PH and light strength, is there a relationship?

[beard o]

I tend to overthink things so forgive the dumb question.

But is there a connection between pH ranges and light strength? I understand the accepted pH range is from 5.8-6.5, and I'm hyperfoused about maintaining it.
However, do these pH ranges apply to all lights? I run a 1000w MH in veg and a 1000w HPS in flower. Do the same pH ranges apply to someone using a 160-400w LED or doesn't it matter?

 

[Phytoplankton]

Yes, applies to all lights.

 

[Skunksta]

pH is all about the medium you grow in and what it asks for maintain jobs a good one.
Lights will have no impacked on your ph or reason to change it in my led grows.

But willing to learn along with the op.

 

[Bill284]

I tend to overthink things so forgive the dumb question.

But is there a connection between pH ranges and light strength? I understand the accepted pH range is from 5.8-6.5, and I'm hyperfoused about maintaining it.
However, do these pH ranges apply to all lights? I run a 1000w MH in veg and a 1000w HPS in flower. Do the same pH ranges apply to someone using a 160-400w LED or doesn't it matter?

Ph depends on what you have in your pot.
Coco 5.8
Bx 5.8
Soil 6.4

Light will effect how much they eat.
No effect on ph.


Stay safe
Bill284

 

[seaofgreen18]

pH is all about the medium you grow in and what it asks for maintain jobs a good one.
Lights will have no impacked on your ph or reason to change it in my led grows.

But willing to learn along with the op.

Howdy alls i can say is if your ph is off no need for alot of light and vica versa ph spot on more light! Just don't overdo the light

 

[seaofgreen18]

Living soil 6.8

 

[Skunksta]

Howdy alls i can say is if your ph is off no need for alot of light and vica versa ph spot on more light! Just don't overdo the light

I was trying not to be insulting to the user who commented before me.
By saying willing to learn instead of you talking £$^*
happy growing all.

 

[seaofgreen18]

Living soil 6.8

Bacteria like 7.0 ph and the more complex like fungi and protozoa like a little less than neutral below 7.0 so its in-between for both to survive as well as the higher ph limits heavy metal uptake if present in your soil

 

[Trump]

Ph depends on what you have in your pot.
Coco 5.8
Bx 5.8
Soil 6.4

Light will effect how much they eat.
No effect on ph.


Stay safe
Bill284

Yes. pH doesn't affect lighting and vice versa. As @Bill284 mentioned, light intensity will affect nutrient uptake.

The higher the PPFD the higher the intake of nutrient due to the accelerated metabolism from the higher leaf temp the higher light intensity will provide. Of course all of this needs to be in balance so if there aren't enough soluble ions in the soil or whatever medium you're using you'll just fry your plants.

 

[beard o]

Yes. pH doesn't affect lighting and vice versa. As @Bill284 mentioned, light intensity will affect nutrient uptake.

The higher the PPFD the higher the intake of nutrient due to the accelerated metabolism from the higher leaf temp the higher light intensity will provide. Of course all of this needs to be in balance so if there aren't enough soluble ions in the soil or whatever medium you're using you'll just fry your plants.

Ok thanks.

On this grow I switched from a 600w HID to a 1000w HID. What you said about accelerated metabolism makes perfect sense. Based on that, how much should I increase my feeding schedule, or should I even increase my feeding schedule?

 

[Bill284]

Ok thanks.

On this grow I switched from a 600w HID to a 1000w HID. What you said about accelerated metabolism makes perfect sense. Based on that, how much should I increase my feeding schedule, or should I even increase my feeding schedule?

In soil you still need a dry period.
So watering more often won't help if she hasn't eaten her last meal.
I run coco drain to waste.
With my lights turned up and a pot full of roots I feed every day.
Your best to weigh your pots to tell if they are empty.
Then refeed to run-off.
Higher temps and reduced humidity will increase the amount she processes daily.
Knowing when your pot is empty is key. For soil.


Stay safe
Bill284

 

[Trump]

Ok thanks.

On this grow I switched from a 600w HID to a 1000w HID. What you said about accelerated metabolism makes perfect sense. Based on that, how much should I increase my feeding schedule, or should I even increase my feeding schedule?

IMO, it really depends on the stage of their growth. Many people think that more is always better. Not always.

In veg the nutrient needs of the plant in volume are higher due to the physical plant tissue that needs to be manufactured by the plant processes, the main one being photosynthesis. Branches, roots and leaves take a lot of nutrient and light to grow. Once in flower, the physical cellular production is lower as the "growth" of the plant has shifted into flower production where the terpenes and natural oils that it is making along with the physical cellular structure of the flower itself are the priority. Way less cellulose to have to manufacture.

Personally, I reduce my nutrient solution PPM once I start to see pistil. In flower I've found that the amount of ions needed are less than in veg. It's more about feeding the right ion at the right stage of the plants growth cycle.

I use this as a general guide to when to adjust my feed ratios.

I'm a soil farmer. I normally don't go any higher than 1200ppm in my feed solutions in veg. In flower my max PPM is around 900 - 1000ppm.

