Help with yellow leaves!

Bugeye

Well-Known Member
I am not trolling you. I am asking a question because I do not follow your logic. So, you are saying a perfectly aerated soil with perfect structure cannot be over watered. Can you share what you use for soil/medium? If it cannot be over watered I am sure many including myself would love to hear it.
OK, I'll accept you are sincere and seeking knowledge, if you feel I am being sincere in responding, please apologize.

The base recipe I already mentioned is one of several that I know of that are really good. I believe this is the subcool super soil base recipe, but could be mistaken. It does not include amendments, just the basic soil structure stuff: equal parts of coir, large perlite, loamy potting soil, earthworm castings. Some people substitute on perlite and coir, using stuff like peat moss and lava rocks or other aeration chunks.

Because you have excellent drainage and tons of beneficial bacteria in this base mix, you will not get root rot (incidentally an anaerobic fungus). It actually is kind of hard to get root rot in soil because of the bacteria in most soil, it would have to be a soil with really poor drainage to hold enough water long enough for it to go oxygenless or anaerobic. As I previously mentioned in the post you won't read, when you put water down on a soil with good aeration, you push out the old air and pull in new air when you water.

On a base soil like this, if you do put down too much water, it will just come out the bottom of your pot. Shame on anyone that leaves pots standing in water overnight after top watering. My plants leaf structure does not curve at all during or following watering, which will mostly be done daily once they are in the greenhouse. If it gets unseasonably cool and cloudy, I might not have to water that day. I let the plants tell me what they need and don't ever go by a watering schedule.
 

polishpollack

Well-Known Member
I hope you mean by "you push out the old air and pull in new air when you water," that it's only when the water dries from the soil that fresh air is pulled in because that's the only time it happens. The way your write it, this sentence doesn't appear accurate.
 

Bugeye

Well-Known Member
I hope you mean by "you push out the old air and pull in new air when you water," that it's only when the water dries from the soil that fresh air is pulled in because that's the only time it happens. The way your write it, this sentence doesn't appear accurate.
Wrong. As water goes into the soil it siphons or pulls air in behind it, assuming the soil has adequate drainage. That's not my personal theory, that is the physics of it.
 

Bugeye

Well-Known Member
I hope you mean by "you push out the old air and pull in new air when you water," that it's only when the water dries from the soil that fresh air is pulled in because that's the only time it happens. The way your write it, this sentence doesn't appear accurate.
From Jeff Lowenfels "Teaming With Microbes", p. 32 (an excellent read by the way):
Water moves between soil pore spaces in one of two ways: by pull of gravity or by the pull of individual water molecules on each other, or capillary action. Gravitational water moves freely through soils. Picture water being poured into a jar of gravel: gravity pulls the water to the bottom as the jar fills up. Large pores promote the flow of gravitational water. As the water fills the pores, it displaces and pushes out the air in front of it. When the water flows through, it allows a new supply of air to move in. When gravitational water hits roots, which act like sponges, it is absorbed.

Smaller soil pore spaces contain a film of capillary water that is not influenced by gravity and is actually left behind after gravitational water passes through. The liquid is bonded together by the attraction of its molecules for each other (a force known as cohesion, but let's not complicate things) and to surrounding soil surfaces (a force known as adhesion). This creates a surface tension, causing the water to form a thick film on the particle surfaces. Capillary water can "flow" uphill. It is available to plant roots after gravitational water has passed by and as such is a major source of water for plants.

Hydroscopic water is a thinner film of water, only a few molecules thick, which, like capillary water, is attached to extremely small soil particles by virtue of electrical properties. This film is so thin that the bonds between water molecules and soil particles are concentrated and extremely hard to break. Roots cannot absorb it, therefore, but this film of water is critical to the ability of many microbes to live and travel. Even when soil conditions are dry, the soil particulate surface holds some hydroscopic water, it is impossible to remove it from soil without applying lots of heat and actually boiling it off.

Just about half the pore spaces in good soil are filled with water. The other half are filled with air. Water movement pushes stale air out and sucks in air from the surface, so adding water means an exchange of air occurs, which is important. If a healthy soil food web is in place, the metabolic activity of soil organisms uses the oxygen and creates carbon dioxide. The presence of carbon dioxide is a good sign hat the soil contains life; however, the carbon dioxide must be exchanged with fresh air to keep life going.

In some soils, the pore spaces are cut off in lots of places, and air is not exchanged when water flows. In fact, water may not flow at all. These soils have very poor porosity - that is, they lack adequate space between the soil particles. All the oxygen in the soil can be used up by aerobic metabolic activities, resulting in oxygen-less, anaerobic conditions. Organisms that can live in such conditions often produce alcohols and other substances that kill plant root cells.
 

polishpollack

Well-Known Member
Wrong. As water goes into the soil it siphons or pulls air in behind it, assuming the soil has adequate drainage. That's not my personal theory, that is the physics of it.
That's silly. It's atmospheric pressure that pushes air into soil when the water dries, either by root take up or evaporation. Water in soil has too much weight and resists air pressure and must go away to allow air into the soil.
 

Beachwalker

Well-Known Member
So the yellow is working it's way up the leaves and they feel completely limp and lifeless... I could really use some help.
Your pH is off so your soil has become too acidic and that's likely why your getting the yellowing

Also looks too dry, start watering properly by watering the whole pot at once thoroughly and then don't water it again until it's dry
 
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Bugeye

Well-Known Member
That's silly. It's atmospheric pressure that pushes air into soil when the water dries, either by root take up or evaporation. Water in soil has too much weight and resists air pressure and must go away to allow air into the soil.
Perhaps there are multiple ways that air exchange occurs and my information is correct. In any event, my plants are often watered daily and don't get a curved leaf structure, or root rot, and they grow big and stay green and smoke great. LOL
 

SPLFreak808

Well-Known Member
the plant the op put up looks underwatered, could be by root damage or bad water cycle & its even showing signs of low osmotic pressure.

Too much water, not enough or constantly pouring a little at a time will make ot easy to kill off roots in fabric pots.

Polished mentioned that you can't be playing a game of cat and mouse when watering fabric pots and i agree, You saturate it one time and let it dry out and repeat, you DON'T want to underwater in fabric pots unless your environment lets you get away with it.
 

polishpollack

Well-Known Member
That's not quite what I said, which was there needs to be a wet/dry cycle, or at least that's what I've been trying to say. Fabric pots would be good for allowing air to pass to the entire soil mass unlike plastic pots which block most of any possible air passage, except from the top. Root won't take up nutrients from a dry soil. The soil has to be moist at the least. It's a delicate balance where you water to saturation then let dry and water again.
 

70's natureboy

Well-Known Member
Ahh, first grow growing pains. Small plants in big pots can be tricky. That's why most people find it easier to use smaller pots and up-pot when needed. If you were using Pro Mix in a proper size pot you wouldn't be having these over-water issues. The plant could drink it's water and be ready for more water every 2 days. If you keep watering big pots the bottom always stays soggy and the roots won't grow into it. In a proper size pot the roots will grow looking for more water. Hopefully your 2nd grow will improve.
 
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