Struggling to figure this problem!

Welcome to Percy’s mate.

Quick glance would say it sure looks like a calcium deficiency. Calcium deficiency can be caused by several things. First of course would be the absence of sufficient calcium. Next could be lockout caused by either PH imbalance or nutrient imbalance. The easiest way to go is to give us some more information. What strain are you growing, what are you growing in soil or coco, what nutrients are you using if any, how much nutrient are you using, what is the ph of the water/feed, what is the input EC of the water/feed? This will give us the information we need to help you succeed in the grow

@monkeydo

Hi monkeydo! Thanks for the helping hand! The strain is green gelato autoflower from royal seeds and the medium is biobizz allmix (soil). biobizz root juice 4ml/litre on day 21 and 0.7g/litre of biosy and 1ml/litre biobizz grow the following water. Watered with water 2 days ago but issues have worsened. Was day 31 time of photo. Unsure about pH of water, first water was raining water so pH should be near neural however the following water was chlorinated (hard water in my area - if this helps) and rain water for the last. No info about ec as do not have a ec meter :/

It definitely looks like a nutrient deficiency. I would recommend picking up a pH pen and pH test  your water.  That is probably the best place to start.  As it will give you a baseline to work with. As  @monkeydo said it would definitely help to know what medium your growing in.  When I have  nutrient issues I usually flush the plant then give it some Advanced Nutrients: Revive.  It helps repair sick plants and has worked for me really well. 

@mediamaster

The medium is soil, biobizz allmix. Gave the plants a flush the last time I watered them (2 days ago) and will pH test the water ASAP and get back to ya! Will defo check out the nutrients you've suggested

Yer man, ph can definitely cause things like this and if you are going to keep growing for a while the ph pen is a small investment in a quality harvest. Of all factors, the input ph is super important to growing high quality cannabis. You can also be looking at lockout and the pots might benefit from a good flush right now. The flush helps remove any unwanted residue from the soil and let’s your plants eat and drink easier.

@monkeydo

Really good to hear the plants are improving. Lower grower stress equals a better result every time and we can probably improve your grow even more. You would probably benefit from adjusting the ph of your water/feed. Cannabis plants preform best in a relatively narrow ph zone for top growth but will survive in a much wider range but you can loose yield and potency. For Cannabis growing in soil try to aim for ph 6.5. If you are growing in coco or any hydroponic situation aim at ph 5.8 to 6.0. If the ph of your input isn’t good it can cause lockout and deficiency in some nutrients like calcium among others. Start with correcting the ph, keep an eye on the plant and post weekly updates if you can. Members here will help you reach the harvest and we all get to learn in the process. It’s what Percy’s does brother.

@highsnackz I grow using BioBizz Light mix and the BioBizz Nutrients and Supplements.

Can you tell us your temps in the grow area, the soil and water? What is your RH?

In my experience, as far as I can tell, I agree with the above mentioned assesment. It seems to be more of a pH problem than a deficciency in nutrients.

Also have you read about using mycorrhizal fungi. Inoculated roots with micorrhizal fungi can tolerate better all sorts of extreme situations and I again in my personal experience I can get 100% before that statement

In any case 0,8ml/L CalMag may be way too much. Pay attention to that since the problem seems to be pH. I think I would try to sort that out first.

Happy growing brother and may your smokes be dank and blue!