Every gardener knows that water and air are an essential component of growing vigorous, healthy plants. However, many gardens and soil mixes don’t have the necessary constituents to ensure the healthy growth of plants.
Clay soils experience waterlogging, and sandy soils drain water away from the roots of your plants too quickly. Finding the right balance of moisture retention and drainage is a challenge for many gardeners. It’s especially tricky to get things right when you’re dealing with planting flowers or vegetables that are picky about growing conditions.
If you’re dealing with these issues in your garden, adding vermiculite to your soil is an excellent option. However, while many gardeners may have seen the stuff lying around the garden center, many don’t know how to use it in the garden.
In this brief guide, we’ll give you everything you need to know about using vermiculite in your gardening.
What is Vermiculite?
You can find vermiculite readily available at your local garden center or online retailer. Vermiculite comes by itself or blended into soil mixes. Vermiculite is the ideal substrate for growing seedlings, providing them with the moisture and sir they need to thrive.
Vermiculite describes a class of hydrated laminar minerals, which take on the appearance of mica. The vermiculite we use in the garden undergoes a heat treatment process that expands the material into pellets made of layers of thin plates.
Vermiculite doesn’t deteriorate or rot, its mold-resistant, odorless, sterile, and non-toxic. Vermiculite has an average pH of around 7.0, but it depends on the source of the vermiculite and the environmental conditions around the quarry.
Overall, vermiculite is a lightweight material that’s absorbent and airy, making it the ideal choice for a soil amendment for the garden.
You can add your vermiculite directly to flowerbeds in the garden, or use it as an amendment in potting soils. Adding vermiculite to the spoil mix improves moisture retention and aeration of the soil, allowing for the rapid growth of the plant’s roots.
It’s common for garden centers and nurseries to include the use of perlite in soil mixes. Vermiculite offers the gardeners the same properties, but with better moisture retention. While vermiculite may not provide as much aeration to the roots of the plant, it’s the top-choice soil amendment where moisture retention is a concern.
Other Uses for Vermiculite
Add the vermiculite to your soil for lightening and conditioning in conjunction with compost or peat, or alone. This strategy accelerates the growth and development of the plant’s root systems. Using vermiculite for your plants growing medium also helps the plant with absorbing minerals like potassium, ammonium, magnesium, and calcium from the soil.
Use medium-grade vermiculite as a substrate for growing your cuttings. Water the vermiculite thoroughly, and then insert the node directly into the vermiculite. Using this strategy for cuttings helps them root faster.
When using your vermiculite without any soil, make sure that you feed cuttings and seedlings with a weak dilution of all-purpose plant fertilizer at least once a week, after the first leaves appear on the plant.
Vermiculite is a sterile substrate, meaning that damping-off is not a concern, and you can remove the seedlings from the seeding tray without damaging the roots.
Mix soil and vermiculite in a 50/50 ratio with peat, potting soil, or compost reduces packing down in flower pots and containers for growing indoors. At the same time, it enhances the moisture of the soil while improving aeration to the roots.
Those gardeners wishing to transplant using vermiculite as the substrate of choice must dig a hole 6-inches wider than the plant’s root system. Mix the vermiculite into the excavated earth, and then return it to the hole.
Aerating Your Garden with Vermiculite
Here is a step-by-step guide to using vermiculite in your gardening.
Purchase Your Vermiculite
You can pick up some vermiculite from your local garden center or nursery, and many hardware stores also carry the stuff.
Vermiculite is relatively inexpensive, and readily available, with a 2-pound bag costing around $11. Check out online retailers, but make sure they are offering free delivery with your purchase.
Is Vermiculite the Right Choice for Your Garden?
If you’re planning on planting flowers in containers, then vermiculite is an excellent choice for a soil amendment due to its water-retaining properties. However, it’s important to note that not all soil types benefit from the addition of vermiculite.
If you add vermiculite to clay soils, it may become waterlogged and soggy, reducing the airflow around the roots of the plant. Some soil mixtures feature airy components like coconut peat, might not get any benefit from the addition of vermiculite as a soil amendment.
Vermiculite suits growing hot climates, where gardeners need to water their flowerbeds frequently to ensure the soil is moist. Adding vermiculite to your land in these types of goring conditions ensures that the roots of your plants are always airy and moist.
Preparing the Growing Container
If you’re growing indoor plants in containers, then add some vermiculite to your potting mix. You can use any size container you like with vermiculite, but make sure that you have enough vermiculite to amend the soil to the correct level before planting your indoor flowers.
Using the Vermiculite
Start the planting process by tearing open your bag of vermiculite. We suggest that you use a ratio of around 25% vermiculite to the soil. This ratio is ideal for improving the aeration of the plant and retaining moisture in the soil.
This ration provides your plants with the ideal soil conditions to initiate rapid growth. Rip open the bag of vermiculite and use your hands to scoop it out into the pot. Take a rough estimate of the 25% mark, and then pour in the soil on top of the vermiculite.
Work the soil and the vermiculite together using your hands, ensuring that you get an even distribution of the two materials. Don’t worry about getting the vermiculite on your hands, it’s sterile and non-toxic, even if it looks strange.
Gardeners can also add vermiculite to other soil amendments like perlite or peat moss as well.
Spreading the Vermiculite
Because your container or pot is likely very small, if you’re growing indoors, you’ll need to make the most of the growing environment.
Do this by mixing the soil through the pot with your hands, not a spade. Make sure you add vermiculite to your container before you plant, as adding it after planting may result in damage to the roots.
If you’re growing in a very small container, add both the vermiculite and the soil to a plastic bag, and then shake it up to mix the two. After mixing the two substrates, you can transfer plants to your container, or start sowing your seeds.
For gardeners transferring plants to another container, make sure that you remove all of the old soil from around the roots before replanting. For those gardeners growing from seed, make sure that you add your seeds to the soil at the recommended planting depth as displayed on the seed packet.
When transplanting to a different container, you must minimize any damage to the roots. Breaking the roots slows the plant’s growth, and it has a difficult time trying to manage the fallout from the shock of the transplant.
Dig a small hole in the surface of the soil before planting, and make sure that you cover the roots entirely before watering if necessary. Not all plants require watering after you finish the transplanting process, so check up on its requirements before you complete this step.
Sprinkle some vermiculite around the base of the plant for additional water retention, and to replace the soil you lose in the transplanting process.
Cover Your Small Seeds
Gardeners can cover small seeds with an additional thin layer of vermiculite. This strategy helps the seeds to retain moisture in the growing medium in this critical stage of germination.
Also, the vermiculite will help fend off the growth of weeds, although most gardeners won’t experience this issue when growing plants in containers indoors.
Water the Container
Watering your plants is an essential part of gardening. Without water, your plants start to die. Adding vermiculite to the soil ensures the plant has adequate moisture in the soil at all times, reducing the need to water throughout the growing season.
Gardeners also need to be careful that they don’t overwater. The vermiculite will hold onto the moisture, resulting in the development of root rot in your plants.
Remove Excess Water
After watering the plant for the first time after potting, turn it upside down and let the excess water drain out of the pot or container. If you’re dealing with a larger pot, tip it on its side to let the excess water drain from the soil.
Add to Existing Compost
While vermiculite makes an excellent soil amendment for indoor plants, it also has plenty of benefits to offer your garden as well. Spread vermiculite in your compost, sticking to the 25% ratio. The addition of vermiculite means you can water your garden less often during the summertime.