The most important factor that is responsible for the success of an indoor plant is choosing the right soil.
The right potting soil helps in good root growth and firm anchoring of the plant.
An ideal potting soil holds moisture and also has a good drainage property.
It provides enough aeration for the roots to consume oxygen and be able to breathe.
The potting medium contains nutrients for the plant. It also has helpful microbes that help increase the number of nutrients as well as uptake of nutrients by the plant.
Choosing the Best Soil for Indoor Plants
The soil that would work best for your plant would be the one that fulfills its needs.
When it comes to pH, some plants like acidic, some like alkaline while others like a neutral environment. Their specific pH helps them to take up nutrients from the soil.
In the same way, different plants need different concentrations of nitrogen, phosphorus, etc according to their species. The plant should be able to get enough nutrition from the soil to help it grow.
The water uptake of the soil is another important factor to be taken into account. The soil should have the ability to absorb moisture as well as have good drainage.
Species like cacti and succulents want coarse soil that gives them maximum drainage. If they are potted in soil that has a lot of moisture, it can lead to root rot for these plants.
Plants like orchids need to be moist but they also so want a lot of air around their roots. Soil containing peat moss, bark, or perlite is perfect for them.
As the plant remains indoors with no wind, there is no movement of the plant causing the soil to become firm.
A light and airy soil will help to spread the roots and thrive. It will lead to a good gas exchange for the roots to breathe. The soil must also have enough structure for root support.
Types of Potting Soil for Indoor Plants
Potting soils are not equal. Some have very little organic material, some are exclusively for specific plants while some have no soil at all in them.
The last one is called a ‘potting mix’ and not a ‘potting soil’.
Potting soil is a gardening media having dirt in it. The dirt can be mixed with soilless material or it could be just plain soil.
The advantage of using potting soil is that it is cheap, organic, lasts for long, and is full of nutrients.
The disadvantage of using potting soil is that it is thick and heavy allowing low aeration. The soil also has a problem of waterlogging.
Garden soil is a free potting medium at zero cost. It is available everywhere. A little soil from any garden is sufficient to grow your babies indoors.
The best thing about garden soil is that it is an entirely natural medium for your plant. Your plants are familiar with it.
Garden soil is usually added to the commercial potting mix as it has an excellent ability to anchor the plant firmly.
A light soil can cause over drainage for indoor plants, leading to water-soluble nutrients being lost quickly. Garden soil effectively holds moisture water and nutrients for a long duration.
Disadvantages of garden soil include mixed impurities like stones, pebbles, nails, roots, and excess of clay. Moisture in a warm climate can cause fungal growth in the garden soil.
The solution is to add organic matter like compost and sand along with the garden soil. Add fungicide, sieve, and dry the garden soil thoroughly (first by heating and then letting it dry naturally).
The potting mix is a plant growing soil-less medium. It’s made up of all the right materials for good plant growth.
The advantage of the potting mix is that it is fluffy, giving good drainage and aeration to the plant.
It also has excellent water-retention property. The potting mix usually comes with the right amount of nutrients for plant growth.
The disadvantage of potting mix that it is a bit costly.
It is lightweight and can fly in windy areas.
The biggest problem is that the potting mix breaks down over time. It is because these mixes are not designed for long term use. Breaking down, it started compressing the plant, drainage is hampered causing an increase in the salt build-up.
The solution is to re-pot the plant every year for the healthy growth of plants. Flush the soil thoroughly every month to remove the excess salt build-up.
Let us now discuss soil building materials that are used to pot indoor plants.
Common Soil builders
Soil builders are natural materials that offer a good structure for anchoring of plant, good water retention and drainage, ample aeration, and right pH according to the plant preference.
The common soil builders are :
Sphagnum offers good water holding capacity, aeration, and has a good structure to support the plant. It is slightly acidic.
Sphagnum decays slowly with time. It is usually mixed with other fertile amendments to compensate for the lack of fertility. Two forms of sphagnum are commonly sold- one is dried sphagnum moss and the other is peat moss.
