Closed plant windows require additional heating in the cold season, which can be achieved in various ways. It is ideal, Include central heating radiators. However, the air flow rising from them must be shielded in this way, that it does not hit the plants directly and dries out too much. Other heating options are offered by heating cables of various designs and dimensions, or various types of in-house designs. For a very small air space, heating with normal incandescent lamps may be sufficient. Infrared lamps emit, because with them only the objects hit by the light heat up, but not the airspace.
The heating devices can be regulated manually after checking the thermometer or automatically controlled by a thermostat. However, a prerequisite for technical monitoring is that it functions safely, because otherwise damage to the plants by over- or low temperatures can arise. With large plant windows, In showcases and in the greenhouse, the temperature difference within the height of the room must be taken into account. The control thermometer should therefore be attached approximately at the level of the top plants. It is even better to install a second thermometer in the lower part. Temperature differences will be determined within certain limits and they will be used according to the requirements of the plants.
Additional exposure of the plants is necessary at least in the months with less light, to compensate for the insufficient intensity of daylight. But light sources can also be installed for purely aesthetic reasons to increase the decorative effect of a plant window. However, the two reasons are difficult to combine to produce an appealing effect. To promote growth, the light source must be as close as possible to the plant. Due to the very low heat generated by fluorescent tubes, there is no risk of burns, only the visual effect is impaired, since the pure expediency emerges all too clearly. The desire, to let a plant window or a showcase become the dominant room decoration, requires the most uniform possible illumination of the surface. To meet both of the above requirements, Depending on the size, several fluorescent tubes must be installed on the top and on the side. They are to be attached as glare-free as possible, what is easy to achieve. The time required depends on the local conditions and the time of year. An exposure time of 6 to 10 Hours a day is common in horticultural practice. Possible overruns – as long as they remain within acceptable limits – are in no way dangerous for the plants, when the required night's sleep is guaranteed. Ordinary incandescent lamps are cheap to buy and install. Compared to fluorescent tubes with average 7500 Burning hours, however, their lifespan is only about 1000 with higher power consumption and less impact. The illumination of larger areas is more difficult to achieve than with rod-shaped fluorescent tubes; the heat development is also to be considered. If many lamps are used in a limited space, it can have a negative effect on the plants.