Help diagnosing brown/purple spots on lower leaves (veg)

[Franimal]

Seeing brown/purple spots on 6 week old indoor plants. Using a mix of coco and Promix under MARS ts1000 light. New growth is healthy and unaffected but have noticed the spots spreading to other lower leaves in the past week. One plant also has noticeable yellowing on lower leaves.
This only seems to line up with some of the symptoms of calcium deficiency and the soil ph is on the higher side close to 7.
If anyone has ideas please let me know. I’m not sure what else it could be.

 

[NorthernOrganics]

Looks hungry and thirsty. What are you feeding them and how often are you watering?

 

[mysticepipedon]

Seven is not a good pH.

 

[Franimal]

Looks hungry and thirsty. What are you feeding them and how often are you watering?

 

[Franimal]

Seven is not a good pH.

I know! We’ve been lowering the water/nutrient solution down to 6 but it hasn’t worked. Any suggestions? The soil itself measures as 7

 

[Franimal]

Looks hungry and thirsty. What are you feeding them and how often are you watering?

Hey there, just realized my message didn’t get posted.

They are about 5 weeks old and we only got proper lights on them two weeks ago.

watering - approx 2 cups water/half strength nutrients every 2 days. Solution is 6 ph

Just upped nutrients to full strength today.

I’m worried the ph is the issue causing uptake issues. Would you recommend watering with a ph of 5 or lower to get the soil ph down? Looking for any suggestions on lowering soil ph without overwatering or causing other issues. Would I want to flush the plant with low ph water or water a normal amount?

Any suggestions much appreciated

 

[mysticepipedon]

I know! We’ve been lowering the water/nutrient solution down to 6 but it hasn’t worked. Any suggestions? The soil itself measures as 7

The only thing you can do is lower the pH of the water or nutrient solution. It takes a while, because soil has buffer capacity and it's not always successful. I'd bring it down to 5.5 or so.

 

[Franimal]

The only thing you can do is lower the pH of the water or nutrient solution. It takes a while, because soil has buffer capacity and it's not always successful. I'd bring it down to 5.5 or so.

Would you recommend watering with a ph of 5 or lower to get the soil ph down? Looking for any suggestions on lowering soil ph without overwatering or causing other issues. Would I want to flush the plant with low ph water or water a normal amount? The plants are getting worse and I don’t know what else to do. Does this still look like ph issues to you?

 

[Pushrod Monkey]

Phosphorus deficiency and those nutes don’t appear to have enough for squat. Potassium either.

 

[mysticepipedon]

Would you recommend watering with a ph of 5 or lower to get the soil ph down? Looking for any suggestions on lowering soil ph without overwatering or causing other issues. Would I want to flush the plant with low ph water or water a normal amount? The plants are getting worse and I don’t know what else to do. Does this still look like ph issues to you?

There is a danger of overkill. I know, because I've done it.

Flushing in soil, for me, has never helped. It leads to overwatering issues and other nutrient imbalances.

Here's my guess, and it's only a guess — P deficiency makes sense. At a pH of 7, you will have a lot of calcium in solution, which takes phosphorus out of solution, so lowering pH is probably what you need to do. I have had mixed results, at best, in adjusting soil pH. It seems easier to bring it up than down.

 

[jguit]

You need to get control of both your pH and watering practices.

You need to be watering until at least 10% runoff and letting the media dry out some between waterings. Also, promix doesnt really care that much about pH going in but coco certainly does. I'd shoot for a pH around 5.8 to 6.1 and feed the correct strength of fertilizer. I'm not familiar with the fertilizer you're using but it looks like it should work.

You're not growing in 'soil', just to avoid confusion.

 

[Franimal]

You need to get control of both your pH and watering practices.

You need to be watering until at least 10% runoff and letting the media dry out some between waterings. Also, promix doesnt really care that much about pH going in but coco certainly does. I'd shoot for a pH around 5.8 to 6.1 and feed the correct strength of fertilizer. I'm not familiar with the fertilizer you're using but it looks like it should work.

You're not growing in 'soil', just to avoid confusion.

Hi and thanks for your feedback! How dry does it need to get between watering? And is it bad to use pH 5 water to try and get the soil pH down since it’s so high? The plants are going downhill quick and I’m scared to overwater but also scared they will get really sick soon
Would you suggest continuing to give nutrients every watering or alternate with low ph water?
Thank you

You need to get control of both your pH and watering practices.

