Gerbera & Roses growing article April 2006
 

CO2 (Carbon dioxide)

During my last business trip to Holland and Canada I conclude that growers in these countries have spent a lot of effort to raise CO2 (Carbon dioxide) levels in their greenhouses. I realize that with the higher temperatures in Australia the windows of the greenhouses are open more and you lose more CO2 to the outside air but from late autumn to early spring CO2 could help to increase the production. Especially when the production in this period is lower than in the rest of the year and it's a "cheap" way to increase production and the quality of your flowers.

The normal level of CO2 in the outside air is around 350 ppm (parts per million). All plants grow well at this level but as CO2 levels are raised to a higher level photosynthesis increases and this result in more sugars and carbohydrates available for plant growth. When the level in a completely closed greenhouse is lower than 340 ppm the production decrease by 10-50% but when the CO2 levels raise above 340 ppm the production could increase by 10-30%.

Most of the time the CO2 comes from the heater which use natural gas or propane and a ventilator which blow the CO2 through small plastic tubes into the greenhouse. A point of attention is that the burner is checked regularly to make sure that the carbon monoxide (CO), nitrogen oxides (NOx) and ethylene stays at a very low level to avoid growing damage. CO2 is supplied to the plants 1 hour after sunrise until 1 hour before sunset, at night the plant don't need CO2.

Light levels in Greenhouse;

In autumn / winter it's very important that the glass or plastic of the greenhouse are as clean as possible. With the lower light levels in winter it's very important that the plants get as much light as possible especially in the colder parts of Australia.

Remove all the white wash of the greenhouse.

Replace plastic before the winter so you have new clean plastic in the darkest period of the year.

Clean the inside of the greenhouse with a high pressure water pump to remove all the algae or dirt.

***Although we trust that this information could be of considerable help to the success of the crop, we cannot accept any liability for the results of your crop. All the information in this growing newsletter is without committing ourselves.

This article is written by Job Roskam of Roskam Young Plants Pty Ltd. and also published in the Australian flower industry magazine.