Potting soil for Gallon pots and larger

Discussion in 'Soils, Fertilizers and Composting' started by Dave Finch, Nov 15, 2007.

  1. Dave Finch

    Dave Finch Member

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    I was recently told that while potting soil for small pots up to 3" it is okay to use a soil-less mix, but for larger pots in which the plant is expected to develop a strong root system the mix should contain more nutrients and mychhorizae (Sp?). This makes sense to me, but I am not sure what the ideal proportions of earth to other ingredients such as vermiculite, perlite, sand, etc. etc. I would appreciate some help with a soil recipe for potting up seedlings and such?
     
  2. terrestrial_man

    terrestrial_man Active Member 10 Years

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    I believe that most commercial mixes are a combination of decomposed bark/wood products, peat moss, and perlite. For feeding the plants use a balanced liquid food.
    Check out the formulas on the mixes. I like the 12-8-4 formula of MiracleGro Liquid Plant food as it is perfect for orchids and can be used with every watering during their growing seasons. As it is a foliar food you do not have to soak down the soil mix to get the desired result.
    I think it would be best to keep your mix restricted to a few basic ingredients as above and feed rather than try to incorporate nutrients into your mix. You have much more control over plant growth with the former and established method than the latter which depends upon a number of variables that may defeat your formulated mix.
    For a simple addition I would use osmocote slow release but again I recommend using a liquid foliar feed as well.
    Here is a link to a modified UC Mix. It is designed for mixing by large commercial growers and so you would need to factor down the amount of each of the ingredients shown.
    http://tgrc.ucdavis.edu/soils.html
     
  3. SUNRIZE

    SUNRIZE Active Member

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    Hi Dave,

    With my own experimenting I’ve decide that using a commercial potting soil is ok. I would recommend not going with the most expensive because usually it’s heavy and sticky and doesn’t drain well also don’t get the .99 cents a bag its mostly just sand. I buy the mid grade. My first choice is Scotts followed by Wal-Mart all experts Brand. Unless you’re growing something like Orchids or Bonsai that need special soil I wouldn’t complicate things to much. Keep in mind the kind of pot your using (clay versus plastic). Type of plant, (does it want to be moister or does it need to be on the dry side). Is the plant currently growing or is it dormant. Is the plant in the sun or in the shade? If it’s a plant that likes more moisture I usually add more moisture retentive additives and plant it in plastic. Other wise I prefer clay. Since clay dries out faster then plastic. Bottom line just make sure what ever you choose it drains well.
     
  4. Dave Finch

    Dave Finch Member

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    All helpful information. The lingering question I have is whether in the early development of plants that will stay in pots for a substantial period, such as those potted in 1 gal to 5 gal pots, is it necessary to provide mycorrhizae by adding in some natural soil. I was told that for good root development the fungus helps the roots take up nutrients. I have always read that plants in the ground depend on this soil feature, but I don't know whether soil-less mixes supply it, or whether it would be advisable to add some dirt.
     
  5. 1950Greg

    1950Greg Active Member

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    You don't need fungus in your potting soil ,in fact for starting plants it might be better to have sterilized soil. If you use liquid fertilizer it is already in a formula accessable to the plant. What bacteria,fungus,protozoa and all the other creatures in the natural soil do is make nutrients available to the plant by breaking them down into small enough particals to be use. When I take cuttings I use sterilized soil to inhibit bacterial infections to the cuttings and take care to use a clean enviroment. The mixture I use is 50/50 soil and perilite and root stim fertilizer.
     
  6. Dave Finch

    Dave Finch Member

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    Thanks, 1950Greg, for taking time with a beginner. How great it is to have this resource for learning.
     
  7. Ron B

    Ron B Paragon of Plants 10 Years

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    Mixes used vary with kinds of plants being grown. One grower here has basically two mixes for everything, both based on bark and sand only. The more drainage-sensitive, dry climate plants get a higher proportion of sand. Fertilizer consists of Osmocote and another dry product used in conjunction, although I think what he tries varies - he may be doing something a little different since the last time I saw what the approach was.

    Technically, the mineral content of the irrigation water would be factored in, as this will affect the action of the fertilizer. In California you might have a pretty high mineral presence in the water being used.

    Comparatively recently some stock shipped up from California has been coming with sandy soil in the mix, this trend is probably what you encountered. It isn't necessarily the case that you HAVE to do likewise with your plants to be successful, just that an idea that there is a benefit to doing so has arisen and is being implemented there.
     
    Last edited: Nov 19, 2007
  8. Dave Finch

    Dave Finch Member

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    And it may be an economy measure more than a nutrition enhancement. I'll continue to watch for developments. Thanks for your info.
     
  9. Ron B

    Ron B Paragon of Plants 10 Years

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    "A critical component of the growing process is the soil. Plants grown in nutrient-rich soils are healthier, with stronger root systems. Monrovia is the only grower of premium ornamentals in the world that custom blends 42 different soil mixes, including compost and native soils.

    Seven different types of mycorrhizae are added to our soil mix to create an environment that dramatically increases the life of our plants. Mycorrhizae is a beneficial fungus that develops in and around a plant’s roots, stimulating its nutrient and water uptake, increasing fruit and flower yield, and reducing transplant shock and other environmental stresses."

    http://www.monrovia.com/MonroviaWeb...718f1b62bc4d3809882571b50070b40e!OpenDocument

    (Note that mycorrhiza(e) (fungus + root) is the phenomenon and not the fungus; fungi involved in this are called mychorrhizal fungi)
     

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