No matter the season, we always have something growing in pots. I’m a big fan of growing chilies, and growing them in pots allows me to start my chilies early inside, and then move them outside as the weather begins to warm up.
In addition to growing fruits or vegetables, pots are a great way of showing of flowers, succulents or really anything else you can think of.
Potting soil isn’t necessarily expensive, but we don’t all have bags of it lying around in the shed. So it can be quite tempting to dig up some soil from the garden and use it in your pots. The thing is, doing this can lead to failure further down the line.
Can you use garden soil for potted plants? You can do this, but we thoroughly recommend using bought potting compost instead. Garden soil can be full of pests, it’s heavy, it might not contain much in the way of nutrients and it can end up compacting and suffocating your plants.
As garden soil is a less than a great choice for potting, then what is a better choice? To answer this question we’ll take a close look at the ideal properties of potting soils and what commercially available solutions are able to best meet our needs.
What Makes a Great Potting Soil Great?
The perfect potting mix has certain qualities that ensure it’s great for a range of plants and can and will make a difference to any plants you have.
The best potting mixes must allow for water to easily flow and for equal distribution around your plant’s roots. It must be able to remain moist without retaining too much water. A dense soil mix can end up causing rot or drown your plant’s roots.
Your plant’s roots need to be able to breathe. Good potting soil is resistant to compacting and will still allow for micro air pockets for your plant’s roots to breathe. This is especially important as the soil in pots is prone to becoming compacted.
Despite what we’ve discussed above, the best potting soils are able to retain water without drying out too quickly. We need our plant’s roots to remain moist, so the soil should have a consistency of a rung our sponge.
Potting mixes that are bought will have an excellent balance of nutrients in order to promote vigorous and healthy plant growth. As standard, you can expect a potting mix to contain Nitrogen, Phosphorous, and Potassium, which are the cornerstones or plant Nutrients. You will also find a range of other less important trace elements.
While truly exceptional garden soils might be able to meet all these points, the chances are slim. You will likely find your garden soil is lacking in one or more areas and as such, any attempts to put it into a pot will be an upward battle.
Why Garden Soil is a Poor Choice for Pots?
Don’t get me wrong, I love the soil in our garden. I’ve worked hard over the years in order to enrich it with composted kitchen waste, we have a worm farm and we plant indigenous varieties and species that we know will do well in our soil.
However, I still wouldn’t use it in a pot or container. I’ll get into the reasons why below.
I challenge you to go into your garden right now and dig up some of your soil.
You will likely find that either your soil is very dark, heavy, and full of moisture. Or you’ll be at the other extreme and your soil will be dry and hard with barely and vegetative particles. If your soil falls into either one of these two categories, then your garden soil is already failing it being good for pots.
Regardless if your garden soil is wet or dry, it’s probably going to be very dense. If you take equal parts garden soil and equal parts potting compost, I can almost guarantee you that the garden soil will weigh much more.
It’s this density that prevents easy aeration of a plant’s roots when it’s used in a pot. This density can also lead to much greater water retention.
One of the great things about owning an established garden is that there’s a whole ecosystem at work maintaining and enriching your soil. In most gardens, everything is nicely balanced with predators and prey keeping things in check.
But, if you isolate only a small amount of garden soil in a pot, things can quickly go out of balance in this much smaller environments. Pests can get out of hand and you might find your potted plants are being overrun by bugs, fungus, and other things you wouldn’t normally have to contend with.
Any patch of the garden can contain hundreds if not thousands of seeds. These seeds are kept in check with established plants and lawns. In a plant pot, you might find that you’re facing an upwards battle ridding your pot of weeds if you use garden soil.
If you’re now in agreement that garden soil is a bad choice when it comes to potting, what’s a better choice?
What’s The Best Potting Mix
While there probably isn’t a perfect solution for everyone and what the best choice for you will depend a lot on what you’re planning to grow in your pots, I can make some general recommendations.
