Fafard Potting Mix? PH Problems?

Hey all, I am using Fafard Professional Potting Mix in my plants. I planted the seeds on July 14th so they are a month old now.

I have two out of six plants that seem to be doing fine. The other four have yellowing interveinally and are drooping hard. Obvious PH problems. I'm not overwatering.

My water going in is 6.8, coming out 5.5. I've flushed them all with 6.8 and I'm still having this low runoff PH problem.

I've tried foliar feeding a few to see if I can correct the lockout I'm getting but they aren't looking all that much better.

Should I pot up to a 3 gallon and mix some new soil? If so, what kind?

ledtime,
I use the Fafhard 'red bag' mix when I can get it, MG soil otherwise. The soil likes to go acidic. I'm still battling a mid-flower (after about 4 weeks of 12/12) yellowing issue with pH adjustment and flushing. Trying to dial things in.

The stuff I buy when the garden center has it (no continuous release fertilizer) - Potting Soil : : Fafard

Now the stuff I use is probably not the "professional" mix you use. What I've done to mitigate the soil going weird is to mix 1 to 2 tablespoons of fine lime in with the soil and perlite before potting. Then I watch runoff pH and top-dress with lime as needed. If you use the 'professional' stuff (I need to find a source of it) you may find this email I received from fafhard regarding the pH of their products:

<quote>
Fafard professional potting mix (no CRF) should have a pH outcome of 5.8 to 6.2 with a once weekly application of liquid fertilizer for up to 10 weeks. Liquid organic fertilizers tend to contain a high degree of ammonium and urea which drive the pH down. Apply clear water in between fertilizer applications.



Top dress with a quarter teaspoon of Osmocote for 4 inch pots and a half teaspoon for 6 inch pots if organic fertilizers are not used. Dolomitic limestone can be topdressed at 8 to 10 weeks at a teaspoon per pot (water in well). Limestone prevents low pH and keeps calcium in the system to prevent blossom end rot.




In summary even organic fertilizers cause concern of plant quality for homeowners.
</quote>

Hope this helps!