50% promix 30% perlite 20% vermiculite

Discussion in 'Growing Organic Marijuana' started by medicaliOG, May 9, 2011.

  1. What do you guys think? I've been growing hydro for years now and am going to switch to soil.

    I was under the impression soil was easier after being a hydro guy but I have read so many different soil recipes and mixes and It really has taken a lot more thinking than putting water in a reservoir like hydro.

    I am kinda skeptical about putting guano's, kelps and such into my soil mix because i don't like the idea of not knowing how much my plants are feeding? whats do u guys think of that?

    If I go With the above 50-30-20 soil mix about I was planning on using hydropinc based nutrients. Will This soil be feeding my plants at all by it self? How often do you feed in soil(in hydro i was feeding 4 times a day!)? And do you give straight water in between feedings?

    thanks MedicaliOG
  2. Im also wondering about this. If there is one topic that I still have questions on after months of research, its soil.
  3. medicaliOG

    The products from Pro-Mix and Sunshine are designed to be used exactly as you're intending, i.e. chemical fertilizers applied throughout the growing process.

    It's basically 60-65% peat (in some form) and the rest is aeration amendments, i.e perlite, pumice or vermiculite or some combination of these.


  4. #4 Jellyman, May 9, 2011
    Last edited by a moderator: May 9, 2011
    Vermiculite isn't a good substrate, except in some seed-starter mixes.

    Many experienced and even famous growers add no fertilizers to their soil mixes, controlling nutrient levels manually throughout the growing process. Not having any other source of nutrients, the grower needs to provide more precise amounts of each to get the most out of the plants. Having ferts in the soil can be less work and supplying them all manually can be more exact. There is also an argument for ferts mixed into the soil helping microbial life more than applying them all manually.

    As for not knowing what nutrients the plants are getting- If you mix the correct NPK & micronutrient ratios into the soil, you won't get a deficiency in any one nutrient and the only concern too much or too little food in general. Use trial and error adding more ferts to each successive soil mix until you start to burn the plants a little, decrease the ferts a tad and use that recipe from then on.

    You then just need to know when the nutrient levels in the soil decrease. Using manual fertilizations, watching for burn and monitoring plant growth rate, you'll quickly learn when the plants need more and how much more you're able to give them. Always watch the lowest & oldest leaves for signs of fertilizer burn. It starts at the tips of old, low leaves like the pod leaves and the first single-bladed leaves.

    Once you know how strong of a fertilizer solution your plants can handle, you give them all they can take without burn and every other watering just give them plain H2O. If you aren't giving them a full meal at each feeding, plain water every other time may not be enough food and should probably be reduced to every third time.

  5. Thanks jellyfish thats what i was looking for! So scratch the vermiculite, what is a good promix, perlite mixture? I would like to just use my hydronic nutes and control it manually(like above). so you think promix will be good for that? So your saying you feed every time you water once you start feeding nutes? what do u ph ur water at? I've seen 5.9-6.8 seems like a pretty big range(5.6-6.0 hydro)? Just curious if you have found what works best.

    Thanks MedicaliOG
  6. It's been a long time since I've made a substrate mix with Pro-mix and don't currently have a recipe for it. Most of my mixes are eyeballed, adding things like perlite until the soil has the right consistency, rather than by measurement. I start with organic potting soil (Edna's Best) and add about 1/3 its volume in coco coir. I then add about 20-25% of that volume in extra Worm Castings. Next, fertilizers are added like Bone Meal, Blood Meal and Guano. Starting with a big bag of soil, three cups of each organic fertilizer is added. Roughly 15-20% of that volume in Perlite is then added. If this is a new soil mix, a sample of it is taken at this point and pH tested. Finally, the whole mix is watered until a handful of soil drips a few drops when moderately squeezed, with the water's pH set to correct the soil's, if necessary.

    Don't feed every time you water. When giving the plants about the strongest feedings they can handle, you alternate with pure water every other time. If not giving full doses of fertilizer, alternate with plain water every two feedings.

    Plants in regular soil need a pH of about 6.5. Plants growing in soilless mediums need a pH of about 6. Clones usually root best in about 5.8. Sprouting seeds can use plain, pH 7 water. Keep in mind that the pH of your soil and that of your liquids are two different values. If the soil pH is off, it'll change the pH of the liquids you water with. To test soil pH, there are pH meters and other types of testers. Or, you can let water sit in the soil for at least an hour and then squeeze some out & test its pH. After sitting in the soil long enough, plain water will take on the soil's pH and when you test it, it will tell you what pH your soil is.
  7. thanks jellyman

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