Date: Mon, 28 Aug 2000 15:58:04 +0930 From: Kevin Cook <K.Cook@bom.gov.au> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2648$foo@default> Subject: Nepenthes: water and humidity
Rather than become further embroiled in vampirism and telepathy, I thought
I'd write what I have learnt about nepenthes and water.
When I got my first plants just over a year ago, my only source of
information was the internet. The advice I picked up was not to give
nepenthes too much water and beware of the water quality. I did not
realise at the time that this advice came from people growing other CPs and
that what they saying was that nepenthes don't need as much water as the
others.
With only a few plants, I purchased bottled "pure" water. As this was
relatively expensive, I tended to be miserly with the watering and as a
result I probably did a lot more harm to the plants than otherwise.
Eventually, as I got more specimens, I gave up and just watered them from
the tap and now they're doing fine. I realise now that I had made two
unfounded assumptions - 1) that Darwin tap water is bad; and 2) bottled
water is good.
When I think about it, if plants are given small amounts of water with,
say, 5ppm "impurities", which sit there until they evaporate, there will be
a gradual build up of impurities in the pot to many times that level. On
the other hand if the pot is regularly flushed completely with water at
10ppm, the level of impurities will stay constant at that level.
We're into Dry Season here which means no rain and lower humidity. I'm
growing my plants on an outdoor balcony which means they're exposed to the
elements to some degree. The afternoon relative humidity has generally
been 30 to 50% the last month or so, but occasionally it drops below 20%
when the winds shift south (temp is always around 25 to 30C). I have to be
a lot more attentive with watering.
As long as they have been watered, the plants don't seem to mind these very
dry bursts. They do acclimatise. Most of my lowland plants and even some
highland hybrids are doing nicely and pitchering. I've got several N.
ampullaria. They have stopped pitchering, but I expect them to form
rosettes when Wet Season starts.
On August 15 I got home and found my very large N. ventricosa x (mirablis x
alata) had gone droopy. Especially distressing was the sight of an
unopened pitcher which was hanging upside down. It made me realise that
nepenthes rely on the turgidity of their tissue to keep these structures
strong. Between two days when the 3pm humidity was 48%, that day the
humidity had dropped down to 18%. This plant also gets full sun for a few
hours each day.
I immediately gave the plant a good flush with lots of tap water and I
propped up the flaccid pitcher. I'm happy to report that both the plant
and pitcher have completely recovered.
Finally on water, I remember reading in an old digest about whether the
lids of Nepenthes pitchers are "designed" to keep out rain. I kept a
number of plants in the garden last Wet Season. Often the rains are
accompanied by driving winds and so the rain can be almost horizontal. My
own theory is that the lids prevent very large drops falling directly into
the fluid and causing the contents to splash out, rather than preventing
the fluid from being diluted by smaller drops and spray.
BTW, the only plants I have killed have been N. ventricosa and N. alata
(you know, they're the ones that are really easy to grow). N.
ventricosa doesn't like constantly warm temperatures and I will
concentrate on lowlanders.
Regards,
Kevin Cook
Darwin
Australia
This archive was generated by hypermail 2b30 : Tue Jan 02 2001 - 17:35:12 PST