70% coco coir + 30% miracle grow potting mix. Need help with pH and feeding schedule.

Hello everyone,

I'm on my second grow. My previous grow was in 100% coco coir (Mo'Koko Premium Select, Imperial Dutch Recipe) and I went organic with the nutes: MediOne in veg and Iguana Juice Bloom in flower (both as per manufacturer's instructions) + supplemental CalMag. I was very happy with the results.

For this grow, I made a mixture of 90% coco and 10% perlite but ran out when all of my 3 gal pots were 70% full. I had already prepped my 2 week olds for transplant so I decided to top-up all of the pots with Miracle Grow potting mix (0.14-0.14-0.14), which is what I had on hand. So, the final mix is approximately 70% coco/perlite and 30% MG. The MG potting mix is literally on top of the coco/perlite mix.

My only experience is with pure coco where my pH was always adjusted to 5.8 and I was able to go a little heavy with the nutes.

My questions: can I still pH to 5.8 or will this change because of the MG? Should I hold off on feeding them MediOne until the MG nutes are used up?

This was 3 days ago and I've only given water pH 5.8. Am I over-thinking this?

Any advice would be much appreciated. I am growing to treat my Crohn's disease so I can't really afford to mess things up. Everything I know, I've learned exclusively from everyone at Rollitup.org. This is the first time I've spoken-up.

Your pH should be 5.8 if ur doing hydro. i am not sure about the potting mix, since this has never happened to me before. but if the miracle grow is a 14-14-14 general purpose fertilizer, then i would not feed them till the next time you feed

Thanks for the quick reply urgod. Have I been using the wrong pH target for my coco? I thought 5.8 was for both soilless and hydro. How many feedings do you think I should skip? I believe the MG potting mix has controlled release nutes in it.

6.5 for soil, 5.8 for hydro. normally, if ur doing soil, you feed on every 3rd watering. so you fed this time, wait till 3 waterings to feed again

grewb said:

Thanks for the quick reply urgod. Have I been using the wrong pH target for my coco? I thought 5.8 was for both soilless and hydro. How many feedings do you think I should skip? I believe the MG potting mix has controlled release nutes in it.

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5.8 is for both soilless and hydro - soilless is intended to be PH inert (but MG isn't PH inert) so you're doing a balancing act between soilless and soil! It may very well still work.. but.. we love to link this little fucker right here:



Notice how the optimal soil PH doesn't sync up with the optimal hydro PH. You might be able to land in between these two to some degree of effectiveness, but as your roots progress they'll end up in the soilless medium (on the bottom) and expect different PH levels (which will be augmented by the water flow through the topsoil).

tl;dr: If you decide to go with it, maybe water with soil PH for veg, flush, then water soilless for flower?

disclaimer: 90% speculation, only hydro experience, very new to soilless (just regurgitating some of what I've read).

Highocaine: watering with soil pH for veg, flushing, and then watering with soilless pH for flower sounds like a good idea to me. Maybe I'll combine that with urgod's suggestion to feed every third watering.

mixing in mg potting mix is a mistake you've gone from a soiless medium to one that contains nutrient and may lead you open to chemical reactions with hydro nutes not to mention to differing buffers

i would stick to 6.0 for the time being as a bit of a compromise on both methods

Agito: well, it definitely complicates things. I wouldn't have done it had I had a way of getting more coco for this grow. Do you think MG nutes would interact with organics? I'm hoping a lot of the MG nutes will be depleted by the time I start hitting it with full-strength organics.

well you should be ok with organics IMO i dont believe organics are best suited to inert media and a higher ph should be used 6.2 should be ok

you may even get better results with 70% compost (organic) 30% coir than going all out coir grow

chemical nutes and soiless mixes are great but in organics you need to give an environment the micro life prefer this reflects my experience

grewb said:

Thanks for the quick reply urgod. Have I been using the wrong pH target for my coco? I thought 5.8 was for both soilless and hydro. How many feedings do you think I should skip? I believe the MG potting mix has controlled release nutes in it.

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Go here and ask Moebius any question regarding soilless. He'll answer all.

https://www.rollitup.org/hydroponics-aeroponics/546006-world-hempy.html

hotrodharley said:

Go here and ask Moebius any question regarding soilless. He'll answer all.

https://www.rollitup.org/hydroponics-aeroponics/546006-world-hempy.html

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Awesome thread! Thanks.