Valuable Technical Roses

Very Important Some Valuable
Technical Information on Roses

Export Quality Roses
Thanks to CELdek® System


Case study Morgan roses, production of high-quality roses

The South African company Morgan Roses, was founded in 1996, just outside the town of Warmbaths. Initially, it had naturally ventilated greenhouses covering an area of one hectare. The company has now expanded to encompass 4.5 hectares, producing about six million roses a year. Morgan Roses sells to the local market and exports to international markets, i.e. Western Europe, Eastern Europe, and the Middle East.

During 2001, the average price for roses on the South African market was ZAR*) 0.72 each, while the average export price per rose amounted to ZAR 1.40. It would obviously be of great advantage for Morgan Roses if they were able to export a large percentage of their roses. The only thing keeping them from doing so was the difficulty in growing sufficient high quality roses to meet the quality standards and continuity of supply demanded by the export market. At the time, only about 40% of their roses met these standards.

*) ZAR – South African Rand

Long-Stem Roses – True Market Challenge

Roses are graded according to stem length and bud size. Generally speaking, the market demand is for long-stem roses. In Eastern Europe, there is also a great demand for big buds (i.e. larger than 5 cm). The roses produced by Morgan Roses had, on average, stem lengths measuring 50 to 60 cm and never longer than 70 cm with buds sizes ranging from 3.5 to 4.5 cm.

Although these were acceptable quality roses, they were by no means top quality. Export roses are priced according to stem length, averaging ZAR 0.023 per cm. Producing roses that are 10 cm longer would therefore result in an additional income f ZAR 0.23 per rose. If, at the same time, the bud size could be increased, then the roses would naturally appeal to a much larger market segment.

The indoor climate is controlled by
CLIMATELine – the control system from Munters


By installing the CELdek® System Morgan Roses has been able to:

  • Reduce the temperature inside the greenhouse by 7 °C
  • Romove moisture and reduce humidity during night time
  • Achieve high quality and appearance roses even through knuckle cutting
  • Improve the control of the house environment and limit the temperature and humidity extremes
  • Eliminate the occurrence of powdery mildew and red-spider mite
  • Reduce power consumption
  • Guarantee maximum profit

Controlled Climate – Key to the Success

The root of the company’s problem lay in maintaining the climate in it’s naturally ventilated greenhouses close to the ideal conditions for roses. An ideal climate for roses is 27 °C with a relative humidity (RH) of 60-70%. The Warmbaths region, during the summer months, has a mean maximum temperature of 34.7 °C, with a mid-day RH of 45%.

These outdoor conditions make it impossible to increase production and achieve quality roses. To compound their problems, the climate conditions inside the naturally ventilated greenhouses were hardly better. The temperature frequently rose to 34 °C, and the fogging system in the greenhouses was incapable
of raising the RH above 50% without wetting the roses. This brought about excessive stress for the rose plants, resulting in short stems and small buds. Furthermore, the roses that were grown during the summertime produced what is known as “hollow buds“.

Cool Solution

3,200 m2of greenhouse area
with superbly controlled indor climate.

In order to alleviate the problem, Morgan Roses approached Munters for assistance in designing their new 3,200sq.-meter greenhouse. To enable them to provide a greenhouse climate close to the ideal for roses (27 °C, 60-70% RH), Munters recommended installation of the CELdek® system.

Plants were subsequently transplanted from the existing naturally ventilated greenhouses to the new greenhouse with CELdek® system. The outcome was simply astonishing. The Bianca cultivar plants had produced roses with an average stem length of 60-70 cm, with 80 cm not being uncommon.

The bud size increased to five cm on average. Even more impressive was the fact that nearly all the roses produced in the new greenhouse were of export quality.

According to Mr. Johan Stassen, the farm manager, these were not the only advantages. Other benefits derived from operating the greenhouse with CELdek® system were:

  • Diseases: By keeping the RH at high enough levels and removing the draught across the plant beds, CELdek® system helped to eliminate the occurrence of powdery mildew and red-spider mite. The new greenhouse was also fitted with a so-called virus net, which keeps out the disease bearing insects.
  • Ventilation and CO2: The rose plants in the new houses grew much bigger leaves, with a decidedly darker green color, which aided photosynthesis. Mr. Stassen attributes this to the plants in the new greenhouse receiving substantially more carbon dioxide than the roses in the naturally ventilated houses. This is undoubtedly due to the far greater exchange of air taking place in the greenhouse equipped with CELdek® system.
  • Knuckle cutting: It is common knowledge among rose growers that the “knuckle cutting” pruning technique results in more stems per plant. When this is attempted in a naturally ventilated greenhouse, only thin stems that are not of market quality are produced. This method may be applied successfully, however, in the greenhouse with CELdek® system.

What does Munters do?

The essence of CELdek® system is to provide comprehensive control – from start to finish – starting with the expertise required to provide the right equipment and finishing with all the technical support necessary for a total turnkey solution. In this case the system itself comprises CELdek® evaporative cooling pads, Euroemme™ exhaust fans EM50, ED24 and heaters GP, Euroemme jet fans EMT30, control system, water distribution equipment, drainage gutter, supports and DryMode, moisture removal.

Your business is our business!

We’ve been working with horticultural businesses worldwide or many years. That’s why we have the right answers to your growing problems. Let Munters work out the proper solutions to ensure an efficient, reliable, and easy-to-operate climate for your growing business.