Re: humidity and stuff

From: Paul Temple (
Date: Fri Apr 09 1999 - 04:34:55 PDT

Date: Fri, 09 Apr 1999 11:34:55 +0000
From: Paul Temple <>
Message-Id: <aabcdefg1253$foo@default>
Subject: Re: humidity and stuff

Some kind of humidifier or fogger would seem the best bet, (non-
mains water?) but can you get ones for really small
greenhouses...2ft by

6 ft? Otherwise, is there some simple-but-effective non-electrical

Yes. But such things are not cheap!

The type of water is irrelevent except that if you don't use tap
water from a mains supply, you will have to create pressure to
deliver the water. This usually means you need a pump (except if
you live at the bottom of a cliff and collect rain water at the top
of the cliff!!!). Because most people want the pump to be
automatic, you need a pump that starts when a timer or sensor opens
a valve reducing in-line pressure. The pump must also be
self-priming so that it can pump out air gaps to reach water held in
a reservoir. Basically we are talking about 150 UK pounds (($220
US) minimum.

Moving to the humidifier system, starting at bottom end of market
(still not cheap), you can use a mister - a fine spray jet. Since
Neps are (I think) mains water tolerant you could deliver this via a
mains water poered hose, switched on and off by a normal time clock
(either a tap computer or a time clock wired to a solenoid valve.).
Don't use micro-sprinklers at all if possible as they clog up with
either algae(if using rain water) or calcium (tap water). Plume
sprays are better and easier to clean.

Better is a fogger unit or humidifier. You can use household types
but they are a real problem as they do not autofill with water and
the delivery of the cloud must be channelled away from the
humidifier before entering the greenhouse. If you put the whole
unit in the greenhouse, it rusts and you lost 70 UK Pounds ((about
$100 US) wortyh of equipment in about 2 months!!! However, there is
a good humidifier designed for greenhouses - but at a price. It
will cost about 130 - 150 UK Pounds (($200 US approx.).

Of course, you will then want to consider sensors for humidity. You
can do without them by having clocks that switch humidifiers on -
experiemnt with them unitl they deliver the required humidity.
However, with clocks alone you will get varying humidity depending
on the weather conditions. So you really need a sensor. These can
cost just about anyting, from about 15 Pounds ($20) to several
thousand pounds if needing to maintain humidity within 1% accuracy.

My overall suggestion is that you chat to one of two companies.
(Reading their literature helps but it contains only part of their
stock. The serious plant people visit and talk to them.) Two
companies, both in UK (but overseas readers may want to know they
will export) are:

Simply Control, 139 The Commercial Centre, Picket Piece, Andover,
Hants, SP11 6RU Tel: +44 (0)1264 334805 FAX: +44 (0)1246 335755

Two Wests and Elliot, Unit 4, Cartwood Road, Sheepbridge,
Chesterfield, Derbyshire S41 9RH Tel: +44 (0)1246 451077 FAX: +44
(0)1246 260115

Both companies will have most of what is needed by growers who are
either beginners or experienced in greenhouse automation. But be
warned - to start doing things like controlling humidity properly
costs about 150 UK pounds at an absolute minimum in the UK (or about
25 Cents in the USA where you can get anything from a choice of
catalogues, but we can't get the USA based catalogues in the UK!!!).

Both companies above send out catalogues on request. Neither yet
has a Web site or email.

Going back in time, my uncle grew Bromeliads and these liked high
humidity. To maintain it, before mister systems were invented, he
used to have the greenhouse floor covered in shallow water
containers each filled from the tap via a standard ballcock valve.
Each tray was heated using copper piping attached to a heating
source pumping hot water through the pipe. He supplemented this
with hand spraying of the plants whenever he looked at the
greenhouse. For a small greenhouse such as yours, the whole floor
could be a water tray (about 30cm deep). The ballcock valve (or
equivalent) could be adapted such that it measured and maintained to
water level in the tray but when letting water in, did so through a
high level spray (not too fine a mist), which would both spray the
plants and fiull the tray. This is as cheap a method as you can get
but it will never maintain a constant humidity of 70% unless you pay
a fortune to heat the water trays!!!

None of this is specifically for Nepenthes, just for humidity in a
greenhouse. As someone said when subject was raised a few days ago,
the smaller the space, the harder it is to maintain the humidity at
a constant level. (The same is true once you start getting into
very big spaces but this is only really a concern for Botanic
Gardens or people rich enough to afford bot. gdn. sized

Expect to spend a significant amount of time researching, buying,
setting up and then adjusting everything before you end up even
satisfied with what you decide to do. There's no simple solutoin I
know of that you can just buy off a shelf, install and forget about.

One warning. Most people who automate any part of their plant
keeping end up learning the same mistake which you might want to
think about avoiding. Because of the cost of everything, almost
everyone buys one of everything major (one pump, one humidifier, one
sensor, one valve, etc.). So, if any single thing in the system
fails, the whole system fails. This is not the problem. The
problem is that the first time a person automates, the quickly rely
on the automation. The first time someone does this, you can be
certain it will break. The result is a lot of very unhappy or even
dead plants. So the trick is to duplicate everything (more money) ,
fit alarms (more money) to warn you of unwanted conditions and yet
still to ***never*** trust the automation.

Hope this all helps.



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