Natural gas and propane are popular choices when it comes to heating a greenhouse. The products of burning fuel are carbon dioxide (CO2) and water (H20); both compounds we know are good for your plants. However, combustion is often incomplete, and impurities such as carbon monoxide (CO), sulfur dioxide (SO2) and ethylene (C2H4) are also released leading to poor air quality if your heater is not properly vented.
Typically symptoms from ethylene damage and sulfur dioxide damage can be seen fairly quickly after exposure.
In the short term, ethylene damage results in leaf curling, epinasty - leaves bending downwards from the petiole - and flower drop. If the stress continues over a longer period, several days to a week or more, plants can take a long time to flower, or not flower at all. Ethylene levels as low as 0.01 parts per million can create symptoms in sensitive species. Levels are usually highest near the heater and can be diluted by air circulation.
Upon recovery later in the season, plants will look as if a growth regulator was applied, highly branched, and even a bit darker green. On the bright side, if the stress was short your customers may enjoy this side effect.
Read the complete article at www.onfloriculture.com.