HELP! Leaves dark, dull slight purple tinge, yellow tips

[konsta]

Hi, it's my first post. I'm in Australia, I hope you are all well and staying safe.
I have 2 plants, Northern Lights feminized seeds under a 75w LED from A Pot For Pot hanging 60 cm (24") above the plants. The pots are 20 cm (7" to 8") with premium potting soil & pH around 6.5 to 6 for both. I'm comfortable with the watering - been using a meter to check. Planted with slow release fertiliser, seaweed soil supplement added (sparingly & according to instructions) during vegetative stage. Liquid potash added in 1st and 4th week of flowering stage. Now just beginning week 7 of flowering, buds developing but a bit slow for my liking (vegetative stage was 16/8 hours light cycle). One plant recently starting to show duller leaves and yellowing in the tips and edges. I am thinking either nutrient stress or maybe copper deficiency as there is a dark almost purplish tinge to the duller leaves.
Does anybody have any ideas?

[Gingerbeard]

Hey konsta . You're good. By week 7 of flowering, many plants do this. It's like autumn for the plants when all the goodness is getting sucked from the leaves and all the energy is going to make buds. Technically, sort of, you have all the nutrient deficiencies that affect leaf growth. Which is usually bad.
Don't fret if you see leaves going all sorts of pretty colors, crisping, and falling off. It makes for an easier harvest. Fewer leaves to cut.
Keep up with the bud porn!

[konsta]

Thanks heaps, Gingerbeard, that's reassuring It's only the one plant and only on a few upper leaves. But I'm not sure what you mean "you have all the nutrient deficiencies that affect leaf growth. Which is usually bad." Do you recommend I cut off the damaged leaves?

[Gingerbeard]

Your plants are doing what some plants do at the ends of their lives. All their energy is going into bud development and the leaves are not getting anymore nutrition. The leaves are cosmetic, at this point. You can leave them or cut them off. Your plant will be dropping them. I leave them because I like the colors.
There is information on temperature, pH, calcium, and plain ol' strain causing the color change and is available all over the GWE website. The basics are above. You can do your own in-depth research. Of two seeds from the same mother plant, one may grow completely different than the other.
Your next question will probably be about when to harvest. Take a look at the following link. The best answer is that the best time to harvest comes with experience.

When is the Best Time to Harvest Marijuana Buds? | Grow Weed Easy

[konsta]

Thanks again and thanks for the link. Actually I'm OK with when to harvest. In my 70 years on the planet I have brought a few crops to harvest but this is my first indoor effort. I was curious about why one plant was developing discoloured leaves and not the other when both had been treated exactly the same. I hadn't seen this extent of variation on outdoor plants before. But your post answered my questions. It's just great to get useful information from someone on the other side of the world. The second plant's leaves are now yellowing and I understand all the nutrients are going into the buds. Both girls are doing well.
Thanks again, Gingerbeard.

[Gingerbeard]

Carry on...