have in a grow tent a pineapple express 2 from g13 labs that is 6 weeks (box says 45 -50 day flower time) into flower and she is getting purple in the leaves on top and around buds … she also is getting some yellow fan leaves on the bottom … I am using general hydroponics with pro mix microactive soil … the colour started about 10 days ago … feeding at half strength with ph 6.00 and ppm 639 for last few feedings cause I had some cupped up edges on fan leaves and thought i might be overfeeding … night temp about 12 - 13 c (53 - 55 f ) … day temp 20 -22 c ( 68 - 71 f)
drainage ph 5.83 and ppm 951 … hoping to flush for harvest in about 4 to 7 days … are the purple and the yellow fan leaves cause to worry and what could be causing it
The yellowing leaves are typical near the end of flowering, although yours are pretty advanced. The plant is hungry and using its leaves up.
I grow in soil, but your ppm seems low.
The purpling is probably due to your cool temps.
I was feeding at full strength but had leaf edges curling up so I reduced
nutrients to half in case I was overfeeding … but I have started increasing them today to about 3/4 strength …should I increase nitrogen for the yellow
… waiting for amber trichomes to flush for harvest
You’re pretty far into flower. I wouldn’t add extra nitrogen. I can see the burnt tips.
Just proceed as you are. They’re going to get ugly before they finish, but who cares about that. 
you are right on the burnt tips … will do as you say … wasn’t sure if I needed to change something because of the colours … first grow and a little nervous at this stage … thanks for the advice Drinkslinger
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You still have active pistil production so you still have 3 weeks or so to go IMO. The nutrient lines generally don’t provide N so you start to see all of the deficiencies. Canoeing of leaves like that when they become yellow and somewhat brittle is very common. This is normally what most growers look for.
Night time temps are low. If you could bring that up in the future it would be good. I like PH 6.0 in Promix though I haven’t used their soil; just Promix.
Your runoff TDS indicates the plant isn’t using your nutes at 600 ppm. I would likely stay where you are for now. A couple of other things to look at now: any pests? You will need a loupe to tell. If you see any ‘webbing’ showing around flower, that’s an indication too.
What nutrient line are you using?
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the leaves were healthy green colour when they curled up , it was only a few leaves … trying to keep soil ph around 6.0 but it seems to want to be lower , had an issue with low ph about 5 weeks ago and had to raise ph of nutrients to 6.2 to keep soil ph up … flushed with water at ph 6.0 about 3 weeks ago and drainage was 82 ppm … feeding on april 18th had drainage ph 5.91 and ppm 896 … take plant out of tent to feed her and check her and haven’t seem any sign of pests … humidity in tent is about 42 % … am using General Hydroponics 3 part Flora series … will bring night temps up a few degrees and keep nutrients at half strength…
included a pic of trichomes for your opinion on when she may be ready to flush (if you don’t mind) thanks for any help …
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The white pistils are a good indicator you have some time left. It’s putting on the frost for sure but you don’t want to lose out on the last couple of weeks of bulking up. They will almost double in size.
Sounds like you are doing everything correctly. You still have some time. Tag me in as you go and I’ll help if I can.
really appreciate help … will update post … new to forums… not sure how to tag someone …
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Just add the @ sign ahead of their name.
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@Myfriendis410 … quick update … raised night temps to 15c (59f) and feeding at just over 1/2 strength with ph 6.1 and ppm 664 … drainage is ph 5.83 and ppm 951… she is maturing nicely and purpling on leaves is a little darker … removing a few very yellow fan leaves from bottom of plant but otherwise she appears healthy … found 3 or 4 amber trichomes and am watching closely for more …
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It sounds like you are in the right place with your plant. Very nicely bulking up!
Do you have a loupe or microscope for looking at trichomes? You’re gonna need it soon.
@Myfriendis410 … have 40x loupe and watching closely … hoping to flush in several days … will update again later … thanks for the help
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Looking good.
time to update progress @Myfriendis410 @Drinkslinger … was keeping things the same and watching for more trichomes … leaves on top are getting darker but dont seem to be dying … fan leaves going yellow
… have been feeding her every 3 or 4 days for months now , always the same … last time at 3 days she was only half dry … checked next day and she was still the same so I gave her a lite feeding and the drainage ppm was almost 1200 … thinking it could be nutrient lock … I had a good look for amber trichomes and found more so I decided to flush her and get her ready for harvest in 2 weeks … hoping I made the right choice … thanks for the help … will update
before I forget again I wanted to update my post on how my plants finished …… continued with same nutes for 2 weeks until I had some amber trichomes and then flushed and gave only ph 6.0 water for 2 weeks until harvest … finished with 5.5 ounces (dry weight) of really nice bud … pleasure to smoke … friends call it happy weed …… thanks for the info it sure helped get make this grow a success @Myfriendis410 … @Drinkslinger
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This pic to me looks like some heat damage. The curled edges. I could be wrong though.
The most common causes of cannabis leaves turning yellow are nutrient or environmental factors, but there are numerous other possibilities. I recommend reading our article on why your leaves are turning yellow to find a quick solution!