Inter-veinal chlorosis in AllMix and CootMix potting soil

Question

The soil

Stage 1:

BioBizz AllMix with some additional Perlite. Around 50% as a total. AllMix is originally 30% perlite with mostly peat moss and some organic matter.

The containers were 2 gallon fabric pots.

The plants were feed with PH 6~6.5 water with Biobizz liquid nutrients.

Stage 2:

The container is around 75 gallons with 4 plants.

Transplanted ten days ago into a soil that is half a sort of Coot mix and half AllMix.

The "Coot Mix alike" part is:

• 1/3 coco coir
• 1/3 vermicompost
• 1/3 volcanic rock (Pozolana Balsalt)

I added 5L of Biobizz premix in the soil and top dressed with some other in small quantities such as seed meal, bat guano, Ecothrive Charge. A few spoons.

The soil has been heavily inseminated with Microlife, especially Micoryze, but all the range of usual micro organismes too.

The plants are watered With PH 6~6.5 water with some molasses and humic acid.

The soil itself has a PH around 6~7 depending on measurements.

The water pressure of the BlueMat digital moisture meter has been between 60 and 90, what is in the range of the manual for potting soil.

The plants

It is medical marijuana. I mean, really medical. Strains for chronic pain with lots of CBD that won't really make you high but a working extremely well on heavy wildspread chronic pain. This is of course under Doctor supervision.

The plants are Painkiller XL from Royal Queen Seeds. It is hybrids with Sativa dominance. This strain has a very good reputation. GrowWeedEasy quote it as one of the best high CBD strains.

The plants are in Vegetative stage, 6 weeks old. Around 1 foot tall.

Symptoms

The plants started to show sign of inter-veinal chlorosis in the 2 gallon pots quite early, around 3 weeks.

I tried to supplement with products containing micro nutrients without a success.

The veins are dark green and the rest is light green, in all the leaves from the upper half, at least.

Some leaves at the base are somewhat yellowing but nothing massive.

When I transplanted there initially was a transplant shock with dropping leaves and now the leaves are returning to a more normal shape. Except that now the chlorosis is far more visible.

Edit: actually more probably magnesium since it start from the bottom but could be several deficiencies as well. This exactly the same as on photos of Iron / Magnesium / Zinc deficiency symptoms you can see on internet.

I'm aware that these signs are not necessarily caused by actual deficiency. It can be caused by the interactions in the soil.

I don't really know where to start. With so many Basaltic rocks, with fresh PreMix and AllMix, the soil is not supposed to be lacking Iron.

It is probably a other thing that causes the iron deficiency. I'm quite new to the art and science of gardening I don't feel like I can make a reliable bet my myself.

Do you have some ideas or directions to help?

Answer 1

I normally see this kind of deficiency in alkaline soils where the uptake of iron and magnesium is limited by the soil pH being over 7. This reference is for outdoor plants but should apply to your case. A review of the symptoms points to a shortage of Iron, Manganese or Zinc in that order of probability.

I recommend spraying the plants with an iron chelate foliar feed. As this can be absorbed through the leaves it will go around the pH problems. Of course you will want to wash the leaves before harvesting.

The good old fashioned way is to provide more organic matter in the soil which should balance out all the things that have been added. Peat Moss is readily available if lacking in environmental sustainability. Compost is an excellent soil additive as well.