliage plants benefit when the following adjustments are made before packaging and transportation:
- light – high light levels should be reduced by 75% over a 5 week period.
- watering - soil should be moist, with water content at 50% of soil capacity during transportation. Soil that is too moist may damage packaging and lead to a loss of leaves. Plants should be watered one day before shipping.
- Fertilization – initial fertiliser rates should be reduced by 25-30% over a period of 1 month. No fertiliser should be applied within 1 week of shipping.
These adjustments help acclimatise plants to darkness in trailers and van containers as well as low light levels in building and home interiors.
Plants that are not properly acclimated will suffer a large loss of leaves or chilling injury. Many plants are placed in greenhouses for 1 to 3 months after being transported long distances, to regain their vigour or finish growing. Severely injured plants, however, will not recover.
The choice of packaging is based on the size of the plant, the amount of foliage, the flexibility of the branches and leaves, as well as their tendency to become entangled or damaged during loading. Freight rates and desired loading density are additional factors to be considered.
In deciding the amount of packaging and subsequent loading procedures, shippers should keep in mind that unprotected plants are subject to cold air and the possibility of being damaged and bruised. Damaged plants produce more ethylene, which causes leaves to yellow, drop or curl downward. Flowers on plants affected by ethylene will fail to open, wilt, or fall off.
Plants must never be shipped or stored with fruit, vegetables or cut flowers as these products also give off ethylene. Flowering plants should be shipped separately from foliage plants. Flowers and fruit should be removed from plants transported overseas in van containers.
Most potted plants are protected during handling and transportation with kraft paper or clear plastic sleeves. Woven polyester sleeves also are available. The sleeves are designed to be grabbed at the top. This provides a means of quickly handling the plants. Large plants with pot diameters that are 430 mm or greater are wrapped with plastic or paper.
Smaller plants also are placed in fibreboard boxes with dividers between plants and a moisture resistant tray at the bottom of the box. Polystyrene foam liners should be used when the plants are shipped to areas with extreme hot and cold weather. The boxes should be clearly labelled to show origin and destination and list the contents as live plants, fragile and perishable. Temperature recommendations and arrows indicating ‘this end up’ also should be marked on the box.
The boxes can be unitised on the pallets and, if kept out of direct sunlight, covered with plastic film to reduce moisture loss and ethylene injury. Plants also are shipped in racks, trays, or ‘open’, without sleeves or boxes in which case the plants are loaded directly on the trailer or van container floor. In domestic shipments, metal racks are sometimes used which provide a means to quickly roll the plants on and off trailers. The loaded racks can be covered with plastic film.
Molded polystyrene foam trays with legs also are available holding varying numbers of pots ranging in diameter. The plants can be grown and shipped in these trays which are lightweight and stackable.
Regardless of the packing method, each plant should have a care and handling tag attached to ensure customer satisfaction. The information provided should include a colour picture, common name, scientific name, recommended light level, water and fertiliser requirements and recommended day and night temperatures.
Bottom air delivery trailers and van containers with provisions for shelves, cargo straps and load locks are recommended for shipping potted plants over long distances. Sleeved plants should be loaded in a pyramid or staggered style with the pot edges supporting the weight in stacks. Once half the height of the trailer/container had been reached, shelving should be installed to support additional plants. Boxed plants that are not palletised also may benefit from shelving which reduces the risk of damage from crushing.
Boxed, sleeved and unpackaged plants should be braced with load lock bars, load gates or other wood bracing to keep them from falling and crushing.
1. Recommended shipping temperatures for flowering potted plants
2. Response of flowering potted plants to ethylene1
|Achimenes||Flower / bud drop|
|African violet||Flower wilting|
|Bougainvillea||Flower / bract drop|
|Browallia||Flower / bud drop|
|Carnation||Failureofflower to open|
|Calceolaria||Flower / bud drop|
|Clereodendron||Flower / bract drop; leaf drop|
|Cyclamen||Flower drop; flower wilting|
|Cymbidium||Wilting of the sepal|
|Gardenia||Flower / bud drop|
|Hibiscus||Flower / bud drop|
|Kalanchoe||Failure of flowers to open; petal drying|
|Pachystachus||Petal wilting; bud blasting; leaf yellowing|
1The degree of sensitivity to ethylene varies with plant species, variety, ethylene concentration, and temperature during exposure and duration of exposure.
2 Petiole droop (epinasty) of poinsettia is caused by upward bending of leaf and bract petioles during sleeving. Table 1 lists susceptible cultivars.
3. Recommended temperature, relative humidity and storage period for potted plants not acclimated to darkness
|Common name / Scientific name(s)|
* These plants cannot be stored in darkness at lower temperatures.
** Recent tests with (gel packed) roses in reefer containers have indicated successful overseas transit periods of 2-3 weeks.
BMT De Beer’s Consolidated Manual on (Dutch) Flower Bulbs, cut flowers/greens and potted plants