Best Potting Soil for Containers (and What to Never Use)
Potting mix is the single cheapest upgrade to your results. The right blend drains fast, holds moisture and keeps roots breathing.
Quick answer
Use a bagged potting mix (not potting soil, topsoil or garden soil) containing peat or coir, perlite and compost, or bark. For vegetables, choose a mix with added compost or slow-release feed. For herbs, succulents, and rosemary, add extra perlite or grit for faster drainage.
What is actually in a good mix
| Ingredient | Job |
|---|---|
| Peat moss or coco coir | Holds moisture and keeps the mix light |
| Perlite or pumice | Creates air pockets and drainage |
| Compost | Supplies nutrients and biology |
| Bark fines | Adds structure so the mix does not collapse |
| Slow-release fertilizer | Feeds plants for the first 4-8 weeks |
DIY container mix recipes
- All-purpose: 4 parts potting mix + 1 part compost + 1 part perlite
- Vegetables: 3 parts potting mix + 1 part compost + 1 part worm castings
- Herbs and Mediterranean plants: 3 parts potting mix + 1 part coarse grit or perlite
- Succulents: 2 parts potting mix + 2 parts grit + 1 part perlite
What not to use in pots
- Garden soil or topsoil — compacts, drains poorly, may carry pests and weed seed
- Pure compost — too dense and holds too much water on its own
- Gravel layers at the bottom — worsens drainage rather than helping
- Last year's spent mix with no refresh — nutrients and structure are gone
How much mix do you need?
| Pot size | Approx. mix needed |
|---|---|
| 1 gallon | 0.13 cu ft |
| 5 gallon | 0.7 cu ft |
| 10 gallon | 1.4 cu ft |
| A standard 2 cu ft bag | Fills about three 5-gallon pots |
Helpful tips
- Buy the largest bag you can carry — cost per litre drops sharply.
- Wet the mix before planting so it absorbs water evenly later.
- Store leftover mix sealed and dry so it does not turn into a weed nursery.
Common mistakes to avoid
- Grabbing a bag labelled topsoil or garden soil because it was cheaper.
- Adding gravel to the bottom of pots.
- Reusing old mix for hungry crops like tomatoes without amending it.
Frequently asked questions
Is potting soil the same as potting mix?
Not always. True potting mix is soil-free and drains quickly; some products labelled potting soil contain heavy field soil. Check the ingredient list for peat or coir plus perlite.
Can I use garden soil in containers if I add perlite?
It is still a compromise. Garden soil compacts over a season and can bring in pests. Fresh potting mix is worth the modest cost.
In short
Buy a quality mix, add compost for vegetables, and grit for herbs, and never bring garden soil onto a balcony.
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