How much time do I have left and what's wrong with the bottom leaves?

[destinianto]

hi guys

this is first grow, my first plant is 45 days old sativa dominant autoflower in soil under 20/4 led light with AN gmb nutes.
I started to feed her big bud cal mag and some b 52.
she's going pretty pretty but I dunno whats wrong with bottom leaves? does this plant look healthy? and how much time should I left for harvest usually? And depending on its looks now(1.5 foot tall) how much should I expect to yield from my plant?

high regards

 

[Lockiou]

I give it another 3 week till harvest. I see one leaf with issue. It looks like calmag. I would add a bit.

 

[BuddroGreen]

Normal for the bottom fan leaves to die off late in flower as the plant uses the resources from those leaves as energy, or it can be from low light as well. Get yourself a pocket microscope w/LED or jewelers loupe w/LED to look at the trichomes on the flowers, the only true way to tell if the plant is ready for harvest is by studying the trichomes.

Pictures on when to harvest - Trichome colours

 

[Emilya Green]

I see strong signs that you are overnuting a bit... back off on the nutes by 50%... see if that clawing goes away and burning of the leaf tips stops progressing. If you are not alternating nutes and water, do so.

The lower damage looks like a magnesium deficiency... calmag can help... IF and ONLY IF you have your pH adjusted correctly. Adjust your pH to 6.5 whether it is nutes or just plain water, and your problem may stop progressing without adding anything else. The leaves showing damage now have been cannibalized for their stored up magnesium... they will never recover. Your goal is to keep this from progressing up to the new growth.