What's going on with my plants?!

Pants are in 65 gallon smart pots outdoor in "super soil" mix. I water them every 2 or 3 days as needed. All plants have the exact same growing conditions and are exhibiting the exact same issues. Its a little hard to tell from the photos of the inside of the plants because I've been picking off the sick looking leaves but it starts on the lower/inside leaves and is slowly working its way up the plant. Leaves are turning lighter and getting splotches on them and then eventually turn yellow/brown and they die/fall off the plant. Also growth has slowed down/stunted. I've looked around the internet and haven't been able to really pinpoint the issue. I thought it was maybe a phosphorus deficiency so I've been adding a product called "Mammoth P" every watering but that only seems to have slowed it down a little. The PH of the soil is around 7 (yellowish green). I don't know exactly what it is since I only use the general hydroponics PH control kit you get at the store. Its not a huge issue right now but I want to nip it in the bud before it becomes a bigger problem.

Why would Mammoth P address a potassium deficiency? You say super soil - that you made or bought? What was added for potassium?

Sorry lol, I meant a phosphorus (P) deficiency. I made the super soil myself and only filled the containers about 1/2 with the concentrate then filled the rest with base soil (roots organic). Sources of phosphorus include bat guano (0-7-0), bone meal (3-15-0), and fish bone meal (3-16-0). The mammoth P is a liquid microbe inoculate that's supposed to help digest/unlock the slow release sources of phosphorus and from what I hear it works really well. I've been using it at 1 ml per gallon of water but like i said, its only seemed to slow it down a little which makes me think Im on the right track but still not out of the woods yet.

Hello Flypaper,

From those distinctly yellow leaves, id say its slightly Nitrogen deficient.
Followed by slightly Potassium deficient.

I think you could do with amending your topsoil.
Do you have any "blood and bone", and some wood ashings?
Id say try this mix. Top dress the plant with it. Then give your plant a mulching.
"Premium Blood and Bone" will contain added potash. So if you have premium. Skip the wood ashings.

Basically, i just think you need to fertilize. How long since you did so?

Garden looks good,

Tim.

Thanks everyone! I'll pick up some blood and bone this weekend and try dressing up the topsoil. Im pretty sure I have some fox farms grow big laying around somewhere which is 6-4-4. Maybe I'll try adding some of that with the mammoth p until I can pick up some some more supplies this weekend. I haven't been feeding them at all really. The super soil is loaded with all sorts of goodies and they usually do just fine without me adding any extra fertilizers besides some compost tea once every 7-10 days.

hotrodharley said:

Why would Mammoth P address a potassium deficiency? You say super soil - that you made or bought? What was added for potassium?

Click to expand...

I agree its K deficiency. This will get worse and you will lose final weight. Those big girls need extra feeding, get some potash in there, and foliar feed with liquid potash for a month.