Dried sphagnum moss is the moss that has been harvested and dried. It has long fibers that are green, brown, or grey.
Peat moss is decayed sphagnum that comes from natural peat bogs. It is a result of a long process of decomposition.
It holds the plant firmly.
Coconut coir is made of coconut husk fibers. Its water absorbing property is greater than peat moss.
Coconut coir as a neutral pH and is lightweight and easy to use. Coir is high in Potassium and can interfere with the calcium absorption of plants.
Coir gives excellent drainage and anchors the plant firmly.
Perlite is a naturally occurring volcanic glass that’s heated and bursts into fragments. A decomposes slowly neutral PH and is non-toxic.
It is an excellent material that improves aeration. It is lightweight and can escape from the pot while watering.
It can absorb water and fertilizer making it available to the plant for a long time.
Pumice is also a naturally occurring volcanic material. It is an excellent soil conditioner. It does not decompose over time or become compact.
Pumice has good absorption making sure the water and nutrients are available to the plant for a long time duration. It gives a neutral pH to the plant.
Vermiculite is made from heating mica. It has excellent water-absorbing property.
Vermiculite gives a neutral pH to the plant and does not decompose over time. It helps in providing good aeration as it is lightweight.
Send is inexpensive, reusable, and is usually used to balance heavy soil.
Sand has no absorption capacity providing excellent drainage. It is good for desert plants like succulents that like to be dry between watering.
Bark and wood chips
Bike decomposes slowly adding acidity to the soil as it decays. It provides good irrigation. It does not have water-retention property.
Wood chips have good aeration property. They retain moisture quite well. However, they decompose rapidly.
Calcined clay is good water absorbents and also helps to improve the drainage property of the soil. They are good for plants that need a good draining soil.
Let us now look into the fertilizers that are required by both potting soil and potting mix
Fertilizing the Indoor House Plants
Indoor plants need nutrition replacement during their growing period. The three main nutrition nutrients that the plant need is nitrogen Phosphorus and potassium. They are referred to as NPK with the balance formula being 10-10-10.
Along with these three nutrients, the plant also needs lesser amounts of calcium, sulfur, magnesium, and some trace elements.
Synthetic fertilizers are water-soluble and cheap. However, it is important to follow the instruction by the manufacturer regarding dosage.
Organic fertilizers are safe and provide all-round nutrients for the plants. They are slightly expensive when compared to synthetic fertilizers. A good example is compost.
Organic fertilizers contain natural ingredients like manure, worm casting, leaf mold, etc.
Preparing Potting Soil for Planting
If you want to make your own mix, follow the method below.
Please remember that if you wish to make your potting soil or use a store brought soil, make sure it is sterile.
Secondly, the pot should have good drainage holes for potting your plants.
Read up about your plant so you can know the exact requirement.
Plants needing moist soil do well in a soil-based potting medium, while the peat-based medium is good for others.
For a soil-based medium, mix sterilized soil and moist sphagnum moss in equal quantities. Add a gallon of perlite.
Next, adjust the mix by adding more soil/ peat moss or sand (depending on pH requirement) until a loose, well-draining potting soil is ready.
For a peat-based potting mix, take equal quantities of peat moss and perlite or vermiculite. Make the mix a little moist. Mix well and add to pots.
Potting soil or potting mix that is made fresh will last for a long time and give excellent results compared to a store-bought mix/soil.
Do not forget to add a bit of organic fertilizer for the ‘oomph’ look.
I hope I have resolved your query and you have found the answers you were looking for. Indoor plants are an awesome addition to homes. They not only purify our environments but also appease our mental health.
Do a little research about the requirement of your plant before selecting the soil. Next, select the soil based on all the information I have shared with you. Buy a potting mix or a potting soil or make a fresh one at home.
Make sure the soil or soil-less medium gives a good anchoring to your plant, proper aeration, water absorption with good drainage. The pH should be adjusted according to the plant species.
Fertilize it according to your plant growth and nutrition requirement and you have a happy and healthy plant that will last with you for a long time.
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