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stoneroz
08-04-08, 12:38 PM
Hey guys and gals.
I was looking for some advice on the matter of over watering.
I am a newbie at growin'. I ran into problems when I switched medium to coco. See I was growin in soil before, and I think I'm getting a little paranoid about letting the roots dry out in their new medium. The coco isn't keeping as moist as the soil, so I end up giving the plants in coco almost twice as much water as the plants in soil.
Anyway, heres a photo of the over watered suspect, see how the tips of the leaves are drooping. Does it look over watered, the temps sre 22-25C and the RH is 60 percent.Thanks for your input.
https://www.thctalk.com/gallery/data/500/medium/sweet_tooth_little.JPG

JPS
08-04-08, 03:39 PM
Droopy tips but on the whole they look fine mate, you'd soon notice if you had over watered them.

Diaper
08-04-08, 04:27 PM
Was that picture taken just after lights on? They often look a bit limp during dark periods, as that doesn't look like a case of overwatering.

The only experienced coco grower I know here is Happy Potter, you might like to drop her a pm, as I'm sure she'd run you through her waterig/feeding regime;)

stoneroz
08-04-08, 06:13 PM
thanks guys. The lights had been on for 4-5 hours. The RH is 60 percent, do you think that has anything to do with it?

organix
09-04-08, 07:45 AM
Hey stoneroz heres some very indepth info on watering coco:


Cocopeat and Watering:
In Hydroponics today, Cocopeat or Coconut Coir is now commonly being used by a large variety of gardeners. Over the last couple of years it has grown in popularity to the point that it rivals other systems in its use. As popular as it is however, it presents unique problems when compared with using inert media such as expanded clay.

Watering represents the first major difference. Even though inert media such as expanded clay hold a certain amount of water, they also have much larger air spaces than cocopeat. These air spaces allow the plant roots to easily obtain their necessary oxygen as well as water. In the case of cocopeat, these air spaces, or pores, are quite small. This results in these pores being easily filled with water displacing the air. Cocopeat thus holds more water than a medium like expanded clay. After drainage, the manufacturers suggest cocopeat holds around 250mls-300mls of easily available water per litre of cocopeat. How much of that water is actually available is also dependent on osmotic pressure of the medium or solution. For instance, at an E.C. of 3.5 (cF 35) there is only half the amount of water available to the plant compared with an E.C. of 0.5 (cF 5).

Frequency and duration of watering seems to create the most confusion when growing in cocopeat. As there are a large number of variables it is only possible to give general guidelines.
When estimating water requirements you need to take account of the cocopeat grade, plant water use and the climatic conditions. There three accepted methods of determining how much water to give your plants.
1/ Volume or Weight Measurement
As the easily available water holding capacity of cocopeat is, according to the manufacturers, generally about 250mls to 300mls per litre of cocopeat you will be able to calculate the total amount of water available to each plant by multiplying the number of litres of peat by .25. E.g. you have 10 litres of cocopeat in a pot. The calculation is therefore 10 x 0.25 =2.5 litres of water available to the plant. This assumes that you are starting with cocopeat that has been flushed with water/nutrient and drained. As you don’t want the available water to drop below 50% you will need to water again when the plant has used 1.25litres. So, how do you know when this has occurred? You can use scales under a pot and check the weight after watering. When the plant has used 1.25 litres of water the pot will weigh 1.25kgs less. You would need to check the scales frequently as the plant will grow and put on weight daily. After one crop cycle you will have a pretty good idea of the amount of water (nutrient solution) required with each irrigation.
Instead of weighing the plants, you can also measure the volume of runoff. For example, a plant in 10Ltrs of cocopeat that has used 50% of its 2.5ltrs of available water will require at least 1.25Ltrs of liquid. If in this case you were to add 2Ltrs you would only get (2Ltrs – 1.25Ltrs = 750mls of run off).
This is working with the same figures as above, i.e. assuming the cocopeat is holding 250mls-300mls of water/liter. You will often hear that cocopeat holds ten times its own weight in water. This is for absolutely dry cocopeat and should not be mistaken for the water available to the plant. Total water and available water are not the same thing, total water refers to the total volume of water retained by the cocopeat but as discussed this total volume may not all be available to the plant due to osmotic pressure.


2/ Evaporation Measurement
Using an evaporimeter will give you a very good idea of how much water has been lost to transpiration which can then be replaced through irrigation. An evaporimeter is essentially a pan with an open top which is filled with water. The water in the pan evaporates over time and the amount of water needed to refill it after 24hrs is measured. This amount of water is then given to the plants over the next 24hr period. Generally, a plant factor is calculated and added to the water amount. This plant factor is a calculation used to determine how much water a plant would transpire in relation to evaporation from the pan. Put simply, a plant will use a different amount of water when compared to evaporation according to its size and the type of plant it is. Thus a large plant will use more water and a small plant will use less water than the evaporation figure. Usually, this would end up being about 150% for large plants grown under lights.
Another way is by calculating the usage according to the climate of the area. A large (1.5 metre high x 2m wide) plant on a hot day (35oC outside) and with maximum ventilation in summer in a Mediterranean climate can use as much as 12 litres of water a day. In a 10 litre pot, this plant will need to be watered 6 to 8 times per day with 2 to 3 litres of water each time. You do need to have some water running to waste, normally 20% to 40% of the amount of the input water. Use correspondingly less with smaller plants, in cooler climates and in winter By way of example, it is entirely possible that a small plant growing in an environment with temperatures ranging between 12oC – 25oC may only need watering once every three to five days. Keep an eye on the drain water. If it starts to come through the bottom of the pot well before the irrigation cycle stops then the medium was probably already wet and you will need to water less.

stoneroz
09-04-08, 10:19 AM
thanks alot, that is very helpful. Now I just have to sort out other teething problems,aghh.

happy potter
10-04-08, 11:26 AM
hi stoner roz i got your pm thanks . im not sure overwatering is the problem and i have to admit ive done it that way too 1.5 litres every other day with no ill effects ( little and often but thats when they are in flower so 'maybe ' ??)now if i can pick the tub up with ease, i water , its just my way .
now what you dont mention is what nutrients you are using ? if they are a month on now they defo need a taste of something asap . and yet again i dont go by rules of thumb i just watch the growth and decide when the time for upping , always better to under feed than over as with the watering .and what ever nutes you use have guides but i would be thinking of upping from 2mls per litre to 3 soon on mine , but they are greedy buggers .
heres something i always refer too when i perplexed as im a bit thick at times but it may help :mr:
http://www.oxitron.com/pdf/kweken_op_kokos_in_potten_en.pdf