Are you struggling to choose the best potting soil for container vegetable gardening?
In this post, I’ll show you different soil mixes that are perfect for your containers. Plus what to look for in quality soil for container-based planters.
Let’s dive in.
What Is The Best Soil For Growing Vegetables In Containers?
Don’t feel intimidated when shopping for the best soil for container gardening.
Container soils are often referred to as soilless or artificial media because they contain no soil at all.
They are often composed of various things such as peat, vermiculite, bark, coir fiber (ground coconut hulls) in a variety of recipes depending on the manufacturer and the type of plant you are planting.
The heating of potting mixes during processing get rids of weed seeds, pests, and disease.
Read the label to make sure the soil mix is ideal for your purpose.
Your vegetable plants will thrive in organic potting mixes made for containers.
If the nursery owner allows you to open the bag for consistency check, that would be great.
For most outdoor plants, choosing a good quality, all-purpose soil mix for containers is usually the best option.
If you are looking for the perfect soil for your vegetable container gardening, pay attention to the following criteria.
- the medium is light and fluffy
- it has good drainage, but also holds moisture
- it’s porous so that water and air can easily reach the roots of the plants
- there aren’t any weed seeds germinating in the bag, or tiny bugs flying around it
- there’s not a large amount of bark or sand in the mix
- it’s moist but not soggy, and the smell is pleasant
What Is A Good Soil Mixture For Container Gardening?
Forget about the best potting mix for awhile.
Vegetables will grow well if you follow these rules when making a potting mix.
Lots of Air
Roots love lots of air.
Excellent soil, even in the garden, is 25% air.
In pots, however, water tends to accumulate at the bottom, despite drainage holes.
The smaller the pore spaces of the soil in the pot, the higher that water layer will reach.
Larger pores, formed by adding mineral aggregates to potting soils, readily admit water into the ground, then carry it through the medium and out the bottom.
Then, all those large, empty spaces can fill with air.
So, make sure your potting mix is airy.
All you need is lots of spaces between particles.
Perlite, vermiculite, calcined clay (kitty litter), and sand are the mineral aggregates most commonly used in potting soils.
Have you wondered why you veggies in container dry out so fast?
It is your soil mix.
You can reduce watering frequency if your potting mix can hold water.
Plant roots hate spikes in moisture levels.
They prefer constant moisture all of the time.
So, get soil mixture that dries out slowly.
When you add water to the vegetable garden each time, it will wash some nutrients out the bottom of the container.
It makes sense to get a potting mix that can keep the nutrients longer.
At the same time, you don’t need to fertilize the plants so often.
Loose and porous mixtures not only make a container lighter to move.
But they transport water, fertilizer, and air to plant roots more quickly, and allow for proper drainage, which is essential for container gardening.
If you’re using lots of containers in your balcony for vegetable gardening, you want the potting mix to be light.
If you have tall veggie plants, then you need heavy soil for support.
In short, make sure the soil for your vegetable containers has proper aeration, drainage, and nutrient retention.
How To Make Your Own Vegetable Container Garden Mix
You only need 3 things for a DIY potting mixture.
Preferably get garden soil from a home center, which is pre-sterilized to remove weeds or disease.
Sphagnum peat moss. The producer harvests it from bogs. Then drain it. So, you end up with dry moss with a light brown color. You may need to add some water before mixing the potting soil.
Perlite, vermiculite, or sand. Perlite is made by heating bits of a glasslike mineral until they expand into puffy, lightweight particles. It holds no water, aside from the little that clings to the surface of each particle.
Watch the video below on DIY Potting / Container Soil Mix for Vegetable
We use organic materials in potting mixes such as peat moss, sphagnum moss, compost, bark chips, and coir.
They cling to some of the water that the aggregates are helping to drain.
They also provide nutrients and a proper pH balance for your plants.
Use equal parts of peat moss, potting soil, and vermiculite, perlite, or clean sand. Fill the containers to within an inch or two of the rim.
To determine how much potting mix you’ll need, figure:
- 3 pints of soil per 6-inch pot
- 3 1/2 gallons of mix per 12-inch pot
- 6 1/2 gallons of mix per 20-inch pot
How Much Compost Do I Add To Potting Soil?
Recommended maximums are 30% to 50% compost in a soil blend, but no more than 30% compost in containers.
Remember that potted plants tend to dry out quickly.
A higher percentage of compost helps hold more moisture, decreasing the rate at which the soil dries out.
How Much Perlite Do I Add To Potting Soil?
Add perlite to make up around 10-50% of the total volume of potting mix.
If you want better water retention and don’t plan on using a lot of extra nutrients, then 10-20% perlite is your target.
Too much perlite can cause the nutrients leach out faster from the soil as water drains through easily.
If you plan to add a lot of nutrients for high yield of your vegetable containers, aim for 30-50% perlite.
Can You Mix Potting Soil With Garden Soil?
The perfect potting mix does not contain actual soil or garden dirt.
It doesn’t offer enough air, water, or nutrients to container-grown plants.
Even healthy garden soil can compact in the containers.
It will cause poor drainage and airflow within the soil.
Don’t think the topsoil is lacked moisture even though it appears dry.
Down a few inches, you’ll find a waterlogged layer of soil.
It can stop your plants from absorbing the needed nutrients.
If you haven’t tested the pH level of the garden soil, it can be too acidic for growing vegetables.
Garden dirt is not free of harmful fungus and microbes, not mentioning weed seeds. All these are bad for your veggie plants.
You rarely find garden dirt in commercial mixes. It’s hard to get a steady supply that is consistent in quality and free of toxins such as herbicide residues.
If you want to use the garden soil, it needs to be modified or amended.
Use one part garden soil, one part peat moss and one part perlite or coarse builders sand.
Don’t use fine beach sand or play sand.
The Do’s And Don’ts For Container Soil Mix
Commonly found in diapers, hydrogels (water crystals) are small beads that expand when in contact with water.
The problem with hydrogels is that they don’t release it to plant roots.
So don’t add them to your vegetable containers.
Rocks to Improve Drainage
Most gardeners think putting rocks at the bottom of the container helps drainage.
Sadly, they only reduce the growing space of the container.
Avoid putting rocks, or clay pot shards or Styrofoam peanuts in the bottom.
Containers With No Drainage Hole
Your container needs drainage holes.
If you have those containers without holes, drill some.
Mycorrhizal fungi provide plant roots in the ground with water and phosphate.
And if you do not fertilize your container enough, there might be some benefit.
But over-fertilizing is so common that the fungi provide no benefit.
And if you add too much phosphorus, the mycorrhizal fungi will die.
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