pH Issues? Worm casting impact?

petroleumboy · Jan 9, 2021

Hi, my first post on forum so please be gentle with me :)

I'm just getting into flower, with three Hindu Kush. I'm starting to see more and more leaf issues and went to my local grow supplier yesterday. Unfortuntately the grow advice I got from the local shop was the opposite I got on one of my last visits, so I thought i'd post and see if anyone validates his recommendation.

Growing in a medium of 60% ProMix HP / 20 % worm castings / 15 % perlite plus other minor amendments. Indoor grow.
I've been trying to keep my pH in a range of 5.8-6.4 as I was told this medium is to be treated as "soilless"???

My local shop-keep seemed to think I need to buffer my soil, due to what he called "low pH associated with worm castings" (from what i've read in other postings here, worm castings are relatively neutral so i'm not sure if I should trust him or not?). Regardless, his recommendation was to attempt to bring up my pH a bit with gypsum sprinkled on top and watered in.

The last time I tested my outflowing water, I had an input pH of 6.2, and an outflow pH of 5.5.

Questions:
1) Am I a soilless grow with this medium?
2) Are worm castings commonly thought to be acidic and a pH lower-er?
3) Based on my leaves, do people concur I have a pH issue?
4) Recommended pH for my medium?

Thanks in advance to all who provide some insights based on their experience!

PK1 · Jan 9, 2021

welcome to farm @petroleumboy here is a chart to give you better understanding of plant deficiencies. I'll try to guide as much as i can. I do use promix hp. I don't add worm casting to it due to the nutrients i use. are you feeding anything else except water and the worm casting that you've mixed with your promix? What type of ph down are you using? What is your tap water ph and ppm?

chemistry · Jan 9, 2021

What PPM are you feeding at? Are you feeding your plants flower type feeds, as apposed to veg feed, as their needs change during the flowering stage.

petroleumboy · Jan 9, 2021

Good questions PK1 and chemistry.

I've been feeding since about 2-3 weeks post germination. I switched fertilizer about a week or so after flowering started. All of my chem products are rebranded by my local grow shop so i've got no info on there origins.

Both veg and flower fertilizers are two part. 1-2-5 and 2-0-0 for veg and 2-0-0 and 0-4-4 for flower.
Brand on my pH down is unknown.
Tap water is about 170 ppm and allowed to rest for a few days before adjusting pH (7.1 pH). I was running CalMag at about 4mL per gallon which would bring my water up to about 320 ppm. Tap water rested plus CalMag was bringing me down to around 6.6pH

@chemistry, I don't think i've checked my ppm of my fertilizer but will the next time I make up a batch...

petroleumboy · Jan 9, 2021

Strain - Indica Hindu Kush
Number of Plants - 3
Grow Type - Soil
Grow Stage - Flower
Bucket Size - 5 Gallon synthetic fabric bag
Lights - Mars Hydro TS@2000 280W at 18" height
Nutrients - Feeding for flower (2-4-4 @ ~4mL/L)
Medium - 60% Pro Mix HP 20% Worm Casting 20% perlite
Water PPM with CalMag - 320
PH - 6.5
Humidity- 45%
Room Temperature -78
Solution Temperature -72
Room Square Footage - 3X3X6
Pests - None

PK1 · Jan 9, 2021

Your ph down bottle, Read and find out what type of acid it is?
What is your tap water ph and PPM?>
I can see why you have had nitrogen burn marks. cal-mag, part 1+2 also carry nitrogen.

how much of what bottles did you give last feeding?

chemistry · Jan 9, 2021

170 out of the tap is ok, you need to drop the calmag and up your flower nuits up to around 650ppm, this includes the 170 for your tap water. PH your water to 6.0 with the PH Down, and you should be sorted. Don't let your medium dry out.

petroleumboy · Jan 9, 2021

PK1 said:
Your ph down bottle, Read and find out what type of acid it is?
What is your tap water ph and PPM?>
I can see why you have had nitrogen burn marks. cal-mag, part 1+2 also carry nitrogen.

how much of what bottles did you give last feeding?

