First time soiless media grow

Hey all, havent been on RIU in a while. Have had alot of successful soil and outdoor grows....never tried soiless so i decided to take a crack at it...having a common problems in 3 different strains...heres the specs
HPS grow my MH bulb went out so im using hps throughout the entire grow
My plants are about 4-5 weeks from seed
Afgan, og kush and buzz light gear.
20/4 light schedule good temps 75*
Going to start their first feeding this week.
The soiless media is promix #1 ran out of ph down before the grow and i have been using lemon to lower ph of my tap water which comes in as 7.3ish but the lemon gets it down to around 6.2...the probem is all the older growth are browning/oranging/yellowing and a few plants even are stunted....is it just my ph or am i missing something?

Lemon juice doesnt make a good ph down in my experience,ph rises to fast. In soil it works ok because you have more buffering.If your water has alot of carbonates lemon juice seems to cause issues in soiless...I would get some phosphoric or hydrochloric acid for ph down instead.

Resinhound said:

Lemon juice doesnt make a good ph down in my experience,ph rises to fast. In soil it works ok because you have more buffering.If your water has alot of carbonates lemon juice seems to cause issues in soiless...I would get some phosphoric or hydrochloric acid for ph down instead.

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Yeah i figured it was the ph...where could i buy those types of acid from other than online?

Hiramklarke said:

Yeah i figured it was the ph...where could i buy those types of acid from other than online?

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Go to Home Depot or any swimming pool supply. Buy a small unit of muriatic acid. Muriatic acid is hydrochloric acid. No idea why the 2 names but it is commonly sold everywhere as muriatic acid.Used for clean-up on concrete jobs and masonry.

Nice....so i take it that my problem is ph huh?

Hiramklarke said:

Nice....so i take it that my problem is ph huh?

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Its a good place to start.Sounds like you have some experience,im assuming your nutrients are right,they just arent availiable do to excessive ph swing.

Hiramklarke said:

Nice....so i take it that my problem is ph huh?

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They look hungry to me. Pro-Mix doesn't have much food, maybe for a week. (I've never heard of Pro-Mix #1. Are you referring to Sunshine Mix?). If they're 4-5 weeks old without feeding, that's a long time for Pro-Mix.

What are you going to feed? I used GH Flora 3part in soilless with the so-called "Useless feeding schedule." It worked well.

It looks like you should have started fertilizing sooner is all -- she's hungry. Also, being new to soilless, I wouldn't recommend starting in such a large pot. It's much easier to adjust fertilizer strength with plant stage if you go from a one to a three to a five etc. That plant could easily still be in a one gallon.

you should have been feeding every time from sprout, just in proper amounts and volume. what nutrient line are you using? Why is your media so dry?

Resinhound said:

Its a good place to start.Sounds like you have some experience,im assuming your nutrients are right,they just arent availiable do to excessive ph swing.

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Yeah im just not familair with soiless...got a bale for free and had a handful of quality seeds so i figure why not....never had ph issues so i was unsure what to look for

unwine99 said:

It looks like you should have started fertilizing sooner is all -- she's hungry. Also, being new to soilless, I wouldn't recommend starting in such a large pot. It's much easier to adjust fertilizer strength with plant stage if you go from a one to a three to a five etc. That plant could easily still be in a one gallon.

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I actually only have 2 potted in a 5 gal container...the rest are in solo cups..i was experimenting to see if the 5gal would work for me

SamsonsRiddle said:

you should have been feeding every time from sprout, just in proper amounts and volume. what nutrient line are you using? Why is your media so dry?

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I found some nutes at a local fert store...they have a npk ratio of 4.1.0 i forget the brand but they worked fine outdoors and in soil...should i try something different? Btw i have earthworm casting in my media..dont have nutes for flowering yet...also since i was having ph problems i was giving each plant about a cup of water every 2-3 days to keep from over saturating media with inbalanced water

Hiramklarke said:

Btw i have earthworm casting in my media..

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Literally, I don't think that's soilless anymore. You may need to ph your feed to 6.5 like soil. I'm confused about this because I don't understand at what point it becomes a "light soil" versus organically inactive soilless.

I add 20% Kellogg Patio Plus (and 20% perlite) to my Pro-Mix HP and treat it like soil (even though it has only 20% soil).

(Anyway, your use of worm castings in the peat explains how you made it all these weeks without feeding.).

Well i wasnt concerned with what i wanted to call my media...i was under the impression the earthworm castings would just enhance my nitrogen...im super new to soiless...

Hiramklarke said:

Well i wasnt concerned with what i wanted to call my media...

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It may make a difference in your ph. Instead of 5.9 you may need to do 6.5. I don't know how much soil makes soilless more like soil.

Usually soilless is organically inactive and you treat it more like hydro (with hydro nutrients, not nutrients for organically active soil.). That doesn't mean you can't do something else.

I add 20% soil and feed nutrients with organic components (kelp, blood meal, fish emulsion, fulvics). It works well. I don't even ph the nutrients.

Also 6.5

az2000 said:

It may make a difference in your ph. Instead of 5.9 you may need to do 6.5. I don't know how much soil makes soilless more like soil.

Usually soilless is organically inactive and you treat it more like hydro (with hydro nutrients, not nutrients for organically active soil.). That doesn't mean you can't do something else.

I add 20% soil and feed nutrients with organic components (kelp, blood meal, fish emulsion, fulvics). It works well. I don't even ph the nutrients.

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Defintely gonna mix some soil in the 5 gal for my girls that i have in solo cups

Hiramklarke said:

Defintely gonna mix some soil in the 5 gal for my girls that i have in solo cups

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I like soil better, but a very light soil as I described. When I switched to more organic nutrients I (and others) noticed a very distinct taste difference compared to soilless and GH 3part.

What I do is in my sig. But, it's just 60% Pro-Mix HP, 20% Kellogg Patio Plus (potting mix), 20% perlite. It dries in 2-3 days when the plant has grown into it.

5 gal containers sound large. I go party cup to 1gal, then 3gal. They grow 4' tall (from soil). Are you going to scrog or grow really tall?

az2000 said:

I like soil better, but a very light soil as I described. When I switched to more organic nutrients I (and others) noticed a very distinct taste difference compared to soilless and GH 3part.

What I do is in my sig. But, it's just 60% Pro-Mix HP, 20% Kellogg Patio Plus (potting mix), 20% perlite. It dries in 2-3 days when the plant has grown into it.

5 gal containers sound large. I go party cup to 1gal, then 3gal. They grow 4' tall (from soil). Are you going to scrog or grow really tall?

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Ive found alot of success LST my babies

Hiramklarke said:

Also 6.5

Defintely gonna mix some soil in the 5 gal for my girls that i have in solo cups

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I transplanted my solo cup plants that were growing in organic seed starter mix into pro-mix Bx (with vermiculite and perlite) and feed at 5.8 every time. I hate soil, personally. Also, soilless plants like to go from wet to damp, never dry.

With an npk ratio like that you are going to need something else for k. maybe try a silicon supplement that is somewhere in the 0-0-3 npk range (dynagro protekt comes to mind).

If you do stay in soilless, I would also recommend floralicious plus to enhance the flavor. You can buy little containers of it on ebay (as cheap as $5 for 30 gallons worth).

If you are really into this hobby i highly suggest buying things meant for growing plants until you are ready to take the jump into trying new things. Like General Hydroponics ph down works good and is cheap.