4 Weeks into Flowering. Fan leaves are slowly turning yellow at the base of the plant

[Monkybiz007]

Hello GC, I've got what I think is a problem and I'm hoping to get some peace of mind about it from you guys. I have a single plant that started on 12/12 lighting about 5 weeks ago. It is potted in soil, I haven't changed anything that I've been doing, and the plant had been going great until about a week ago. About last week, the fan leaves from the very first node at the bottom of the plants stem both started to turn yellow. This color change was consistant throughout the entire leaf, meaning it didnt start at one end and work its way to the other, the entire leaf underwent the color transformation at the same rate.

After the bottom two fan leaves turned yellow, they completely dried up and eventually fell off. I at first chalked this up to that node being too low to produce buds, and thought maybe the plant took care of its own unneccessary leaves. However, the two fan leaves coming from the next node up on the stem turned yellow two or three days ago. I'm no expert, but it doesn't take a genius to figure out that this thing is working its way up my plant. My question is, is this normal? I've done a fair amount of research on this and other Sick plants forums, and this doesn't resemble any of the common problems that come up. But, I did find one thread that said sometimes Cannabis plants do this in middle to late Flowering. I have never seen any of my plants do this before however, so I'm skeptical and scared for my plant! If anyone has seen this before, any advice/easing of fears would be appreciated.

[thefr3shone]

do you know how long your strain is supposed to flower for? if it is only an eight week flowering period then the reason this may be happening is because your plant is now using up all the nutrients it has stored up in its fan leaves in order to produce those big fat stinky buds from the way you described it (consistent color change, no new nutrients added etc.)

some pictures are always helpful to be sure and i'm sure a more experienced grower could give you a more definitive answer i was just giving my .02! good luck brotha

[Monkybiz007]

Thanks for the reply, +rep man. Unfortunately I don't know the strain so have 0 idea of what to expect in terms of flowering length, trichs have yet to start color change though, so I don't expect Harvest time to be right around the corner. I will try and upload pictures tomorrow, but the camera is of low quality. One poster on this board mentioned that leaves can turn yellow and fall off during early flowering because of a Nitrogen deficiency, but as I mentioned I have not changed the nutes, soil, or water over the last 5 weeks since switching to 12/12, and this problem just started a week ago. Would it be possible for a Nitrogen deficiency to take that long to show?

[Monkybiz007]

OK I finally got some pics up of whats happening.


I have stopped giving them fertilizer since about 5 days ago, figuring I would find out whats wrong before continuing feeding. I was using Botanicare Pure Plend PRO bloom once I put the plant on 12/12 about 5 weeks ago. I have used RO water the entire life of the plant, but I havent tested its pH yet. Could this be a pH problem from slow build up of the Botanicare in the soil?

EDIT: pH of RO water is between 6.0-6.5, Soil pH is between 5.8-6.3. However, I live in a very dry climate (Sonoran desert) so perhaps low humidity is creating a nutrient deficiency? Any advice on this would be great.

[SmknVTEC]

They need a little bit more nitrogen I think.