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A guide to watering

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#1 Mr Pothead

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Posted 24 May 2014 - 02:46 PM

A Guide To Watering.

Figuring out when to water your plants can be tricky, especially for new growers, so hopefully this quick thread will help.

After over-feeding, the most common cause of plant failure is over-watering! The roots need air as well as water and should not be constantly drenched. The symptoms of over-watering are unfortunately similar to under-watering... the plants wilt, the leaves and branches sag, brown patches appear on the leaves, the roots start to rot and if left untreated the plants die.

How often should i water the plants, what time of day and how much should i give them?
There is no definite answer as it depends on many things:.. warmth of the grow-room, the light's used and distance from the plants, humidity, size of pots, growing medium (soil) and various other factors.

There are a few things to look for when deciding when to water:

*Is the pot very light? - Around 90% of the weight of compost is water, so if the pot is light and much easier to pick up than normal, a watering is needed.

*A gap around the edge of the soil in the pot? - Soil shrinks as the water is used up, so a gap around the edge of the soil is a good sign that water is needed.

*Does the soil stick to a pencil? - Gently push a long pencil into the edge of the soil in the pot, if it is not damp with bits of moist compost stuck to it when you take it out, then a watering is needed.

* Wilting? - A plant will wilt (droop) when it needs watering, usually starting at the lower leaves working up the plant. If your plant is wilting then a watering is urgently needed.

*What time of day? - Personally I prefer to water when the lights come on rather than when the lights are off (or due to go off), simply due to humidity. Humidity rises at night which if not kept in check can cause problems, watering just before the lights go out means there's more surface water on the soil which will increase the humidity in the grow room a lot. Watering in the 'day' will keep the humidity relatively constant.

*How Much? - Again this can vary dramatically depending on pot and plant size etc, but what most growers do is: with a tub/tray under your pot, water *slowly* until the surplus runs from the drainage holes at the bottom of the pot... allow the pot to stand in the surplus water for 10 minutes to soak up any more that is needed before emptying out the run-off tub.

The smaller your pots the less water you might need to give... a little 4" starter pot for seedlings under a CFL light may only need watering once a week with half a pint of water, whereas a 10 Litre pot holding a big plant under a HPS light may need 3 or 4 litres of water 2 or 3 times a week! Remember, wait until the pot is light and the compost dry before watering again, and just because the top inch of soil is dry doesn't mean that the soil around the roots is!

As with feeding your plants, a good rule of thumb when watering is: better to give less than too much! Hope that helps a few of ya!
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#2 scooby


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Posted 26 April 2015 - 09:31 AM

Can I say something about the time of the day to water a plant. 


I used to water my plants just after lights on, to basically, like you mentioned, be able to control humidity a lot better during lights out. 


However, a horticultor told me that it's not the best time. 



During the day the plant absorbs light as we know, and I won't carry on with explaining what happens, I reckon we all know.

At lights off, we think that the plant is "sleeping", not growing. Well that is in a way true for the part of the plant we see, but during that time, the roots work hard to produce the energy and share the nutes to different parts of the plant that we see. Therefore, it makes real good sense to feed your plants just before lights out, simply because the fresh nutes will benefit the plant a lot more, since it's at that time that the roots look for those nutes. Watering at lights on gives you a whole day before next lights out to loose a percentage of your nutes through evaporation.


English isn't my first language therefore I hope I made sense there guys.


PS, I do not want to argue with anyone, I have many times and still do a lot feed at lights on simply because it suits my "personal life" schedule better, but I'm very well aware that the plant would rather me feed her just before lights out. I


PPS I do recommend to top or defoliate a plant and feed her just before lights out, for quicker recover and less stress. 


PPPS A plant is apparently supposed to "wake up" at approx 4:30 am, this is when the roots go to sleep and the leaves (the parts we see) come into life. Between 4:30 and 5:30 pm is when the roots are supposed to "wake up" and the above ground parts go to "sleep". This seems also true, I have many times noticed my plant's leaves droopy just before lights out....My lights go on at 6am and off at 6pm during flowering....to suit me, but it would be apparently perfect to switch lights on at 4:30am....The gardner who told me that has studied plant lifes for a long time, his advice has never failed me. I thought I would share what this person has taught me.


Food for thoughts. 

Edited by scooby, 26 April 2015 - 09:35 AM.

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#3 ZenArcher


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Posted 26 April 2015 - 10:29 AM

Thank you for sharing this scooby, It's  something I'll keep an eye on and switch to feeding at night as what you say makes sense and can't do any harm to try it.


Your English is very good, you only made one small error in your Exploitation paragraph, used loose instead of lose, I've seen many English speakers do this so not a big deal.   


Thanks again for this interesting topic.  :) 

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#4 scooby


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Posted 26 April 2015 - 10:39 AM

YOu're welcome ZenArcher. As mentioned, the guy is a gardner and has studied plant life, all the biological stuff that looses me :). When I do feed just before lights out, which I try the majority of the time now, I do notice the difference the next morning. Could be my imagination but it's not hurting the plants that's for sure. 


The topping and defoliation should be done at lights out, for recovery purposes. And a feed should always be given to the plant at that time...makes sense to me.

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#5 Hoon


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Posted 26 April 2015 - 11:40 AM

interesting food for thought , however the plant going to sleep/waking up, how well does this translate into a artificial environment , would it lets say be the same for my plants that have night in the day and day at night for a steadier night day temps, 


it may just be me but i always seam to notice a rapid growth spurt after every night period ?

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#6 scooby


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Posted 26 April 2015 - 12:01 PM

It don't matter it's all to do with moon and sun. Believe it or not even indoor the plants are affected by those.

It seems that putting them on the opposite light cycle from their natural affects them with regards to nutes intake. Apparently they intake less or not so easily. Same for feed at lights on the roots aren't working as good at that time. This what am told I haven't studied it but it does make some good sense.

The only time I see the biggest development in my plants is the morning after my feed but like you said imagination maybe. .....
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