Ideal greenhouse structure for growing roses


Generally Quonset type of green houses are constructed. The standard size is 30 m x 40 m with a height of 4 m in the centre and 2.27 m on the side. The roof is made in semi-round shape for easy drainage of rain water. Galvanised iron tubes or square steel tubes are used for the main frame. The covering material most commonly used is UV stabilised polyethelene. The durability of this covering material is however, only two years with light transmission capacity 90 per cent and heat transmission 70 per cent.

While other covering material like polycarbonate or double strength glass have light transmission, capacity 90 per cent, heat transmission 5 per cent, durability of which is 50 years and maintenance cost is low. Fibre glass or tedlar coated fibre glass can also be used with relative advantage over UV stabilised polyethylene. Green houses are fitted with fan and pad, exhaust fan, vent opening, fogging, etc.

Best covering materials are those which are resistant to ultraviolet and infra-red radiation, wind, discoloration and cracking, with the capacity of maximum transmission of light, low transmission of heat; reduced condensation build up for improved sunlight transmission and high durability which resists tears, punctures and photo-degradation. The enclosed structure of green houses generally retain heat load, and the temperature rises inside.

To reduce the temperature, enough vertilation is to be provided and maximum air movement is to be created inside the green house. For maintaining temperature, other methods of cooling adopted are top ventilation through ridge vent, fan and pad system and fogging.

The green house should provide good light throughout the year, and a temperature range between 15 to 28°C. The night temperature should be between 15 to 18°C, and the day temperature should not exceed 30°C in any case. The growth is slowed down with the fall of temperature below 15°C. If the temperature rises above 28°C, humidity must be kept high. Higher night temperature above 15°C hastens flower development, while lower temperature around 13.5°C delays it.

With higher growing temperature above 28°C, quality of flower is adversely affected. During winter months, supplementary lighting is beneficial to improve the quality of ·cut flowers. Vegetative growth, yield and quality of flowers can also be improved with the introduction of supplementary carbon dioxide upto 1000 ppm.

Beneficial responses of CO2 enrichment, however, depends on proper temperature and light management. Excessive variation of temperature and humidity can cause a high incidence of either powdery mildew in the heat or downy mildew in the cold and wet periods.

Rose plants absorb most of the solar radiation entering the greenhouse. In wellirrigated vigorously growing crop, high transpiration rates during morning and mid-day hours dissipate a large proportion of the absorbed radiation as latent heat. The remaining radiation heats the crop and air. During afternoon, with a similar load of absorbed radiation and higher outside air temperature and wind velocity, the crop transpires less than during the morning, yet it still cools incoming air.

Analysis of decoupling coefficients shows that greenhouse plants are more decoupled from ambient climate during morning and noon periods than during afternoons. In decoupled systems, transpiration depends mainly on radiation; canopy resistance and ambient humidity have only a secondary effect. During afternoons, higher wind velocity and lower transpiration rates increase the coupling of the crop to ambient air, resulting in the observed cooling.

Legal Disclaimer

Our website is not responsible for the information contained by this article. Webworldarticles.com is a free articles resource thus practically any visitor can submit an article. However if you notice any copyrighted material, please contact us and we will remove the article(s) in discussion right away.


This article was sent to us by: Latoya Helbsen at 10252010

Related Articles

1. How to choose quality rose plants and take good care of them
Best quality rose plants are to be purchased for complete satisfaction and long yeats of pleasure. The most reliable way to buy roses is from the growers of the roses or ...

2. Best time for planting roses and right distance between plants
There are many variations in climate from country to country, area to area, from state to state and even within state, and hence it is not possible at all to be categoric...

3. How to care for roses in summer and in the rainy season
During summer months flower quality will deteriorate and plant health will also be affected, hence, proper care in irrigating the plants, weeding, spraying of insecticides,...

4. Rose pruning time depends on local climate
Pruning time is mainly governed by the climate of the place. In England generally pruning is carried out in spring, since the bud damages due to cold winds and frost will...

5. Some rose species need special pruning
Miniature roses Plants are pruned to one-half size or 15 cm to 25 cm height depending upon the cultivars and the area in which to grow. Dead twigs are to be rem...

6. Roses react very well to the nutrients found in organic manure
Organic manure is an important source of nutrient element for plants. It plays a . critical role in improving soil physical condition. It improves soil aggregation, which...

7. Why is mulching important when growing roses
To keep the rose ground cool and moist and to prevent weed growth, mulching is done specially in hot, dry periods or cool climates. It provides covering to the soil. Th...

8. The potting mixture influences roses grown in pots
Success of pot rose growing largely depends on the potting mixture. The mixture may vary on place to other. The best pH for the potting mixture is in between 6 to 7, sl...