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.