I'm shocked to say that my acid doesn't say what kind it is.
Tap water is 7.1-7.5 pH and 160-180 ppm
Fertilizer solution would look like this:

1.5 L water
4 ml/L of Part II and Part III
4 mL/g of CalMag
pH adjusted for range of 5.8 to 6.4

petroleumboy · Jan 9, 2021

chemistry said:
170 out of the tap is ok, you need to drop the calmag and up your flower nuits up to around 650ppm, this includes the 170 for your tap water. PH your water to 6.0 with the PH Down, and you should be sorted. Don't let your medium dry out.

Thanks @chemistry. I'll head your advice on the CalMag as @PK1 also suggested it might be contributing to some nitrogen burn. Would you suggest I also dust the top of my pots with the gypsum before my next watering? Provide some calcium?

PK1 · Jan 9, 2021

petroleumboy said:
I'm shocked to say that my acid doesn't say what kind it is.
Tap water is 7.1-7.5 pH and 160-180 ppm
Fertilizer solution would look like this:

1.5 L water

4 ml/L of Part II and Part III

4 mL/g of CalMag

pH adjusted for range of 5.8 to 6.4

i use promix hp, tap water ph is at 7.02
When i add my nutrients my water ph drops to 6.4
I don't ph adjust because promix adjusts the ph to 6. Slurry test results will show that

What you need to find out is tap water ph, once nutrients added, measure ph and then adjust ph to 6.3
5.8 is for coco and hydro. If the ph of water after nutrient is around 6 to 6.5 than just leave it and don't ph adjust. However, if your ph jumps up after nutrients than adjust ph to 6-6.3

petroleumboy · Jan 9, 2021

PK1 said:
i use promix hp, tap water ph is at 7.02
When i add my nutrients my water ph drops to 6.4
I don't ph adjust because promix adjusts the ph to 6. Slurry test results will show that

View attachment 1077443

What you need to find out is tap water ph, once nutrients added, measure ph and then adjust ph to 6.3
5.8 is for coco and hydro. If the ph of water after nutrient is around 6 to 6.5 than just leave it and don't ph adjust. However, if your ph jumps up after nutrients than adjust ph to 6-6.3

Thanks @PK1. I"m doing pretty much all of that, with the exception being i've let my pH of water or fertilizer drop as low as 5.8. Based on your comments above, is it fair to say your treating my medium as being "soil"? Many seem to suggest that a medium based on being upwards of 2/3 pro mix as being a soilless medium. Sorry to keep harping on this, but this was one of my key questions in this thread....

PK1 · Jan 9, 2021

yes, tread promix hp like soil. Don't overwater and water properly to runoff

petroleumboy · Jan 12, 2021

PK1 said:
i use promix hp, tap water ph is at 7.02
When i add my nutrients my water ph drops to 6.4
I don't ph adjust because promix adjusts the ph to 6. Slurry test results will show that

View attachment 1077443

What you need to find out is tap water ph, once nutrients added, measure ph and then adjust ph to 6.3
5.8 is for coco and hydro. If the ph of water after nutrient is around 6 to 6.5 than just leave it and don't ph adjust. However, if your ph jumps up after nutrients than adjust ph to 6-6.3

@PK1, can I ask, when you feed, how do you determine you fluid (water and fertilizer) volume? At this stage, i'm typically watering about 2.5 liters of water per plant. Would you fertilize at the same volume? Thanks in advance!

PK1 · Jan 12, 2021

i determine it by looking how green my plant is and what my ppm levels are. my tap water has 22ppm
seedling 22 - 300
Veg 300 to 600
flower 600 to 800/900/1000 depending on your strain.
as far as how much water, i water until i get run off. However, my watering takes about 1 hour. Thats a combination of 1 min watering and 15 min of waiting lol.

petroleumboy · Jan 13, 2021

PK1 said:
i determine it by looking how green my plant is and what my ppm levels are. my tap water has 22ppm
seedling 22 - 300
Veg 300 to 600
flower 600 to 800/900/1000 depending on your strain.
as far as how much water, i water until i get run off. However, my watering takes about 1 hour. Thats a combination of 1 min watering and 15 min of waiting lol.

YOur much more patient than I am pal. I trust your special ladies appreciate the efforts

PK1 · Jan 13, 2021

petroleumboy said:
YOur much more patient than I am pal. I trust your special ladies appreciate the efforts

having couple joint's rolled up helps. during the brake light one up and go through each plant to see what its showing you.

pH Issues? Worm casting impact?

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