Soil PH or Nutrient Issue?

[johnmartin3219]

Hello,

First time grower and poster so please forgive me!

I've noticed some signs of deficiency on my plants over the last few days (see attched images). I've read some stuff online based on the leaves (e.g not enough CalMag or Phosphorus) but I'm now a bit confused

Also I've been growing for 7 weeks and I'm not sure if they are the right size? I was under the impression they should be bigger + flowering by now. I've only just bought a soil PH reader so not sure if my soil was a bit too acidic?

Here are a few details.

Strain
Auto White Widow

Conditions
Growing Outside
70% Multi-purpose compost 30% perlite
30L Fabric growing pots

Soil PH
5.5-6

Feeding
1ml/L Grow - General Hydroponics
1ml/L Micro - General Hydroponics
1ml/L Bloom - General Hydroponics
1ml/L CalMag

Amount
1L Per Plant
1-2 times per week

Any help would be much apreciated

Thanks for your time.

 

[MIAutomatic]

Your PH is low, and that is a lot of compost. It’s not generally recommended to use more than 1/3 compost in a soil mixture. Do you have any idea what the nutrient values of the compost are? My guess is it’s too hot. I bet those roots have been searching for some milder soil and have finally given in to the high nutrient levels in the compost. It would explain the lanky appearance combined with nutrient burn/lockout.

 

[Del boy]

Hello,

First time grower and poster so please forgive me!

I've noticed some signs of deficiency on my plants over the last few days (see attched images). I've read some stuff online based on the leaves (e.g not enough CalMag or Phosphorus) but I'm now a bit confused

Also I've been growing for 7 weeks and I'm not sure if they are the right size? I was under the impression they should be bigger + flowering by now. I've only just bought a soil PH reader so not sure if my soil was a bit too acidic?

Here are a few details.

Strain
Auto White Widow

Conditions
Growing Outside
70% Potting compost 30% perlite
30L Fabric growing pots

Soil PH
5.5-6

Feeding
1ml/L Grow - General Hydroponics
1ml/L Micro - General Hydroponics
1ml/L Bloom - General Hydroponics
1ml/L CalMag

Amount
1L Per Plant
1-2 times per week

Any help would be much apreciated

Thanks for your time.

Hello is your pot 30 Ltr and you only giving it 2Ltr a week the pot is prob dry in the bottom and in a pot that size i would have not added calmag unless the plant needed it which i doubt it did. your ph is to low soil PH should be in between 6.0 to 7.0
and yes for 7 weeks they are a bit small

 

[johnmartin3219]

Your PH is low, and that is a lot of compost. It’s not generally recommended to use more than 1/3 compost in a soil mixture. Do you have any idea what the nutrient values of the compost are? My guess is it’s too hot. I bet those roots have been searching for some milder soil and have finally given in to the high nutrient levels in the compost. It would explain the lanky appearance combined with nutrient burn/lockout.

Thanks for your reply. Whoops I didnt realise you weren't suppose to use all potting compost. I'm not sure about the nutrient values but will try and find out.

Whats the right mixture? Could I add some top soil to dilute the potting compost or would it be bad to repot them at this stage?

 

[johnmartin3219]

Hello is your pot 30 Ltr and you only giving it 2Ltr a week the pot is prob dry in the bottom and in a pot that size i would have not added calmag unless the plant needed it which i doubt it did. your ph is to low soil PH should be in between 6.0 to 7.0
and yes for 7 weeks they are a bit small

Thanks for your reply.

Yes just 2 Litres at the moment. Although I've been testing with moisture probe and it seemed to stay between moist/wet most of the time.

Bascially I was worried that I was overwatering (as the pots would never dry out and could see some yellowing/dropping leaves) so wanted to keep it precise.

Just out of interest how much water should I be giving at this stage? Again the articles online were a bit conflicting

Ah right ok. I was under the impression autos needed CalMag.

Whats the best way to rasie the soil PH?

 

[MIAutomatic]

Thanks for your reply. Whoops I didnt realise you weren't suppose to use all potting compost. I'm not sure about the nutrient values but will try and find out.

Whats the right mixture? Could I add some top soil to dilute the potting compost or would it be bad to repot them at this stage?

Adequate air in the soil and eventually the root zone is one of the most important keys to success. Compost is usually pretty heavy stuff. A good mix is: 1 part compost 1 part drainage (perlite, vermiculite, rice hulls etc.) 1 part peat or coco (coco is lighter than peat, so using coco will allow you to add a bit more compost if you choose).

Topsoil is also pretty heavy stuff and wouldn’t add much aeration. I think you just need to make it work for this grow use a lighter mix next time. I would buy a trusted brand of premixed soil or peat mixture. Coast of Maine is great for soil and Promix and Biobizz make great peat based mixes. If your goal is to do living soil, that’s an whole different thing and I am not the guy for that.

All marijuana plants need calmag, autoflowers are no exception. Soil or compost tends to contain plenty of it naturally and many mixes are pre-charged with enough for most of if not the entire grow cycle. Regular calmag is part of most coco nutrient brands, but should only be added as a supplement when needed in soil and peat based mediums. Getting a good understanding of your base inputs will help to bring this into focus a bit more. You were just adding something your soil already had plenty of in this case.

good luck!

 

[Del boy]

Thanks for your reply.

Yes just 2 Litres at the moment. Although I've been testing with moisture probe and it seemed to stay between moist/wet most of the time.

Bascially I was worried that I was overwatering (as the pots would never dry out and could see some yellowing/dropping leaves) so wanted to keep it precise.

Just out of interest how much water should I be giving at this stage? Again the articles online were a bit conflicting

Ah right ok. I was under the impression autos needed CalMag.

Whats the best way to rasie the soil PH?

Hello if i was you i would tag Man o green he is the one who can give you better advice on soil then me as i grow in coco he will put you on the right track for sure

 

[johnmartin3219]

Adequate air in the soil and eventually the root zone is one of the most important keys to success. Compost is usually pretty heavy stuff. A good mix is: 1 part compost 1 part drainage (perlite, vermiculite, rice hulls etc.) 1 part peat or coco (coco is lighter than peat, so using coco will allow you to add a bit more compost if you choose).

Topsoil is also pretty heavy stuff and wouldn’t add much aeration. I think you just need to make it work for this grow use a lighter mix next time. I would buy a trusted brand of premixed soil or peat mixture. Coast of Maine is great for soil and Promix and Biobizz make great peat based mixes. If your goal is to do living soil, that’s an whole different thing and I am not the guy for that.

All marijuana plants need calmag, autoflowers are no exception. Soil or compost tends to contain plenty of it naturally and many mixes are pre-charged with enough for most of if not the entire grow cycle. Regular calmag is part of most coco nutrient brands, but should only be added as a supplement when needed in soil and peat based mediums. Getting a good understanding of your base inputs will help to bring this into focus a bit more. You were just adding something your soil already had plenty of in this case.

good luck!

Thanks for your reply. Yeah sure that makes sense.

Just a quick follow up on the soil. I've just found out that it's multi-purpose compost not potting compost (my apologies!). Also it says there is already a high level of peat in it? (see attched images).

So should I stop using CalMag completely? also should I reduce my added liquid nutrients?

 

[johnmartin3219]

Hello if i was you i would tag Man o green he is the one who can give you better advice on soil then me as i grow in coco he will put you on the right track for sure

Ok thanks. How do I tag someone?

 

[Del boy]

Ok thanks. How do I tag someone?

Hello @johnmartin3219 like that