Getting the scoop right on potting soil is important if you’re looking to grow plants in containers!
With a specific formulation of ingredients, which varies and (is proprietary in terms of exact percentages) from one brand to the next, potting soils are designed to provide container plants with a balanced growing medium.
What’s the Difference: Plants in the Ground vs. Pots and Containers?
POTS & CONTAINER – Think about it from your plant’s perspective, the key difference is that grown in a container, your plant’s root system is confined to a small volume of soil, and that soil needs to supply all of your plant’s water and nutrient needs.
In a containerized situation – whether it be a planter, urn, pot, window box… your plant will need more water and more food (fertilizer).
IN THE GROUND – This is a different story, generally speaking, because in the ground your plant’s root system isn’t necessarily confined. Roots can travel in search of water and nutrients.
Though off topic here, it is common to amend your garden soil with organic matter like “compost” which helps improve the health and quality of your soil.
But, back to it… the soil you buy for container plants, is specifically formulated to plant directly within and it also has a balanced pH. You want to make sure then to buy potting soil or potting mix.
Just make sure the word “Potting” is on the bag.
If you are more DIY and want to make your own potting soil, here are some good recipes to check out.
Why Does it Matter, Potting Soil or Planting Mix?
Planting mix, is designed to mix in with your regular garden soil, it’s an amendment. So if you buy this for a planter let’s say (instead of potting soil) the mix could burn your plants.
But you could use planting mix to topdress a planted area to provide nutrients and organic matter. Just add 1 inch or more of the amendment directly on top of your garden soil. You can do this also with potted plants that get hungry, like roses, fuchsias. Just add some to the top of the soil, but be careful to always keep the soil away from the trunk because this can cause rot.
Note: Sometimes soil labels can be very confusing. The best advice is to either know what you’re buying, or to read the package, ingredients and instructions before buying. Careful not to confuse potting soil with packages or supplies that say: “Planting Mix,” “Topsoil” or “Soil Amendment”.
What Makes Up a Good Potting Soil?
In general, a good potting soil will have a high water and air holding capacity, and, should meet the needs of your plant’s roots for nutrients, and support.
Having ingredients that help the mix hold water and nutrients – Might include a course aggregate like: perlite, vermiculite, or red lava. Peat moss and coconut coir are organic materials also used for the same purpose.
I love coconut coir, (AKA: coco coir) which is a sustainable byproduct of coconut processing. This is made using fibrous husks which either get decomposed or ground to produce a material similar to peat moss: better than peat though, because no need to drain peat bogs to get it. 🙂
Organic matter and amendments are also key ingredients in good potting soil. These may include: leaf mold, worm castings, chicken manure, compost, etc.
STRANGE FACT: Not much soil is used in potting soil, strange right? But then imagine how much MORE HEAVY the bag would become…
Potting Soil Tailored to Plant Types
Choosing a good potting soil can be a lot like matchmaking and will depend upon factors like…
- Container size – A small container like a balcony window box or hanging basket can dry out fast! This may be okay if you are growing succulents. Otherwise, choose a potting soil that is moisture retentive with ingredients like, coconut choir or peat moss.
- Plant choice – For succulents, Christmas cactus and cactus in containers, go with a specially formulated fast draining soil. I would recommend going with cactus potting soil.
- Location type – If you’re concerned about the weight of heavy planters on your balcony, deck or rooftop, choose your planters and soil accordingly. There are stylish lightweight pots and planters made of fiberglass and look for lightweight potting soil.
Sometimes Adding Ingredients to your Potting Soil is Smart!
If you want to better tailor your potting soil to the needs of your plant here are some good ones, and how they can be used:
To increase water retention and porosity add coco choir.
Coco coir also makes an excellent growing medium for hydroponics and orchids.
Horticultural pumice is a favorite of cactus and bonsai growers, this material increases drainage while promoting high water retention. I occasionally add in red lava to my potting soil mixes to improve drainage and aeration.
Growing Vegetables in Pots or Raised Beds?
You are what you eat…
If you are planning to grow vegetables I would recommend going with organic potting soil. Certified organic soils are put to strict standards. Compare that to conventional potting soils which may contain synthetic wetting agents and chemical fertilizers.
In case you live somewhere without a store that carries potting soil (or in a city without a car) I’ve added my link to Amazon which offers a great selection. Check out Black Gold Organic Potting Soil. It has 4 stars and great customer reviews. Look for vendors that offer free shipping.
p.s. Here’s a broader selection of potting soils and mixes that can be found on Amazon.