@Bill284 is correct in that watering frequency is less important than the entire cycle of watering/dryback. I know it sounds redundant when I say that perfecting your watering practices will eliminate a lot of issues we face but I've found it to be stubbornly true. I've been vigilant in documenting my watering practices and making sure that I get full saturation throughout the entire media in the pot along with allowing for proper dryback before I feed again. Not only has this yielded me much healthier plants but I also don't get fungus gnats. If you've ever looked through the journal I currently have going you'll notice that I don't have any sticky traps in the tent. In fact, for the last couple years I've never had a bug or disease issue. I attribute that to how healthy I've been able to keep my plants. Bugs or disease, IMO, are a symptom of an unhealthy plant most of the time. Plants have their own defenses that they've developed over time but when they are sick or not at peak health those defenses diminish and allow the bugs to attack the plant at whatever weak point it can find.

Trump Growing Jan6 OG

Not really. Just thought it would be funny if there was a strain like that to grow!!🤣 Growing some Florida Strawberry clones I clipped off my mother. 11/15/2023 Temp - 81.5* Humidity - 58% VPD - 1.59 kPa DLI - 41 Leaf Temp - 80* Netted the girls as they were getting too tall and the branches...

www.420magazine.com

This is going to be a long post as I'm going to post the following. It is from another site that I frequent but we are not allowed to post links to other sites so I have to post the actual text. After I read it it answered a lot of questions that I was never really sure of but also made some things that I've observed make more sense.

I am not the author of the following:

This will be a long read based on my personal knowledge, opinions, research and others work to consolidate information for our members. I'm not presenting my opinions as facts so take from this what you like. I will be putting it in subsection format for easy reference.

First I want to make an important point to take into consideration before reading. The tap root will grow directly downwards to the bottom of the container before spreading out.

PERCHED WATER TABLE

What is it?

The perched water table is basically the height of the saturation zone where capillary action and gravity cancel each other out. This area will be saturated with water and will be responsible for most growers issues with watering practices especially in soil grows.

WHAT IS CAPILLARY ACTION

CAPILLARY action is is the combination of the cohesive and adhesive properties of water.

In short adhesion is water clinging to the media (think of it like wicking or soaking up)

Cohesion is where the water clings to itself.

So as the water is wicked up (adhesion) it pulls more water with it through Cohesion and at the point gravity and these properties cancel each other out is the perched water table.

This perched water table will always remain the SAME HEIGHT and will always stay saturated unless taken up by the plants or evaporates when the pot dries out. No matter the container height, depth or volume of media. So if a tall skinny container had a perched water table of 1" then a short wide one of the same media will also have a perched water table of 1". Which means the ratio of water to air in a wide pot will be higher than a tall skinny pot which will have a higher air to water ratio... keep this in mind as we get further.

Different media's have different perched water tables. A more absorbent media will have a higher perched water table than a less absorbent media... REMEMBER THIS as it makes a big difference on pot selection for your media.

DIFFERENT MEDIA

Water holding capacity is directly related to the height of the perched water table so soils with more clay or silt and less sand will have a higher perched water table than those with more sand because sand is a larger particle.

The larger the overall particles of the media the lower the perched water table and better the drainage.

By adding things like perlite or vermiculite (while vermiculite is good at absorbing water it also improves drainage so its helpful in keeping a more even level of moisture throught the media while increasing drainage due to its size) we can lower the perched water table by reducing the wicking (adhesion) ability and creating more space between particles overall reducing the cohesion effect and inturn the height of the perched water table.

Media's like peat based or coco have a much higher drainage and lower perched water table than soil and are therefore less susceptible to over watering but will require more frequent watering due to the lower water holding capacity.

Adding thing like perlite or hydroton to the bottom of the pots will NOT reduce the water table but instead raise it. This is because as I said the height of the water table will not change for a given media. So if you add things like that to the bottom you are essentially just moving the water table up.

Basically the larger the particles IN the media the better drainage and lower the water table.

If you want to see the height of your perched water table use a clear cup with drain holes fill with media and saturate it. Wait a few hrs for drainage and then come back and look. You can see the difference in the varying media's if you want to experiment.

If you feel you have over watered or your perched water table height is to high you can simply tilt your pot on a 45 degree angle and release more water from the media as runoff. To help visualize think of it this way if you have a perched water table of 2”. You can draw an imaginary horizontal line at that height, when you tilt the pot you have less media below that line and therefore you will have less water in the pot after tilting it.

POT SIZE

I have already covered this a bit but my opinion is if you are using a media with a higher water table you will benefit from taller narrower pots and if using a media with a lower perched water table the shorter wider ones may benefit you depending on your watering practices.

I prefer the taller over wider no matter the media as I choose to water often and have a higher air holding capacity and lower water table but that can work against you if you can't water as frequently and as plants grow it can greatly increase the frequency required as the roots will be pulling the water out of that saturation zone quickly. So you may want to use taller pots for small plants and transplant into a wider one as they grow.

