Spider mites

Bill284

Member of the Month: March 2021; April 2022 - Grow Journal of the Month: April 2021 - Plant of the Month: Nov 2021 - Member of the Year: 2021
I’m a newbie and just learning about spider mites. My question is : Is there a way to treat the soil before plating to kill those little monsters?
Good morning @Stoned grannymama hope you are well today.
Soli growers cook or disinfected soil to kill bugs eggs and larve prior to planting.

Stay safe
Bill
 

SmokingWings

Well-Known Member
Welcome to the group.

Yes, the soil can be sterilized as @Bill284 mentions. Remember that Mites are tiny and light weight. They can get into an indoor grow just by floating on the air when the doors are opened and closed. They can get in by being on our clothes and blowing off when we are near a fan in the grow area.

I treat the plants for any Mites on the leaves. I feel that the number of Mites that might be in the soil is not the real problem. It is their ability to lay eggs all over the underside of the leaves that causes the trouble.

Mites are relentless. Find a product that will kill the adults off and follow any spray schedule listed on the package. Do not let up because it looks like the problem is ending. Follow through.

Once you have solved the Mite problem it is time to continue treating for them. There are 'maintenance' schedules that could, and should, be followed otherwise they will return and seek revenge.
 

Bill284

Member of the Month: March 2021; April 2022 - Grow Journal of the Month: April 2021 - Plant of the Month: Nov 2021 - Member of the Year: 2021

SmokingWings

Well-Known Member
in the oven? At what temp and for how long?
You will have to do a google style search using the question of "how to sterilize soil in the oven". Usually the temperature is about 150 degrees F. But, some people like higher temperatures all the way up to 250.

I do not think that putting the soil in the oven to kill off mites is necessary. From what I have read the only time that Mites go into the soil is in the fall. They will burrow into the top couple of inches and hibernate. When the soil is brought inside and warms up they will come up to the surface and look for plants to live on.

Sterilizing the soil is used to kill of many molds, fungus and mildews or their spores. Also other insects and eggs do not tolerate even the 150 degree heat.

One point that is not always mentioned but the soil can give off an odor while in the hot oven. From experience I know that I do not care for the smell and my wife does not even notice. Not a big deal but mentioning just to let you know.
 

Phytoplankton

Well-Known Member
An alternative to the oven, and this only works in the summer, is to spread the soil a couple inches deep on a tarp and cover it with 4ml. black plastic in the direct sunlight, tack down the edges with wood or stones to hold the heat in. The sun will cook the soil to well over 150 degrees. I have used this method to kill entire patches of bamboo (arundo), and that is some tough stuff!

You've got the right idea, prevention is much easier than curing the problem! Don't know if you're growing indoors or outdoors, but in either case you can spray the soil and surrounding areas (and nearby non marijuana plants) with pyrethrin to kill any live spider mites (or other insects), might want to do it a couple times about 3 days apart. The same can be done inside the tent BEFORE you plant. I like pyrethrin because it's a plant based poison found in Chrysanthemums, it degrades within a couple days when exposed to light, and it's a non-systemic (meaning it's not absorbed into the plant). I would NEVER spray with pyrethrin once flowering starts.
 
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SmokingWings

Well-Known Member
I have used this method to kill entire patches of bamboo (arundo)!
Looked it up. It is usually called a type of cane or swamp grass. It is getting out of control in wetlands and drainage ditches that are connected to Lake St. Clair, the St Clair Rvr and Detroit Rvr. When you said 'bamboo' I thought you were talking about Japanese Knotweed. Now I am wondering if it will get hot enough to kill that stuff.
 

nivek

Photo of the Month: Oct 2018
You will need a large oven-proof container, your soil, aluminum foil, an oven-safe thermometer, and water.


  1. Preheat your oven to 200 degrees Fahrenheit.
  2. Fill your container to about three inches deep with soil. Don’t make it too deep or the middle layer of soil will not get hot enough. Remove any rocks or leftover plant matter.
  3. Wet the soil just enough to moisten it completely. The water will create steam that will kill contaminants in the soil, however, too much water will slow down or stop the process.
  4. Cover your container with aluminum foil to prevent the soil drying out ahead of the sterilization process occurring.
  5. Measure the temperature of the soil with a heat-safe thermometer. Once the soil temperature reaches 180 degrees Fahrenheit, bake the soil for thirty minutes, keeping the oven door closed the entire time.
  6. Turn off the oven.
  7. All the soil to cool down until it reaches room temperature. Once the soil is cool, it is ready to use.
  8. Serve with lashing of cream…joke!
 

420giirl

Well-Known Member
I had the same problem my first grow with lil gnats flying all around, so annoying. I did read somewhere about the oven method for drying soil but I couldn’t imagine putting dirt in my oven lol so instead I bought a plastic tote with a lid and poked a bunch of holes on top and keep it in my garage where it gets really hot in the summer. Worked like a charm, now I just make sure to keep it filled with dry/baked soil. Ready for the winter months, ready for my next grow.
Not to mention how the tote is a perfect way to store soil, period.
:snowboating:
Ps. Please excuse my garage floor.

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I just make sure to give it a mix with the little shovel every now and again.
 

SmokingWings

Well-Known Member
I couldn’t imagine putting dirt in my oven
Understandable. But, we will go and put a 5 lb chunk of bloody meat in the oven. Oh, the garage floor looks fine. It looks cleaner than some of the floors in a person's kitchen or dining room judging by some of the photograph I have seen.;)

I did read somewhere about the oven method for drying soil
There is a difference between drying the soil and sterilizing it. Drying will kill off many insects and their larvae but eggs and weed seeds can last years in dry soil and then hatch or sprout when the soil gets moist once again.

Sterilizing is a way to heat it to 150F, or up to 200 degrees F, as a way to kill off most of the seeds, eggs and many of the soil micro-organisms that can attack a plant.
 

Phytoplankton

Well-Known Member
Understandable. But, we will go and put a 5 lb chunk of bloody meat in the oven. Oh, the garage floor looks fine. It looks cleaner than some of the floors in a person's kitchen or dining room judging by some of the photograph I have seen.;)


There is a difference between drying the soil and sterilizing it. Drying will kill off many insects and their larvae but eggs and weed seeds can last years in dry soil and then hatch or sprout when the soil gets moist once again.

Sterilizing is a way to heat it to 150F, or up to 200 degrees F, as a way to kill off most of the seeds, eggs and many of the soil micro-organisms that can attack a plant.

Just know that you'll also be killing off the beneficial microrganisms too, so you might want to innoculate the soil before using it.
 

SmokingWings

Well-Known Member
Just know that you'll also be killing off the beneficial microrganisms too, so you might want to innoculate the soil before using it.
That was one of my concerns the first time I tried sterilizing soil. I remember that the topic of sterilizing soil came up in a thread here a couple of years ago. It was brought up that the soil starts to recover within days without having to do anything.

Don't know how it works but I figure that the heat does not kill everything and does not ruin the organic materials in the soil. Plus I believe that many of these micro-organisms are just floating around in the air, stuck to our skin and clothes and eventually come down somewhere and start living there if conditions are right.
 
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