What is Potting Soil
Believe it or not, but potting soil does not actually contain any soil. Potting soil is soilless and mainly consists of one or more of the following: peat moss or coco coir, pine bark, perlite and vermiculite, with some brands adding in nutrients such as slow release fertilizers. Before we dive into the world of potting soils, here is a breakdown for all the ingredients and what characteristics and enhancements they add to make the best potting soil mix:
Peat Moss: Peat moss was introduced to gardeners around 1950, and it has greatly taken the gardening world by storm due to its impressive ability to hold on to vital nutrients that would usually get drained away. Peat moss also can absorb up to 5 times its weight in water, creating the ideal medium for seed germination and plant growth. Peat moss is composed mainly of decomposed moss which takes 1000’s of years to form, thus making it a non-renewable source that is non sustainable.
Coco Coir: Also known as Coco Moss or Coconut coir. Yes, you probably guessed it already! Coco coir holds the same amazing soil enhancements of peat moss, but is sustainable and is the environmental friendly option. Coco coir is made by decomposing the fibrous coconut shell.
Pine Bark: Pine bark enhances the soil by retaining moisture, protecting the soil against soil borne diseases and from extreme hot/cold weather conditions
Perlite: Perlite is a volcanic glass and a naturally occurring mineral that has a high water content. Perlite is extremely light and holds moisture, loosens up soil in order to improve root aeration. Thus, helps lighten and loosen soils. Perlite looks like white round styrofoam balls, but is as solid as a rock. A good potting soil can either have perlite, vermiculite or a mix of both.
Vermiculite: Vermiculite shares the exact same soil enhancement benefits as perlite, but consists of silicate material. It is beige in color and feels like sawdust.
Nutrients: Most popular commercial potting soils add slow-release fertilizers to maintain a nutritious soil for 3-6 months for a healthy plant growth. Fertilizers can be added manually later either via adding organic compost or chemical NPK fertilizer.
A decent potting mix is a combination of all the ingredients above in appropriate proportions, and will have the following characteristics:
Not sure which commercial potting soil to buy? We have tried over 100 different brands and reviewed the top 9 potting soils to help you make an informed buying decision, check it out!
Technically: NO! But Commercially: YES!
Technically speaking: The term “potting soil” is used for any soil regardless of the added soil enhancers. Once enhancers are added, that “potting soil” is then called “potting mix”
Commercially speaking: The term “potting soil” is used even when the product is a “potting mix” that contains all the soil enhancers (Perlite/Vermiculite, Peat Moss/Coco coir, Fertilizers). So if you were ever wondering “what is potting mix?”, now you know!
Fun fact: Potting Soil is also commercially sold as “Soilless potting mix”
Containers: No, mixing potting soil is not recommended at all for containers since garden soil is dense and has poor drainage. Garden soil is naturally aerated by works or grubs, and that is never going to happen inside your container. So if you are planting in containers, stray away from adding any garden soil. Not only will it compact your relatively small container, but it will also make the container less portable since garden soil is 20x heavier than potting soil.
Raised Beds: Yes, due to the nature of raised beds being not as portable as containers, with a much larger surface area, and is not frequently moved around; you can mix garden soil along with compost with your potting mix. In fact, there are lots of commercial potting mixes being sold and labeled specifically “For raised beds”.
Yes, we occasionally add compost to our potting soil as a soil amendment and it has been working wonders for us. Mixing compost with your potting soil will:
But keep in mind that adding too much compost may introduce unwanted problems. So stick to a maximum of 1:1 ratio, with 1 part compost to 1 part potting soil.
With our containers and raised beds, we usually add a 2-3 inch layer of compost every year. Ideally in early fall, in order to give the compost a chance to break down by spring and diffuse its magic into the soil.
Adding the annual layer of compost every year also helps in reducing weed growth.
Yes, potting soil does go bad due to the fact that peat moss’ lifespan is 2 years. It is not advisable to use expired potting soil since it will reduce your soil’s drainage and may cause root rot due to cutting off the oxygen supply in the soil.
So the next time someone asks you: “Does miracle gro potting mix expire?”, you know the answer.
You can determine that if you detect one or more of the following:
We have all been there with some extra potting soil left in the package. In order to properly store your potting soil and prevent it from rotting, growing mold or inviting those tiny unwanted gnats, it is recommended to store your extra potting soil in a dry area away from any direct sunlight. We always store our extra potting soil in their original bags (Sealed with tape) inside a protective container. Detergent containers work well, and if you want that extra protection then get one of those rubbermaid bins.
If I got a penny for everytime I answer this question, I would be a thousandaire!
I have had my bad share of experiences with unwanted bugs, fungus, weeds, surprisingly even from top potting soil brands that advertise a “Sterilized Potting Mix”. I always sterilize my potting soil prior to using them in my garden raised beds or indoor containers. Here are 4 methods you can use to sterilize effectively:
Do not heat your oven heat to anywhere above 200°F to avoid overcooking the soil (In that case it will not be suitable for planting)
You definitely can. In fact, a big portion of our beautiful garden plants have been grown this year reusing last year’s potting soil. Nothing wrong with saving some moolah.
But before you reuse your potting soil, there are a couple of steps you should take to revitalize your soil with nutrients and clean it up:
Mix in the following ratios together, and you have just made yourself the ideal potting mix:
Additional optional ingredients you can add:
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