How to Mix Your Own Potting Soil (And Why You Should)

Walk into any garden center and you’ll see dozens of bags of potting soil. All-purpose mix, cactus mix, orchid mix, seed-starting mix, moisture-control mix. It’s overwhelming.

Here’s the truth: most store-bought potting soil is fine. But it’s designed to work for the widest range of plants, which means it’s not optimized for any specific plant.

Mixing your own soil lets you control drainage, aeration, and moisture retention. You can build the perfect soil for each plant’s needs. And it’s cheaper than buying a dozen specialized mixes.

Plus, it’s oddly satisfying to mix your own soil. Like baking bread, but for plants.

Why Store-Bought Soil Isn’t Always Ideal

It’s designed for the average plant. Most commercial potting soil is formulated to work for common houseplants. If you’re growing cacti, orchids, or semi-hydro plants, generic mix won’t cut it.

It stays wet too long. Many store-bought mixes contain a lot of peat moss or coco coir, which hold water. Great for plants that like moisture. Terrible for plants that need fast drainage.

It compacts over time. After a few months, cheap potting soil breaks down and becomes dense. Water doesn’t drain well, roots can’t breathe, and plants struggle.

It’s expensive for what you get. A bag of premium potting mix costs $15-20. You can make your own high-quality mix for half that price.

The Three Key Components of Potting Soil

Good potting soil has three functions:

  1. Drainage - allows excess water to escape quickly
  2. Aeration - provides oxygen to roots
  3. Moisture retention - holds enough water for roots to absorb

Different plants need different ratios of these three properties. The key is balancing them correctly.

Base ingredients:

Peat moss or coco coir - Retains moisture, provides structure. Peat is acidic and slow to break down. Coco coir is renewable, pH-neutral, and breaks down faster.

Perlite - White volcanic glass that improves drainage and aeration. Lightweight and doesn’t break down.

Vermiculite - Expands when heated, retains moisture and nutrients. Good for seedlings and moisture-loving plants.

Coarse sand - Adds weight and drainage. Use horticultural sand, not beach sand or fine sand.

Bark (orchid bark or pine bark) - Adds drainage and aeration. Breaks down slowly. Great for aroids and orchids.

Pumice - Volcanic rock that adds drainage and aeration without breaking down. Heavier than perlite.

Compost or worm castings - Adds nutrients and beneficial microbes. Use sparingly (10-20% max).

Activated charcoal - Absorbs toxins and impurities. Optional but helpful for terrariums and sensitive plants.

Basic Mix for Most Houseplants

This is a good all-purpose mix that works for pothos, philodendrons, monsteras, spider plants, and most common houseplants.

Recipe:

  • 2 parts peat moss or coco coir
  • 1 part perlite
  • 1 part compost or worm castings (optional)

Why it works: Retains enough moisture for most plants while providing decent drainage. The perlite prevents compaction.

How to mix:

  1. Measure ingredients by volume (use a scoop or bucket)
  2. Dump everything into a large bin or tarp
  3. Mix thoroughly with your hands or a trowel
  4. Moisten the mix slightly before potting (dry mix is dusty)

Fast-Draining Mix for Succulents and Cacti

Succulents and cacti need soil that dries out quickly. They’re adapted to arid environments and will rot in regular potting soil.

Recipe:

  • 1 part peat moss or coco coir
  • 2 parts perlite
  • 1 part coarse sand or pumice

Why it works: The high ratio of perlite and sand creates fast drainage. Water flows through quickly and the soil dries within a few days.

Optional add-ins:

  • Small lava rock or crushed granite for extra drainage
  • A handful of activated charcoal for freshness

Aroid Mix for Monsteras, Philodendrons, and Pothos

Aroids (plants in the Araceae family) like chunky, well-draining soil that mimics their natural environment - climbing on trees with roots exposed to air.

Recipe:

  • 1 part peat moss or coco coir
  • 1 part perlite
  • 1 part orchid bark

Why it works: The bark adds large air pockets. Roots get both moisture and oxygen. The mix drains fast but retains enough water for thirsty aroids.

Pro tip: For larger aroids like mature monsteras, increase the bark ratio to 2 parts bark, 1 part coco coir, 1 part perlite.

