It sounds a little bit like a crazy idea
to water plants with fog.
One of the most important attributes of a fogging system
is the creation of a freely hovering fog of microscopic droplets. If we think of mature plants
which need quite some water for their health the objection is correct
The ideal area
of application for fogging systems is plant propagation - irrelevant whether it is vegetative
or generative propagation. An exception may be meristemal propagation where care for the
"seedlings" plants with fogging is needed when the plantlets are extracted from
the glasses and planted in substrate.
As we have mentioned in other documents one of the
criteria of successful plantlet-raising is the quality of the substrate. We do not want to
go too deep into the various recipes of substrates, we want just to mention that the substrate
should be moist and aerated to provide for fast and healthy root growth.
On the other hand for most seedling cultures the rule
applies that the plantlets should be rather dry during the night when their growth is inactive
to avoid fungal attacks and other ailments which can be caused by too much moisture.
If regular watering is interrupted during nighttimes the
substrate tend to dry off - even if no substrate heating is present
If the humidification
system would now simply restart fogging in the morning - for example controlled by a humidity
feeler - within some days a water deficit would appear in the root are of the substrate,
which can be alleviated only by additional hand-watering.
Installation of a good humidification system is no minor
investment, so the customer can expect to get an automatic system which will need him only
for control tasks and parameter setting
The automated tasks of the system should counteract
especially the drying-off effects in the early morning and prepare the substrate with its
ideal moisture for the coming day.
Plantfog has recognized this necessary "watering
option" since 1986 and developed this function according to the valuable recommendations
of the senior nurseryman Mr. Haas from the Municipal Gardens of Vienna.
The function works once more according to the principles
of water physics. Cool air can take up less water than warm air until saturation. This means
that the dew point will be reached earlier. As the temperature inside an (unheated)
propagation house is still quite low the air will reach saturation rather fast (refer also
to Evaporation Cooling) by means of the cooling fog and the surplus water will condensate.
If the humidity feeler is disabled during this period
and the "watering time" is regulated by a control device the duration and therefore
the amount of condensing water can be precisely set.
A rule of thumb states that approximately a quarter of
the water a nurseryman would add manually during the day is enough for this morning dew.
The amount needed during the day will be provided by the periodic fogging function. By this
setting can be guaranteed that the substrate provides the right moisture while it remains
aerated for the growing roots. The correct setting will be achieved very fast by the observing
nurseryman who knows his cultures best. The success of this rather simple switching option
was astonishing right from the start.
If the propagation houses are heated several short watering
periods can be activated during the day if this promises success. From our numerous reference-installations
we know that with some plant families - for instance Croton, Ficus, Schefflera,
etc - a short activation of the watering function can be beneficial also during nighttimes
at the end of the production cycle.
Plantfog then installed an additional refinement to this
function; with an activated watering option the system starts at dawn (setting by means of
an electric timer) with a preprogramed watering cycle with disabled moisture feeler to insert
fog exceeding the dew point. If the watering cycle is completed the normal automatic cycling
start for a "normal fogging day".
The practical consequences are that propagation can run
a fully automated cycle where the nurseryman can withdraw to controlling.
Our control system „plantfog“ designed originally for
research and development provides all these functions; with the somewhat simpler and therefore
more affordable system „profi-plus“ the "watering option" can be provided
by a simple upgrading if the need arises.