Questions of a new grower

[Limolax]

Hi everyone. I am new grower and trying to figure out the way to grow indoor in very small scale. I am doing my 3rd attemp this time. The two previous ones failed miserably. That's a different story and compelitely irrelevant since I am using different method and growing medium. Here are my questions. Some are general but if you need more info about my grow there is a link on the bottom on my signature.
1- What exactly happens if I veg and bloom with just MH lamps no HPS? Or what are the differences?
2- Is it ok to add more soil on top of the pot every once in a while? I mean doesnt it hurt the plant if I berry a small bottom part of the stem under soil?
3- The leafes on the bottom of my plants are getting pale, yellowed and dried. I know it's normal for plants to lose leafes in their life cycle but here are couple of pictures. The yellow leafes are the 3rd set. 1st and 2nd got yellowed slowly and dried and fell down.
The plants are 5-6 weeks old. Been vegging in real soil plus organic materials. The light cycle is 20-4. They look Ok to me but as I explained I am a newbie in this field. Here are some pictures taken today.

By the way the plants have been repotted yesterday into thise new pots.

 

[Scrappy-doo]

Hey Limolax! The difference with MH vs HPS is how the plants grow. They'll tend to be bushier and tighter with MH and will stretch more with HPS. Plenty of people use just MH so no problem there.

You can definitely add soil to the top. I do that if they are drying out faster than I'd like them to, or when I top dress I'll sometimes also add soil on top with it.

Yellowing/fading leaves on the bottom mean your plant is hungry. Transplanting into a larger container with amended soil is great to do at that point. Or you could add some food on top if you're in your final container.

Having a balanced soil mix is important. What are you putting in it? Yellow spotting or yellowing around the edges like some of your leaves have are something to pay attention to.

 

[Limolax]

Hey Limolax! The difference with MH vs HPS is how the plants grow. They'll tend to be bushier and tighter with MH and will stretch more with HPS. Plenty of people use just MH so no problem there.

You can definitely add soil to the top. I do that if they are drying out faster than I'd like them to, or when I top dress I'll sometimes also add soil on top with it.

Yellowing/fading leaves on the bottom mean your plant is hungry. Transplanting into a larger container with amended soil is great to do at that point. Or you could add some food on top if you're in your final container.

Having a balanced soil mix is important. What are you putting in it? Yellow spotting or yellowing around the edges like some of your leaves have are something to pay attention to.

Thanks a lot for the quick answer mate. The soil is equal amount of Peatmoss, perlite, potting soil, and vermicompost.

 

[Scrappy-doo]

Did you add any lime or other ph buffer?

Peat is real acidic so mixes add a buffer to bring the ph in the proper range. I use pulverized lime. Very important.

 

[JamieShoes]

just a note to add, the very bottom fans kinda always go yellow and die.. thats normal...or at least, it is in my house... as long as everything else looks fine I don't bother about it.....

using MH bulbs during flowering will (in some peoples opinion) give you a better expression of the cannaboid profile (more natural spectrum they say).. some growers even prefer them....generally ppl run HPS though and most ballast will run either (check the sides or manufacturers website for info) so it's just a case of getting hold of a bulb - they sell HPS bulbs in shops other than growshops as theyre used in all kinds of general application lighting - streets, back yards, boats, stadiums etc

frankly, you're in good hands here, SD gives solid advice

 

[Chunkypigs]

Your plants look fine, no worries about a yellow fan or 2.
I got freaked out by the exact same thing on my 1st grow so I put one of the yellow leaves
in a baggie and took it to the grow store to ask the clerk about it.
Dude freaked when I pulled it out in his shop, lol!

If you use MH all the way through flowering your gear will win the Cup!

That's my secret…
Good luck with your grow!