Diatomaceous Earth + beneficial bugs

Discussion in 'Indoor and Greenhouse Plants' started by May Pantaleon, Sep 16, 2020.

  1. May Pantaleon

    May Pantaleon New Member

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    Hi,

    I've added diatomaceous earth to some of my tropical plants and I'm wondering of purchasing and adding beneficial bugs for extra prevention of spider mites, thrips etc. I heard the DE is bad for all bugs. Is this true?

    Thanks again in advance!
     
  2. Tom Hulse

    Tom Hulse Active Member 10 Years

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    Not sure if that is true for every bug, but it is certainly not the best way to kill spider mites. Everyone has spider mites. Literally everyone. So they are not something you accidentally catch. Rather, they are allowed to flourish into an infestation when the plants are cared for poorly. They cannot thrive when the leaves and stems are regularly washed with plain water, including the undersides of the leaves. Your plant has natural defences against them. Severely mite-damage leaves probably won't ever get those defences back individually, but if you just wash the whole plant every time you water for awhile, then wash again maybe every 6 months after the infestation is gone, you can easily cure it in a few months or less. Start by blasting them off with a sharp spray next time you water.

    The same treatment will work for thrips if you also make sure the plant is getting enough sun to avoid leggy, etiolated growth.
     
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  3. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    Perhaps you are considering deploying predatory mites. If so, I would think diatomaceous earth, if effective against spider mites, would also kill the predatory mites.
     
  4. May Pantaleon

    May Pantaleon New Member

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    Hi Tom,

    Thanks for the reply and the advice. Great to know that plants has natural defences against spider mites. I spray my plants in the tub every now and then, I just really hate bugs and wanted to release predatory mites to prevent all them, if I could? But since I added DE to some of my houseplants' soil, I was wondering if that will kill the good guys as well? Do you think it is necessary for me to release predatory mites if I already take good care of them? Thanks again :)
     
  5. May Pantaleon

    May Pantaleon New Member

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    Yes, that is what I meant. Sorry, I wasn't clear on that. I am hoping DE won't kill them so that I could deploy predatory mites as part of my planned winter care routine. This is actually my first winter with a lot of tropical house plants and I guess I am a little paranoid. haha. Are spider mites, thrips, etc. active in winter? Thanks in advance :)
     
  6. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    It depends on the environment. I expect they would be in a heated greenhouse but not so much otherwise. I grow one group of plants in an unheated, enclosed balcony and another in a room inside. I may have had the odd outbreak inside during the colder months but definitely not in the balcony.
     
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  7. Tom Hulse

    Tom Hulse Active Member 10 Years

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    May, I agree with Junglekeeper that any effects that you hope your diatomaceous earth will have on spider mites will probably also apply to your predatory mites. No, I do not think it is necessary at all to deploy predatory mites to control spider mites. Your good culture habits plus the plants natural defences will do an excellent job instead.

    Regarding your question if spider mites are active in the winter, for me personally yes that is the only time of year I have any risk of them. Because I'm in a winter heating climate and most of my plants are inside the heated envelope of the house, that is when my humidity levels plummet; when the forced-air furnace is on the most. Low humidity can be a major contributor to spider mites, but can be overcome by regular rinsing (including stalks and under leaves) and healthy plants. I have much higher household humidity in the summer and so much lower risk then.

    Another major factor is the overall health of the plant. Have you ever noticed how a healthy plant with the right amount of wide-spectrum fertilizer and the right amount of sun produces very glossy, shiny, healthy-looking leaves; and a stressed plant's leaves are duller? That shiny, healthy leaf has much better defences against spider mites. A high-quality fertilizer, especially when the plant is able to get enough silicon, really contributes to spider mite resistance. These type of silicon additives have been proven to reduce the effect of spider mites. However I personally prefer to get my plant's silicon thru a wide diversity of soil ingredients. The number one solution, by far, is still just washing the leaves.
     
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  8. May Pantaleon

    May Pantaleon New Member

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    Thanks, for your help Junglekeeper. I feel so much better now that you and Tom Hulse gave me such great advice. Thanks again! :)
     
  9. May Pantaleon

    May Pantaleon New Member

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    Thank you! I'm having fun learning all these things that I did not know before! I will look into silicon additives as I've never heard of it before. Would you mind if I ask you what your soil recipe is? I use mostly bark, charcoal, coco coir, worm castings and perlite with a little bit of diatomaceous earth for my aroids. For my calatheas I use the same ingredients but I add a little bit of potting soil. Would you add or take away anything? Sorry, if I'm asking too many questions. Hope you don't mind and thanks again! :D
     
  10. Tom Hulse

    Tom Hulse Active Member 10 Years

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    May, here is a link to my potting soil recipe. Your mix sounds like a great one, depending of course on your balance of ingredients to promote good drainage, not too much charcoal to keep the pH down, and quality of the bark of the bark you use.

    The changes I would make are more esoteric, reaching for a very minor extra advantage, so I don't mean to say there is anything wrong at all with your mix. You can see from my link that I prefer peat-based mixes, especially with quality blonde peat that holds more air. These can be fine-tuned with extra drainage material to match any level drainage that a bark-based mix has, yet, because peat transfers water better throughout the pot and evaporates faster, I can have a mix that holds more water, even when tuned for an equivalent amount of air and of drying time. Another way to look at that same thing is to say that peat allows a longer watering cycle time if you were to match the same amount of air+fungal-resistance+overwatering-resistance. Because of its lower rate of capillary action, bark tends to hold water longer at just the bottom middle of the pot, so it needs to be mixed with a coarser, more-open structure that dries faster (and thereby in a very small way limits the potential growth of plants in it).

    For drainage materials I like perlite to be about maximum 17% of the overall mix to avoid the nuisance of it floating to the top. But I need at least double that amount of drainage material in my base mix (and much higher in some mixes), so the rest is made up with pumice, which is almost as good at drainage but doesn't float up.

    You can see I also like to use wide-spectrum mineral dusts which are low in heavy metals, for many reasons including the pest resistance we talked about. It's ok to ask more questions, I love talking about dirt! (I know I'm a dirt geek, kind of embarrassing)
     
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  11. May Pantaleon

    May Pantaleon New Member

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    Thank you so much! Would I be able to use this mix for all my tropical plants? When I repotted one of my aroids, I noticed that the roots could definitely be better. I just had no idea if it was because of me, or my soil mix, or if it was just the plant itself. I'm definitely inspired to change my soil and see them thrive like never before. I am beyond excited!
     
  12. Tom Hulse

    Tom Hulse Active Member 10 Years

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    It would be great for most tropical houseplants, as a starting point. I use it as a base only for plants able to tolerate the most water and most nutrients in soil. Then I add extra drainage material for plants such as palms, and even more drainage for some epiphytic plants. I do use it for succulents like jade plants, Sansevieria, or Pachypodium, but not for cactus.

    If you really want to reach that next level with your plants, the two biggest things to usually change, IMO, are more light and a better quality, more-frequent fertilizer. We're often restricted by which windows we have available, but if there is any way to add supplemental artificial light in addition to its regular sunlight, it will have the same effect as the difference you see when fertilizing a dull plant that's never been fertilized. For Fertilizing, I use Dyna-Gro's Foliage-Pro 1/4 tsp/gal at every watering for most houseplants; more for Brugmansia, bananas, and big-leaved Alocasia. My feeling is that with these two changes, plus skilled watering, you could make any houseplant look amazing in almost any soil at all.
     
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