You need to be watering until at least 10% runoff and letting the media dry out some between waterings. Also, promix doesnt really care that much about pH going in but coco certainly does. I'd shoot for a pH around 5.8 to 6.1 and feed the correct strength of fertilizer. I'm not familiar with the fertilizer you're using but it looks like it should work.

You're not growing in 'soil', just to avoid confusion.

 

[jguit]

Hi and thanks for your feedback! How dry does it need to get between watering?

Typically the containers will feel very light but not bone dry.

And is it bad to use pH 5 water to try and get the soil pH down since it’s so high?

Hard to say, no idea what's in your water or if it'll dilute your feed too much. I'd get proper pH down or use something like sulfuric acid if you dont have access to pH down. Obviously, you need to use caution and do a little reading before using sulfuric. I'm sure there's other ways to lower pH, try a search on the site.

The plants are going downhill quick and I’m scared to overwater but also scared they will get really sick soon
Would you suggest continuing to give nutrients every watering or alternate with low ph water?

If the pots feel light, I'd water until runoff and feed every watering.

Dont mess around with flushing the media, just get your feed pH sorted out.

 

[Franimal]

Typically the containers will feel very light but not bone dry.

Hard to say, no idea what's in your water or if it'll dilute your feed too much. I'd get proper pH down or use something like sulfuric acid if you dont have access to pH down. Obviously, you need to use caution and do a little reading before using sulfuric. I'm sure there's other ways to lower pH, try a search on the site.

If the pots feel light, I'd water until runoff and feed every watering.

Dont mess around with flushing the media, just get your feed pH sorted out.

I’m happy to report that ph is down to 6.5-7 and plants appear to be doing better. Once they are down to normal I was going to look at improving our nutrients. Because we are new we just started with the basics recommended by the local store but I am thinking it could be improved. Any suggestions to add to the current mix of nitro + grow and occasionally b1 boost? Cal-Mag? Do I need to add more phosphorus or will the normalized pH basically solve that problem?
Thank you!!

 

[jguit]

I’m happy to report that ph is down to 6.5-7 and plants appear to be doing better. Once they are down to normal I was going to look at improving our nutrients. Because we are new we just started with the basics recommended by the local store but I am thinking it could be improved. Any suggestions to add to the current mix of nitro + grow and occasionally b1 boost? Cal-Mag? Do I need to add more phosphorus or will the normalized pH basically solve that problem?
Thank you!!

It's hard to say without knowing what is in your nutrients or source water. It doesnt appear that you'd need more P though. Calcium? Probably.. Again, it depends.

 

[TryingToGrow]

Just water 5.5 ish pH

 

[Franimal]

It's hard to say without knowing what is in your nutrients or source water. It doesnt appear that you'd need more P though. Calcium? Probably.. Again, it depends.

Not sure if this helps?

 

[jguit]

With those numbers a little bit of calmag certainly wouldn't hurt if your using RO or low EC tap water. Your nutrients arent ideal but i'm sure they'll grow weed. @Pushrod Monkey is right, both PK are a little low in those nutrients.

I'd start around 4ml each (per liter) of part 1 and 2 with a little calmag if your water doesnt have it and take it from there. pH around 5.8. If your plants look hungry after a few days, increase the feed. Water around the edges of your pots until you get a nice amount of runoff. Don't water/feed again until the pots are light.

 

[jguit]

You can try running a little bit more of part 1 to compensate. Something like 5ml of 1, 4ml of 2 (per liter), and a little bit of calmag should get things a little closer. You'd have to experiment.

Mix it up and see where that puts your feed EC. pH to 5.8. Dilute it if the EC is too high.

 

[Franimal]

You can try running a little bit more of part 1 to compensate. Something like 5ml of 1, 4ml of 2 (per liter), and a little bit of calmag should get things a little closer. You'd have to experiment.

Mix it up and see where that puts your feed EC. pH to 5.8. Dilute it if the EC is too high.

Great thank you

another question….when do booster supplements come into play within the whole nutrient regiment? Is it okay to throw in some fish fertilizer or that kind of thing with feedings some days? What other nutrients or supplements are worth using?