You can feel the cool and crisp air in the morning as soon as the calendar says October. Night temperatures are dropping not only outside but also in the greenhouse. Now is the time for planning and preparedness.
Heating and Thermometers
Heaters are checked and the thermostats are set according to the plant needs. To determine how the heater is working and controlling the night temperature, a maximum-minimum thermometer is essential. Maximum-minimum thermometers are situated at plant level on the bench. If under the bench is being used for plants, it is advisable to also place a thermometer at that level.
The Ideal Temperature
In a cool greenhouse environment where plants are wintered over and are going into a dormant stage, you may want to consider making a heated propagation area. A soil propagation box with preset 21°C (71°F) soil cables will provide constant bottom heat, which is ideal for fall cuttings.
Although many heaters are fan forced, this is not enough air circulation within the greenhouse. For the best results, to equalize the greenhouse temperature, it is recommended to install a small circulating fan. Lack of air movement creates a stale environment and in turn encourages fungus growth and other diseases. In the wetter climates, condensation can be reduced if there is constant air movement. Larger greenhouses require two or three circulating fans.
Utilize Natural Sunlight
Sudden periods of sunshine will during the fall can cause extreme temperature fluctuations and greenhouse ventilation is necessary to bring down the daytime highs. Automatic vent openers will eliminate the heat from being trapped and building up. At night the vents will close automatically.
The daylight hours are becoming shorter and supplementary lighting is a must for greenhouse gardeners who have an actively growing plant collection. With the constant warm greenhouse temperatures and not enough light hours plants will become spindly and flowering decreases.