You also don't want a pot that's too tall and the top portion of the media is drying out too fast while the bottom is wet.

Let's use seedlings as an example take a solo cup or a large container... the water table will be the same height in either. I see sooo often ppl trying to water a tiny bit in circles or mist the surface and for lack of other words IT DRIVES ME NUTS. Why because the roots are so shallow they are not at risk of being over watered. Remember though tap roots grow straight down so we need to be mindful as they grow depending on the gas exchange of the media that the majority of roots are not sitting in the saturated zone with poor gas exchange because this will cause lack of oxygen that we incorrectly refer to as overwatering which is actually the cause not the symptom.

It's important to fill containers to the top to give us a good amount of space above the perched water table that high in o2. If you fill a solo cup halfway with soil it's likely to be sitting in the saturation zone and will not do well.


Also going to make the point that plants will be most susceptible to overwatering when the roots first hit the bottom and spread out until they fill the bottom and start moving back up out of the saturation zone. So again it may be more beneficial to use a taller narrow pot for the early stages of growth (2-4 weekss depending on growth) and transplant into a wider pot as you go. After the transplant almost all of the roots will be above the saturation zone and it become much harder to over water. New roots will again work their way down into the saturation zone but you will have plenty above so its less likely to over water and why uppotting as you go I see as a benefit instead of starting in a large wide container.

POT MATERIAL

Some prefer plastic others fabric, air pots etc.

This can affect the perched water table by evaporation as the longer the exposed surface area the more evaporation that occurs from the media in say, fabric pots. This, imo, has a few benefits.... slightly reducing the perched water table but more so the exposure for gas exchange that's happening and that's a good thing for o2 levels in the root zone that I feel are directly related to growth rates and I'll explain why going a bit off topic for a second.

It's no coincidence that the fastest growing media's have the highest amounts of o2 and gas exchange.... for eg aeroponics have unlimited to rich o2 and water. Hydro similar with slightly less o2, soiless media's such as coco, and I would possibly include peat, and last soil. If you notice they are in order of growth rates and its not hard to see the difference in their air holding capacity in that order along with the fact that larger particles also have a better gas exchange rate. This is important because the plants take in oxygen and expell co2 in the rootzone as do the microbes on top of that so good gas exchange is important for both.

Just a note... air pruning has nothing to do with the benefits of fabric pots. All it does is signal the roots to grow in a different direction.

But let's get back on topic of watering and how it's affected.

TEMPERATURE AND HUMIDITY

The warmer the temps the more evaporation occurs.

The lower your humidity the more evaporation occurs

The more surface area exposed to air movement (wind) the more evaporation.

Think those don't need an explanation. But the difference in pot material coupled with these environmental factors will have an impact on your watering needs.

The temperature of the media not only affects evaporation but also directly affect the temperature of the plant and leaf temps. This has a large impact on nutrient uptake and transportation.

First let me say that this next part is opinion and I will gives my reasoning for my opinions. With the exception of hydro (leaving this part out as this post is about watering not hydro) roots like to be about the same temperature as the leaves contrary to what's talked about from many prominent growers in the industry but not all like Mr.Bruce Bugbee. IMO ideal root temps are the same as ideal leaf temps and overall plant temps especially since the root temps have a large impact on the plant and leaf temps. What are ideal temps imo and many studies show that leaf temps (NOT AIR TEMPS) of around 77f are most efficient. So how does a cool rootzone impact the plants negatively? Well it's 2 fold because of the cool temps the viscosity (measument of flow rate) of the sap will decrease so its harder for the plant to move the nutrients through the plant. The other is absorption and one fact is that in a cooler rootzone the concentration of nutrients is higher (but you just said it slows absorption?). Well, it does, as the nutrients build up in the roots it can absorb less and this has a direct impact negatively on the plant. It may appear to be overwatered because the plant is now struggling to take up and use oxygen. Add that to the slowed transpiration rates and you have the same symptom many refer to as overwatering which again is lack of o2. Now take a cold rootzone where the plants slow water uptake and then add the saturation zone to it and you can see the road to correction and recovery is a long one and can have huge impact on growth and yields.

So, get your pots up off the floor

WET AND DRY CYCLES

in soil and peat with higher water tables or with wider pots or combination of wet and dry cycles are important. This is to allow the dry back (including the uptake of water from the saturation zone) to prevent symptoms of over watering and help with o2 levels. Remember, the majority of roots will end up in the saturation zone with these media's or with wider pots. Which can become depleted of o2 quickly as gas exchange is lower in water and media made up of smaller particles. This is where pot size and shape are important for the size of plant. You have a small plant in large container and there is no way it can take up enough of the water in the saturation zone fast enough to get air exposure in a media that has low gas exchange and majority of the roots. So it's important to choose a pot size that will allow for this. It's also why using the finger method to gauge watering is poor and lifting the pots is much better. When they are light you know they have taken up a good portion of the saturation zone and are ready to be watered again.

This is much less of an issue when using soiless like coco or peat/perlite.