plants yellow.....1st ever grow....Help!!!!

story so far...... this is my first ever attempt at growing. the back 3 plants and front left have been grown from seed the front right came to us as an ophan.
i have 2 tents in a shed in the garden.

can some one please take a look at my pics and give me some advice.

all 5 plants are 7 and a half weeks into veg 18/6

the 3 plants at the back for the last 5 weeks have been under a 400w light. this light is a yellow/orange light.

the front left is the same strain (white widow/big bud) as the 3 at the back and i dont know the strain of the front right one.

these two have been under a 250w light since the begining of their life and this light is what i would call a white light.

i have fed and watered them all the same feed as and when required. and i have watered them with plain water and then a feed, bio bloom, alternately.

the 3 at the back have turned a yellow colour and have grown quite tall and the two at the front are a healthy green colour but shorter.

do you think this is because of the lights? or could it be something else?


i would also like to ask when should i turn them to 12/12?

also when i check the ph of a plant do i water plant with plain water and catch what runs out of bottom of pot to test? to be truthful with you i havnt checked the ph level as i was not sure what to do

has anyone got any solutions or is it too late to save the yellow ones?

it sounds like the 3 in the back need more light because a plant stretches when its lookin for light.what sort of light u using?

and put 12/12 when plant is 1/3 the size u want it and u should also check soils ph its very important your soil could be locking up nutrients causing leafs to yellow hope i helped good luck

Yellow leaves can mean a nitrogen deficiency. ph levels could be locking out needed nutrients. You can purchase a liquid pH tester for under $10. There are more expensive alternatives.

I always test the runoff water that comes out of the bottom of the container after watering the plants. For soil, 6.3 - 6.8 is most desirable. In my experience lockout happens around 5.5 or less and 7.5 or more.

AlanJ said:

story so far...... this is my first ever attempt at growing. the back 3 plants and front left have been grown from seed the front right came to us as an ophan.
i have 2 tents in a shed in the garden.

can some one please take a look at my pics and give me some advice.

all 5 plants are 7 and a half weeks into veg 18/6

the 3 plants at the back for the last 5 weeks have been under a 400w light. this light is a yellow/orange light.

the front left is the same strain (white widow/big bud) as the 3 at the back and i dont know the strain of the front right one.

these two have been under a 250w light since the begining of their life and this light is what i would call a white light.

i have fed and watered them all the same feed as and when required. and i have watered them with plain water and then a feed, bio bloom, alternately.

the 3 at the back have turned a yellow colour and have grown quite tall and the two at the front are a healthy green colour but shorter.

do you think this is because of the lights? or could it be something else?


i would also like to ask when should i turn them to 12/12?

also when i check the ph of a plant do i water plant with plain water and catch what runs out of bottom of pot to test? to be truthful with you i havnt checked the ph level as i was not sure what to do

has anyone got any solutions or is it too late to save the yellow ones?

Click to expand...

1st- buy a pH meter- keep your water between 5.8 and 6.3 - i stay at 6.0 -this means feed AND fresh water. Check your pH everytime, before every watering. Buy pH Up and pH Down and a dropper for easy pH changes.- when you water, check the runoff to double check and make sure your plant is where you want it to be.

2nd.Lighting- Are you using CFLs? You are going to want to switch the majority of them to cool white for flowering, 25% at most with the reds. If its HID it seems like u have a MH and need to change to HPS for flower.

3rd, Since WW and God bud are hybrids the plants could be showing their phenotype (traits) Some will be more indica dominant, some more sativa-the 1s in the back definitely look sativa. Alternately, it could also be the light-Red light encourages stem growth while blue encourages leaf growth.

They dont seem stretched to me, but it is hard to tell from here. *correction- there is a little too much space between nodes. it is a little stretched.

Lastly- you should have flowered a few weeks ago, about 12-18" is when you want to flower, You can prune off up to 50% without stunting the plant, I suggest topping it, and trimming off the dying leaves. Also after a week or so in flower, chop the bottom few inches off to get better air flow. I like to clip off new branches that form after the 5th week to avoid popcorn nugs. This also makes the nugs i have bigger. We all make the mistake of vegging too long, but it spends 8 weeks in flower, so u only need about 4 weeks in veg. hence the "12/12 when its 1/3 the height u want it"
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On to your main question- They need either sulfur, iron or NPK, depending on where it is yellowing. This could be from pH fluctuations locking out the S or Fe- NPK just means more fert. Its time to switch to flowering nutes anyways.

Use this link-its my favorite and very accurate and easy to diagnose.

http://www.greenmanspage.com/guides/tables.html