Bottom leaves rotting?

[Ohenry]

Hi all,

I have been growing my plants in doors with no signs of pests around. It was doing great until recently, I've been noticing the bottom/oldest leaves turning yellow and "rotting" until they fall off. I water only when needed (1-2/week), haven't added any additional ferts, and none of the other leaves seemed to be bothered.

Could it be due to the pot with no drainage even though I only water them enough to moisten the soil.

Thanks for the replies ahead of time!

Here are some of the pics:

http://imgur.com/hzQ5u68
http://imgur.com/Osy7Q8z
http://imgur.com/fhOcP2Y

 

[fertilizer]

No reason for concern, plants often abort their lower leaves, besides it's probably better for airflow around the plant anyway. 
Just keep on growing!

 

[JDFan]

That's just part of the plant lifecycle -- oldest leaves will die off and new growth will replace it - figure as the plant grows taller and has more of a canopy less light penetrates to the bottom portion of the plant so those lowest leaves have a harder time getting enough light and eventually no longer provide much for the plant so they die off rather than use more of the plants energy and instead the new growth uses that energy.