Orchid Mix

Orchids (especially epiphytic orchids like Phalaenopsis) don’t grow in soil at all. They’re air plants that cling to trees. They need a mix that’s almost entirely bark with very little moisture retention.

Recipe:

  • 4 parts orchid bark
  • 1 part perlite
  • 1 part charcoal

Why it works: The bark chunks provide structure without staying wet. Orchid roots need to dry out between waterings.

Pro tip: Use medium or large bark chunks, not fine bark. Fine bark stays too wet.

Seed-Starting Mix

Seeds need a light, sterile mix that retains moisture without getting waterlogged.

Recipe:

  • 1 part peat moss or coco coir
  • 1 part vermiculite
  • 1 part perlite

Why it works: Vermiculite retains moisture so seeds don’t dry out. Perlite adds drainage. No compost or fertilizer (which can burn delicate seedlings).

Pro tip: Moisten the mix before sowing seeds. Dry seed-starting mix is hydrophobic and hard to wet evenly.

Semi-Hydro Mix (LECA Alternative)

If you’re growing plants in semi-hydro or LECA, you don’t need traditional soil. But if you want a hybrid approach, this mix works.

Recipe:

  • 1 part coco coir
  • 2 parts perlite
  • 1 part orchid bark

Why it works: Fast-draining, airy, and doesn’t compact. Roots have access to both moisture and oxygen. Great for transitioning plants from soil to semi-hydro.

How to Customize Your Mix

Once you understand the basics, you can adjust ratios based on your plants’ needs.

If your soil stays wet too long: Add more perlite, pumice, or bark.

If your soil dries out too fast: Add more coco coir or vermiculite.

If your soil compacts: Add more perlite or bark to improve aeration.

If your plants need nutrients: Add compost or worm castings (10-20% of the total mix).

If you’re in a humid climate: Increase drainage by adding more perlite or sand.

If you’re in a dry climate: Increase moisture retention with more coco coir or vermiculite.

Where to Buy Ingredients

Peat moss / Coco coir: Garden centers, hardware stores, online. Coco coir bricks are cheap and compact.

Perlite: Garden centers, hardware stores. Buy in bulk if you’re mixing a lot of soil.

Vermiculite: Garden centers, hydroponic stores.

Orchid bark: Garden centers (orchid section), online. Buy large bags for better value.

Pumice: Bonsai suppliers, garden centers, online.

Coarse sand: Hardware stores (look for “horticultural sand” or “sharp sand”), not playground sand.

Compost / worm castings: Garden centers, make your own, or buy from local composters.

Pro tip: Buy ingredients in bulk and store them in sealed bins. You’ll save money and always have soil ready when you need to repot.

Mixing Tips

Use a large bin or tarp. Mixing soil is messy. Do it outside or in a garage.

Wear gloves and a mask. Perlite dust and dry peat moss can irritate your lungs.

Moisten before use. Dry mixes are dusty and hard to work with. Lightly moisten the mix before potting.

Mix thoroughly. You want an even distribution of ingredients. No clumps of peat or pockets of perlite.

Store leftovers properly. Keep mixed soil in a sealed bin or bag. Add a little moisture to prevent it from drying out completely.

Is It Worth the Effort?

If you only have a few plants, buying pre-mixed soil is fine. Mixing your own probably isn’t worth it.

But if you have a growing collection (and let’s be honest, once you start, you can’t stop), mixing your own soil makes sense.

You’ll save money. You’ll have the exact mix your plants need. And you’ll have the satisfaction of knowing you built the perfect home for your plants from the ground up.

My garage has bins labeled “Aroid Mix,” “Succulent Mix,” and “General Mix.” When I repot a plant, I grab the right bin and I’m done. No trips to the store. No wondering if this bag of soil will work.

It’s one of those things that seems like extra work until you do it. Then you wonder why you didn’t start sooner.

The Bottom Line

Mixing your own potting soil isn’t complicated:

  • Start with a base (peat or coco coir)
  • Add drainage (perlite, pumice, or sand)
  • Add aeration (bark or perlite)
  • Adjust based on your plants’ needs

Your plants will thank you with faster growth, healthier roots, and fewer problems.

And you’ll have the smug satisfaction of knowing you’re not just a plant owner - you’re a plant engineer.

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