If you’re time and resources are limited then I thoroughly recommend buying a commercially made potting mix. Miracle Grow to make a perfectly capable potting mix that’s worked wonders for me over the years. You can check it out here.
If you’re feeling a little bit more adventures, then consider making your own potting mix. It’s easy to do and can save you a little bit of money in the long run.
Plus you’ll know exactly what your growing your plants in and feel like you’ve really put the effort in to give your plants to the best start in life.
We’re going to be using three main ingredients to create a balanced and light compost that will be suitable for almost any plant. The ingredients are Perlite, Vermiculite, and Mushroom Compost.
Perlite is produced in order to provide soil aeration. It’s mined amorphous volcanic glass and is naturally occurring lightweight inert material. You can even use it as a growing medium by itself.
Vermiculite is made from compressed dry flakes of a silicate material which is absorptive and spongy. It’s great at absorbing and retaining water.
Mushroom compost is an organic by-product of the mushroom farming process. As such it’s environmentally friendly, sustainable, and perfect for our potting mix. You might find other recipes online that call for Peat Moss. In our opinion, this should be avoided at all costs. Peat Moss is formed over thousands of years and is not a sustainable process.
Putting everything together is dead easy. We’ll use a 4-1-1 mixture, so 4 parts mushroom compost to 1 part perlite and 1 part Vermiculite.
I find the easy way to do this is by mixing all the parts together in a wheelbarrow. You don’t have to be super accurate about it, but as close to correct measurements as possible. When you’re mixing everything together give it a light watering with a hosepipe to make the mixture moist but not wet.
How to Use It
It’s worth giving some consideration to what you are planting in order to maximize the efficiency of your potting mix.
Shallow rooted plants are best kept in shallow pots or trays. Not only will this suite the plants better but it will also ensure you don’t waste any of your potting mixes.
If you only have deeper pots and shallow-rooted plants, then consider filling up the bottom half with other materials such as gravel, hay, or pebbles. This will save your potting mix and can provide better drainage for your plants.
If you’re planning on planting deep-rooted plants, then you’ll need larger pots and therefore you’ll be using a lot of potting mixes. There’s no way to avoid this.
Thankfully as we’ve been making our own potting mix, it should be relatively inexpensive to fill several large pots. Things tend to work out cheaper if you buy in bulk, so don’t be shy about buying large bags of perlite, vermiculite, and Mushroom Compost.
The only downside of this mix is that you will have to provide extra nutrients. Perhaps not while the plants are young, but certainly as they age and start to grow.
What Is the Best Fertilizer To Use With Potted Plants
As gardeners, we have more than a few choices when it comes to fertilizer.
If you have the facilities to do so, consider using something like a worm farm. Worm wee or worm tea is packed full of all the nutrients needed by plants and it’s a great way of disposing of kitchen waste.
If you don’t have access to a worm farm and can’t make one, then almost any commercially available fertilizer will do. The main decision is whether to choose organic or not.
For organic fertilizer, I like to use this one. It has a great profile and is from sustainably sourced. Two thumbs up in my book. Just add some to the potting mix as you’re adding it to your pots
For nonorganic fertilizer, you can use this one. As before, just mix it into the potting mix when you’re adding it to your pots.
If you have a compost heap at home, I can thoroughly recommend mixing in some homemade compost. It’s a great organic way of providing food for your plants and reduced your waste footprint.
Just bear in mind that Mushroom Compost will provide a lot of the nutrient needs for your plants, so you might need much more additional fertilizer.
How to sterilize potting soil?
Any commercially available potting soil won’t require sterilization. Soil from your garden may have a range of parasites and pathogens present that you would not want your plants in, so it’s best avoided.
How long does potting soil last?
As long as the soil is kept dry and sealed, then it should last indefinitely. The only issues that could occur are if it becomes infested with unwanted pests or if it becomes wet and begins to rot.