Stinky soil in office plant

Discussion in 'HortForum' started by CAGgarden, Jun 7, 2010.

  1. CAGgarden

    CAGgarden Member

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    Hi. The soil from one of our office plants suddenly started to smell like rotten eggs- very sulpheric. Is this normal? I've attached a photo of the plant just in case it helps. Thanks so much in advance for any replies!
     

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  2. saltcedar

    saltcedar Rising Contributor 10 Years

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    Anaerobic bacteria release Hydrogen sulfide.
    I suspect overwatering.
     
  3. photopro

    photopro Well-Known Member

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    Sounds absolutely correct. The proper potting of the specimen is important if you want to cure your problem.

    The common advice on most garden websites is to allow a plant to dry well between watering. In reality, the entirety of the soil needs to remain evenly damp so the roots of the plant can continue to draw in fresh oxygen. Otherwise, root rot is likely to begin as a result of fermentation the soil. Since most people don't want to bother with ever watering their plants, many people just go into a garden store and a very rich potting soil that stays soggy all the time. Despite the belief that are giving the plant "rich" soil to make it thrive they may be dooming their specimen to death.

    Anyone that has asthma knows the difficulty of getting air out and then drawing it back in. Even though plants release oxygen into the air through their leaves they draw fresh oxygen into the plant through their roots. A potted plant is much like your lungs and if you can't bring in fresh oxygen you will soon cease to live. As a result the top layer of a potted plant's soil should not be allowed to dry since that dry soil prevents the intake of fresh air. Once the soil dries it creates a "blanket effect" to hold in the stale moisture and keep out fresh oxygen. Once the soil dries the moist layer below cannot easily breathe in order to re-oxygenate the soil that soon becomes anoxic. Anoxia causes root rot, The dry upper layer actually prevents the capillary effect of the wet surface evaporation when damp soil is exposed to air. When you pour water in the air inside the soil is displaced so the oxygenated air inside has left the pot. If the upper soil layer completely dries the "lungs" of the pot cannot work and can no longer continue to draw in another breath of fresh air.

    Despite the belief of far too many growers, growing tropical plants is not just about the water content of the soil but the use of a well mixed soil and keeping it evenly damp. The advice to water only once a week and keep the top two inches of the soil dry is not always good advice! Instead, proper growth is about the fast flow of water through the soil or the lack thereof that causes a lack of oxygen, anaerobic fermentation and saprophytes that are encouraged to live that soon turn into pathogens. Saprophytes are organisms including fungus or bacteria that grow on and draw nourishment from dead or decaying organic matter that often includes soggy wet soil. The pathogens attack the roots and cause them to rot so all of the advice to "slow down on the water" is really about how to control the pathogens.

    Fermentation and saprophytes often occur in muddy soil that will not allow the roots to breathe but they don't necessarily occur in water which is why we can cause a plant that is about to die to grow new roots only in clean water. As a result, it is necessary to use soil mixes that allow the roots to breathe and will not remain soggy. I've frequently tried to explain the necessity of mixing proper soil for plants but the advice is often ignored since it requires some "work" on the part of the plant's keeper. The reason plants rot and the soil smells bad is not the amount of water given to the plant! These are often rain forest plants and are literally drowned for months at a time! Instead, it is about keeping the root system out of mud that is in capable of drawing in fresh oxygen.

    If you could visit a rain forest you would quickly learn the soil is composed of leaf litter, decaying wood, compost, animal droppings and the charcoal left behind when a part of the forest burns. That is precisely what I attempt to explain when I recommend mixing soil, not just buying a bag at the store. Over time we've arrived at a soil mixture for most of our tropical plants which duplicates the rain forest. We use this mixture on the advice of the greenhouse keepers at the Missouri Botanical Garden in St. Louis. The goal of this mix is to allow the roots to freely find moisture along with places to extend and grow without constantly finding soggy wet places where they will rot. This mix will remain damp but drain quickly and as you can see from the photo above will make the plants thrive.

    Rather than using a rich, soggy soil and watering only once a week (or less), use a soil that holds moisture well but drains quickly. The exact mixture is not critical but we use roughly 40% potting mix combined with 30% high quality peat moss, 20% orchid potting media containing charcoal, hard wood and gravel), and the balance cypress mulch mixed with Perliteā„¢ and finely shredded pieces of sphagnum moss. We often add extra hardwood charcoal to help purify the soil and sometimes volcanic rock If you are concerned about your soil remaining wet just add more orchid mix, cypress mulch, Perlite and sphagnum moss.

    The cure for your plant will require that it be removed from its current soil and the soil discarded. Any rotting roots removed, and then the plant repotted in a very good soil mixture that is kept evenly damp. Be certain the pot can freely drain. Most tropical plants prefer bright light, not the darkness of a corner. The lucky thing about your plant is it is a species from Africa that can live with less moisture so some drying is OK, just don't over water and avoid under watering. Stick your finger in the soil and if you don't feel some dampness it is too dry. If it is soggy, stop watering until the soil returns to an even consistency.
     

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  4. CAGgarden

    CAGgarden Member

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    Thanks you guys! You're absolutely correct. I water the plants once a week but this one plant happens to be near the cubicles and another person was taking it upon themselves to water it every other day. :( mystery solved! This site is the best!
     

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