How to Use Vermiculite in a Container Garden

Three Parts:Preparing to Aerate Your GardenUsing VermiculiteMinimizing Vermiculite Risk

Vermiculite is a naturally occurring inorganic compound that is used to condition soil in garden beds.[1] When heated, it expands up to thirty times its original size to produce the horticultural grade. Vermiculite makes the soil ‘fluffy’, thereby helping improve air circulation throughout the soil, as well as making sure that water and nutrients are available for the plant better. It is often used to start root cuttings, amend soil, germinate seeds, store bulbs and root crops, and as a mulch. As such, it's a great material to use if you want to fertilize home gardening projects.

Part 1
Preparing to Aerate Your Garden

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    Purchase vermiculite.[2] On your next trip to a home improvement store, ask a sales representative to direct you to the vermiculite stock. It is usually shelved alongside other garden fertilizers. Fortunately, vermiculite is relatively cheap; you'll be able to purchase a 1kg bag for under $10.[3]
    • Medium grade vermiculite is the standard choice for gardening.[4]
    • Because vermiculite isn't a particularly popular material to use with gardening, there's a chance a more general store won't keep it in stock. When in doubt, check a gardening outlet for supplies. Looking up stores online will give you an idea of a store's stock without having to physically visit it.[5]
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    Ensure vermiculite works for you.[6] Vermiculite is a solid choice for gardening in containers because of its high level of water retention. Clay-based soils will become soggy with the addition of vermiculite. Although this isn't necessary for soil that already gets adequate rainfall, vermiculite will help maximize the moisture your container receives if it needs that extra push.
    • Although you should still regularly water a gardening container manually, vermiculite is good if your climate is hot and doesn't get much rain on its own.[7]
    • Peat, perlite and manures are alternatives that may better suit your gardening situation if you're looking for a more general fertilizer.
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    Prepare a container.[8] Growing plants in a container will allow you to better control the growth conditions. Take four 2x6 wooden boards and nail them together to create a four foot square box. This amount of space should be enough to grow the majority of container plants.
    • Saw down the boards first to make sure they're smooth-edged and are the same width and length before you nail them together.
    • Two nails (on near the top and one near the bottom) should be enough to firmly secure one board to another.
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    Make a foundation using newspaper or cardboard.[9] Giving your box a floor will limit the plant's roots from encroaching beyond the container while it's growing. Something simple and biodegradable like cardboard or newspaper is a perfect foundation. From there, you can fill up your container with plant-appropriate soil.
    • Landscape fabric is another alternative for this purpose.

Part 2
Using Vermiculite

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    Pour vermiculite from the bag into soil.[10] 20-25% vermiculite will have a major effect on a soil plot's ability to retain water and promote plant growth. Open up your vermiculite bag and drain the contents into the soil you have prepared for the container. When this is finished, you can add the soil mix to the container.
    • It helps to measure out the soil into your container beforehand. That way, you can add vermiculite until it reaches the 20-25% goal.
    • Add vermiculite with soil or moss peat. Peat is another well-known fertilizer. You can increase the fertilization by combining vermiculite as such. Vermiculite may also be used on its own.
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    Spread the vermiculite evenly. Because a container is relatively small you'll want to make the most of the entire soil area. You can do this by spreading the vermiculite throughout the pot with a spade. You may add vermiculite to the soil before adding it to the container. This way, you can mix it together without worrying about damaging the plants.
    • If you've properly measured out how much soil needs to go into the container, having that amount in a bag and adding the vermiculite to the bag will allow you to shake it up, thereby distributing it without having to proportion it out yourself.
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    Seed, or transfer plants into your container.[11] After you have aerated the soil, add your seeds or plants to the container. If you're transferring a plant, lift it out gently from its original pot and place it in the desired spot in the container. If you're seeding the container from scratch, add seeds and bury them just beneath the soil's surface.
    • The seeds should be buried just beneath the surface. Don't put them too far into the soil or they'll have a hard time germinating.
    • Be careful not to damage the roots of your plant if you transfer them into the container. Dig a small hole for it beforehand, and gently place it in. It may be helpful to place some fresh vermiculite around the plant to account for the dry soil the new plant brought in with it.
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    Cover small seeds.[12] Covering smaller seeds with an added bit of vermiculite will help lend them some much-needed moisture during the early growing stages. In addition, vermiculite helps fend against weeds, although you shouldn't have a problem with them in a closed container environment.
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    Water your container. Watering plants is a vital part of gardening. This is especially true if you're gardening with a container, as you'll need to take that much more control of the growth process. Due to the high level of water retention in vermiculite, you should take care not to overwater your plants. Give your container a shower dispersed evenly throughout the area, but don't allow pools of water to form on the soil's surface.
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    Pour out excess water.[13] Because vermiculite retains water so well, you don't have to have too much water in your container. Turn the container slightly on its side and let out the excess water.
    • Alternatively, you can allow the water to drain out naturally.[14]
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    Improve an existing compost.[15] In addition to a container garden, you can add vermiculite to existing compost in order to further aerate it. Add 20-25% of the compost's volume worth of vermiculite and mix them together thoroughly.

Part 3
Minimizing Vermiculite Risk

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    Acknowledge vermiculite's association with asbestos.[16] Because vermiculite is sometimes associated with asbestos, you should keep asbestos risk in mind whenever handling it. Although the main source of contamination (a mine accident at the Libby Mine in Montana) is no longer being sold, there's still some stigma due to the association.
    • If you are concerned about this, you can have a sample of your vermiculite sent to a lab for testing.[17]
    • Asbestos is a material used to insulate buildings. It is poisonous to humans.
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    Avoid the attic for storage.[18] Asbestos is commonly used in insulation with housing. Because vermiculite picks up asbestos so easily, you shouldn't store it in an attic, or other places where there's a lot of insulation.
    • Putting it in a shed should be fine, so long as the area is free of moisture.
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    Call an expert if there's trouble. In the case where you think asbestos may have tainted your vermiculite, don't hesitate to reach out to a professional. A professional well-versed in insulation and asbestos should help out your situation.[19]
    • If you notice something acting up in the vermiculite or negative signs to your personal health, you should see a doctor immediately.
    • Shortness of breath, coughing and chest pain are all signs of asbestos contamination.[20]


  • Vermiculite is perfect for aerating trapped houseplants.[21]


  • The material perlite is known to work better than vermiculite in hydroponics settings, as well as soils with neutral pH levels.[22]
  • Following a disaster at the Montana mine where a lot of vermiculite has been harvested, there is an asbestos scare associated with this material. Although storebought vermiculite has undergone safety testing, this stigma is still worthy to consider.[23]

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