From: mparks@cbnewsk.cb.att.com (michelle.lim)
Subject: Re: House plants turning yellow (quite long)
Organization: AT&T
Distribution: usa
Date: Tue, 12 Jan 1993 22:35:10 GMT


Thanks to all who responded to my query about house
plants turning yellow.  I received requests to post the replies:
hope this won't get me in trouble with the people who replied!

Michelle
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From cbnewsk!cbfsb!att!cco.caltech.edu!kelly Sun Jan 10 02:15:42 1993

>Why do house plants start turning yellow?

It really could be any number of things. Primary causes are probably 
too much or too little water. If the leaves are wilting, yellow and
the soil is moist, or if you pull the plant out of the pot and the
roots smell like they are rotting, or  the soil is exceptionally wet,
then its most likely overwatering. Many people can overwater plants
easily since plants will wilt when they are getting too much water
(and many plants are sold in rather inappropriate soils/pots for
long term care, which doesn't make it easier for the consumer,)  
this is due to the plants drowning in too much water, they need air spaces
to breathe in too. The roots drown, and then die, and with a smaller
rootball, they can't support as many leaves as before, so the leaves
wilt. so people think it needs water, so they water, and it stays 
wilted (and more roots die,) and more water is added...a nasty circle.
To fix this condition, you can do several things, first off, let the
plant dry out, don't water. Once it starts drying out a bit, you can
transplant it (or yo can do this right away) into a pot with better
drainage and use a soil mix with lots of perlite/great drainage. Try
and remove any 'rotty smelling' soil from the rootball. transplanting a 
plant at this point is risky, since the plant is already under stress.
If you have the plant in a situation its not happy in (like if
you know it needs more light, and you have in a dark place,) move it
to a place it could be happier. You can cut off any foilage that is *dead*
but i usually wait until i see where there is new growth before i
start cutting, plants are amazing, and can really recover well from
poor situations.

If the leaves are turgid-perky-looking normal (not wilting in other words,)
and the older leaves, toward the bottom of the plant have dropped off, 
many within a matter of short time, then you probably let the plant dry
out at some point, and it was shocked. if the new leaves are green and
you are keeping it moist now, it will recover no prob.
Plants also wilt due to drying out, so they have 'low water pressure'
and can't get the water up the stems where the leaves need it and the
leaves wilt. If you feel the top few inches of the soil before
watering, you can tell if the plant really needs more water. If in
doubt, wait until the plant does wilt, and then you can feel the
soil, and remember what it feels like in the future, and become more
wise in terms of watering your plants. A little wilting due to dryness
(iunless its summer and super hot,) won't kill a plant, and it recovers
quickly once watered. 

Do you remember not watering the plant to a point where *the soil was
dry as a bone* AND the plant wilted? If so, then you've probably had
a few leaves ywllow and drop due to letting it dry out. Most people
notice if the soil is dry or wetish when they water, so think back. 
It would have happened in the past month most likely.

Check the plant over for sucking insects like scale or aphids, sometimes
these are the cause of yellowing new growth.

It also depends on the kind of plant you have. Some plants react
quickly to the slightest stress, and some don't. Some prefer an acidic
environment, like gardenias, and azalias, and their (new) leaves
will start turning a yellowish green when their soil isn't acid enough.
Using a teaspoon of white vinegar ina gallow of water (up to a tablespoon,
depends how your plant/water is,) will temporaily correct the soil, its
most effective when used with a fertilizer and sometimes some iron booster.
Also commercial products like 'miracid' work well. What kind of
plant do you have?
 
Also what leaves are turning yellow? top, bottom, new, old? Are the leaves
wilting or turgid? is the soil wet or dry as of right now?

>I was told I could be overwatering or undrwatering
>them.  How do you tell if you're over or under
>watering?  I water once a week.

Again, just test the soil before watering, if its really wet, wait
another day. 

>Does using soft water harm the plant (I use
>that once in a while when I'm too lazy to go to the

I don't think so. of course distilled water is pretty much best for
everyone, including you and me. If you regularly use a fertilizer
(and you shouldn't be using one on a sick plant, it really
just makes it worse,) like a commercial, non organic fertilizer, than
the (i mean, then , the) salts of the commercial fertilizer *will*
build up in the soil,a nd cause problems. Its best to just use plain
water every 'fourth feeding' to 'flush' out the plant. This advice is
followed by professional growers, especially those with p[lants
sensitive to too much salt like orchids. I use organic fertilizers, 
in which case its pretty hard to overfertilize and you don't have to worry
about salt buildup.

We are getting a lot of rain, and its true, there is nothing better than
nice, clean rainwater. But i don't think soft or hardwater over time
will really hurt your plant significantly as long as you watch pH levels
of the soil. Basically you don't have to worry about it, unless you
have a *really* acid loving plant like gardenias, azalias, etc. Most
houseplants are not *seriously* acid loving. A dose of some acidic compost
dug into the top layer once a year will make your plant very happy
though :-) 

>hard water faucet) and does using *cold* water
>harm them?  Any help will be appreciated.  I love

*cold* water can definitely shock and harm your tropical houseplants.
Houseplants are kept in the house since they can't stand really cold
temperatures, and that includes water. "temperate" feeling water is
just fine. if it feels ice cold, then it will probably shock the
roots. Not hot, nor warm, just 'temperate' is fine or 'cool' water.
as long as its not 'icy'. 

>plants in the house but don't have much experience
>growing them.

I got a lot of info from my local library, i never realized how well
they were stocked with the best up to the date books, if you have
access to one, i'd definitely recommend checking it out, there are
lots of great houseplant books out there, and many very 'non technical'
and 'clean cut'.

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From cbnewsk!cbfsb!att!slc10.INS.CWRU.Edu!ct076 Sun Jan 10 14:11:49 1993

Cold water will harm house plants. I just read an article on the 
subect last week. Sorry I cant remember in which rag. I read lots 
of hort articles. I hort for a living presently.  Ummm... you said
something about watering once a week. That probably isn't enough
but if the light is low and the room temperature is cool it might
be O.K. There a a bunch, BUNCH of variables involved.  Is the plant
getting enough light? warm enough? What thype of plant is it? Maybe
loses leaves in the fall and this is a natural thing. 

Let me know. I'll help if I can.

I'll say this only because I think I have to:
TTThese veiws are my own, not the place I work.

Good luck!  

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From cbnewsk!cbfsb!att!mitre.org!lkahn Mon Jan 11 08:11:53 1993

   This isn't necessarily a watering problem, it could be other things, too.  
Without seeing the plants it's hard to diagnose.  If you describe the 
problem a bit more maybe I could help.
   Are leaves dropping off?  Do you notice any type of bugs?  What kind of 
plants are they and where are they located in terms of windows?  How long 
have they been in the same pots?  
   Aside from water, things like bugs, poor soil, drafts, temperature, 
light could all be a factor.  I usually try not to use ice cold water but unless the plant is really sensitive it probably wouldn't hurt once in a while.

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From cbnewsk!cbfsb!att!att!eos.ncsu.edu!kmedenfe Mon Jan 11 09:06:33 1993

you should let your plants dry out completely between watering so the roots can
get plenty of air as well as water.  when you water most plants you should water
completely, until water runs out the bottom, but it is not good to let the 
plant sit in water for a long time (more than a day or two), so if it does
not reabsorb the water in the saucer, you should dump it out.  i'm not sure
if there is a problem with using soft water. room temperature water is best. i
draw water and let it sit in gallon milk jugs open for a few days so the 
chlorine evaporates, too.  

they could be turning yellow from lack of plant food too, although
overwatering would be my guess.

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