One of the most important thing in growing your own food in containers is the medium in which the plant grows. As vegetables plants need nutrition to grow and bear fruits, using plain soil as the medium is not enough. Hence a few items like compost are added to enrich the soil. A few other items may be mixed with it to get a desired feature in the medium. The growing medium thus prepared is called Potting Soil or Potting Mix. In this post I’ll take you through the various features of a good potting mix and then guide you on how to prepare your own Inexpensive Organic Potting Soil.
Features of Good Potting Mix
- Rich in Nutrients – When plants grow on ground, its roots can go quiet deep or spread in all directions in search of nutrients and water. In container gardening, the roots of the plants have limited space to grow. Hence you need to have a very rich medium in your pots so that the roots get enough nutrients.
- Water Retention – Due to limited size of pots water can dry out too quickly. But if the soil can retain water well, then you can minimize drying out problems.
- Drainage – While it is important for the organic potting soil to hold water, at the same time you have to make sure there is no water logging. Excess water should drain out easily from the pot, or else root rotting can take place.
- Structure – Some times when soil dries out it does not absorb water well. Such issues happen when there are not enough aeration in the soil. In other words the structure of the mix is not right. Your Organic potting mix should have particles of different granularity so that it is well aerated. But it should not have big lumps which affect proper root growth.
- Weight – The soil should be of light weight, so that you can move pots around easily. Moreover higher the weight higher the pressure on the structure where they are placed.
- Microbial activity – A good potting soil is always a living one. It means the potting mix should have enough microbial and insect activity. This keeps the plants healthy and helps them to grow well and give good yields.
- Free of pests and other pathogens – Most of the time potting soil has viral pathogens and dormant pests in them. If you grow plants in such mediums it damages not only the individual plant in the pot, but the entire garden as pest infestation can easily spread from one plant to the other.
- Optimum pH level – The pH level is a measure of the acidity of the soil. Generally most plants do well in neutral to slightly acidic organic potting soil mixes. Optimum pH reading can be between 6.0 to 7.0 in most cases.
What goes into our Organic Potting Soil
With the above features in mind here is a list of ingredients that go into our potting mix.
- Vermicompost or Earthworm Compost – Vermicompost is not only the best compost in terms of nutrients, it is also very good in terms of microbial activity and structure. Good quality vermicompost is the most important item in our potting mix. It is best to have your own vermicompost bin at home, but you can also purchase it from stores. Check whether the compost that you purchase from stores is earthworm compost or city compost. Do not go for city compost. While it is good enough if you are growing flowers, it just does not make the cut when you are growing vegetables.
- Home made compost – We always stress on organic waste recycling as a part of Organic Terrace Gardening. So even if you can not make earthworm compost at home, you should be making simple compost at home from organic wastes. In making compost at home its just not about recycling waste. You also are assured about the quality of the compost.
- Coco Peat – Coco Peat is the residual waste of the coconut coir industry. It is treated to remove salts from it and then sold in bags or in compressed form as bricks. When the bricks are soaked in water it expands to almost ten to fifteen times it size. Coco peat is very light in weight and has excellent water holding capacity.
- Garden soil – You can get red soil from nurseries or pick up soil from your backyard. If you can get hold of the clay from river beds, mix it with equal amount of red soil. Though river bed soil is great in terms of fertility but it is also too fine and hence can make the soil hard. Hence mix it with some red soil. Remove the lumps from soil by pounding it and then sun dry it for 5-6 days to kill pathogens.
- Cow dung manure – It is cheap and easily available and a great fertilizer.
- Neem Cake – Neem cake is the solid waste left over after neem oil extraction from neem seed kernels. Neem cake acts as a pest repellent and prevents pest and pathogen growth in the soil. It also acts as a great fertilizer.
- Oils seed cakes – Other oil seed cakes like mustard cakes, ground nut cakes are also great fertilizers.
- Fish Meal – This is a very potent fertilizer, but you can skip it if you are vegan or vegetarian.
- Amrut Jal -Amrut Jal is used to condition our organic potting soil by increasing the microbial activity in the potting mix and also enrich with nutrients.
- Earthworms – Small earthworms which burrow deep into the soil keep the potting mix loose and aerated.
- Wood ash – Wood ash is used to bring down the pH level of potting mix if required.
Organic Potting Soil Recipe
To make approximately 11-12 liters of potting soil follow the recipe below.
- Mix together 3 liters of sun sterilized soil, 3 liters of coco peat, 2 liters of vermi-compost and 2 liters of home made compost (or 3 liters of vermi compost).
- Add a liter of cow dung manure.
- Add a handful each of neem cake, mustard cake and ground nut cake.
- Add a handful of fish meal. Skip this if you are vegetarian.
- Mix this very well by turning the mixture several times over.
- Check the pH level of the mix. If mix is too acidic (pH reading is 5.5 or below), add a handful of wood ash. If it is alkaline (pH reading is over 7) add more compost.
- Now sprinkle about approximately half liter of Amrut Jal and give it a good mix. Amrut Jal is rich in microbial life and this step helps to increase the microbe count in the potting mix. To check the correct moisture level of the mix, try to make a ball in your palms. You should be barely able to make a very crumbly ball at the right moisture level. If moisture level is lower you’ll not be able to make the ball and if it is too high you’ll be able to make the ball easily.
- Store this mix in a container, cover it and let it rest for 2-3 weeks. Make sure the container is protected from direct sunlight and rain. Do not cover the container tightly. Air should be able to pass without any problem.
- Mix in some Amrut Jal every 4-5 days when the mixture starts to dry out to keep the moisture at a good level to encourage microbial activity.
- After about 2-3 weeks potting mix is ready to be used in pots. While preparing the pots drop in some earthworms in the pot. They are the best friends of your potting mix.
In the above process step 2 to step 9 are optional. But these steps will improve the quality of your Organic Potting Soil significantly. For germinating seeds in seed trays, substitute 2 liter of soil with 1 liter of vermicompost in the above recipe.
Maintenance of Soil in the Pot
As a plant grows and produces fruit in a container, the nutrients are depleted. Additionally sunlight and rain too leach out the nutrients from the potting mix. With time the soil tends to become acidic. To minimize these issues here are a few tips on how you can maintain the potting mix in your pots.
- Mulch your pot with organic material like dry leaves or dried sugarcane bagasse , wood chips etc. Not only it helps to retain moisture, it helps in maintaining a suitable micro climate for microbial life to flourish.
- Use cow dung based soil conditioner like Amrut Jal or Jeevamrut on a weekly basis.
- Check the acidity level of the potting soil once every 3 to 4 months. If too acidic add wood ash. If too alkaline add some compost.
- When an old plant has been rooted out from the pot, add vermi-compost, cow dung manure, neem cake and other oil cakes to the pot, sprinkle some Amrut Jal, cover it and leave for a couple of weeks before planting again.
In market potting mix price starts from approximately Rs 40/- per kg and can go up to about Rs 100/- per kg. When you build up a garden even in a balcony space housing about 10-12 containers, you need at least 50-60 kg of potting soil. Buying Organic Potting Soil from market will burn a hole in you pocket even for a balcony garden. With the given recipe you can get high quality potting mix for almost one fifth of the cost of potting mixes available in market. Moreover you know exactly what has gone into the potting mix when you make your own. You know its completely organic and chemical free. Many of the commercial potting mixes actually have growth hormones additives in them which is quite dangerous for your health. So go ahead and make your own Inexpensive and completely Organic potting soil for your garden. It takes a little effort, but totally worth it.