How To Add Minerals To Your Houseplant Soil Naturally

Published on December 12, 2025 • Aaron – BIOS Nutrients

Minerals are the structural backbone of plant health.

They influence everything from leaf colour and stem strength to root development, resilience, and how well plants can handle pests and disease pressure. Light and water are important, but if the mineral side of your houseplant soil is weak, you’ll eventually see it in yellowing leaves, weak growth, and plants that never quite reach their potential.

Out in nature, soil is constantly getting fresh minerals from rock weathering, rain, and decomposition of organic matter. In a pot, that system is restricted. Most potting mixes start with a limited mineral reserve, and every time you water, some nutrition leaves through the drainage holes.

TL;DR: Quick Summary

Most potting mixes slowly run out of minerals, especially if you’re only using synthetic liquid fertilizers that flush through the pot. Plants need at least 17 essential elements to reach their full potential, and likely benefit from many more, considering seawater contains 70+ elements.

• Rebuild the mineral base with broad-spectrum rock dusts (like basalt, calcium silicate, soft rock phosphate) at low, measured rates.
• Add compost or worm castings for organic matter and microbes.
• Include plant and ocean meals (kelp, alfalfa) to round out trace minerals and gentle nutrition.
• Inoculate with mycorrhizal fungi, which are vital partners that help roots actually access those minerals.
• Dial in structure by plant type:
  • Succulents & cacti – very fast-draining, high mineral, low–moderate organic.
  • Aroids – chunky, airy, moisture-retentive, nutrient dense.
  • Epiphytes – ultra airy, with enough fines and compost to support biology.

Instead of throwing soil out, you can re-use and re-mineralize it: adjust structure, add minerals, compost, and mycorrhizae, and top-dress castings throughout the year. You’re treating soil as something you build and maintain, not something disposable.

In this guide we’ll go through:

• Where minerals come from in soil
• How plants absorb nutrients from soil
• Why microbes and mycorrhizae are vital for mineral absorption
• Natural ways to add minerals to houseplant soil
• Specific mineral-rich soil recipes for:
  • Succulents & cacti
  • Aroids
  • Epiphytes

This will build potting mixes that support plant health for years and help prevent deficiencies, as well as pests and disease.

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Essential Elements And The “Full Spectrum” View

Plant nutrition science currently recognizes at least 17 essential elements that plants need to complete their life cycle: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum, nickel, and chlorine.

That’s the established baseline.

At the same time, seawater contains 70 or more elements, including a wide range of trace nutrients and metals in very small concentrations. There is ongoing discussion and research around additional elements that may have subtle or conditional benefits in plant and soil systems, even if they aren’t on the official “essential” list yet.

So I feel like a more complete statement would be:

Plants need at least 17 essential elements to grow to their full potential, and may benefit from many more considering sea water contains 70 or more elements.

Rather than chasing every element individually, it makes sense to use broad-spectrum mineral sources—rock dusts, composts, plant and ocean meals—and let the plant–microbe system decide what to pull from that buffet.

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Where Minerals Come From In Soil

Weathering: Rock Slowly Becoming Soil

Natural soil begins with rock.

Over long periods, rock is broken down and chemically altered through:

• Physical processes
  • Freeze–thaw cycles
  • Roots pushing into cracks
  • Abrasion from wind, water, and ice
• Chemical processes
  • Rock reacts with water, oxygen, and natural acids (carbonic acid from CO₂, organic acids from roots and microbes).
  • These reactions gradually dissolve and transform minerals, releasing nutrients like calcium, magnesium, potassium, and others.

What you end up with is a mix of:

• Sand – large particles, high drainage, low nutrient-holding
• Silt – medium texture, moderate nutrient-holding
• Clay – very fine particles with high surface area that can hold and release nutrients

Together with organic matter, these mineral fractions form the structural and nutrient-holding framework of soil.

Rain, Water, And Nutrient Movement

Rain and irrigation water don’t just wet the soil; they move nutrients.

• Rain and water carry dissolved nutrients to plant roots.
• As water infiltrates the soil, it picks up nutrients from decomposing organic matter and mineral surfaces and moves them toward the root zone.
• Excess water can also wash some nutrients deeper or out of the system entirely.

In nature, there is a balance: weathering, dust, and organic matter add nutrients; leaching and plant uptake remove them.

Organic Matter And Nutrient Recycling

Organic matter—dead roots, leaves, manures, compost—is the recycling system.

As microbes and fungi break down organic matter, they:

• Release nutrients back into the soil water
• Build stable humus that can hold nutrients and water
• Improve soil structure for better air and root penetration

In houseplant soil, we mimic this with compost, worm castings, and plant-based meals.

What Changes In A Potting Mix

In typical peat- or coco-based houseplant mixes:

• There is less true mineral material than in a natural mineral soil.
• There is very little deep-profile rock weathering.
• Rain and tap water mainly act as leaching agents, carrying nutrients out of the drainage holes.

If you never add new minerals, the nutrient bank account slowly runs down.

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How Houseplants Absorb Nutrients From Soil

You don’t need to become a soil chemist to understand the basics.

Nutrients move toward roots in three main ways:

1. Water Flow Toward The Roots

When a plant transpires (loses water through its leaves), it pulls water up from the soil:

• You water from the top.
• Water moves through the soil and toward active roots.
• Dissolved nutrients travel with this water and arrive at the root surface.

This is a major pathway for more mobile nutrients.

2. Movement From High To Low Concentration

When roots are actively feeding in one area, nutrient levels around them drop.

• Nutrients gradually move from zones where they’re more concentrated to zones where plants have used them.
• Over time, this helps replenish the area close to the root surface.

The key idea: a well-blended mix with minerals and organic matter spread throughout gives roots more consistent access to nutrients as this natural movement happens.

3. Roots Exploring New Soil

Roots aren’t static; they’re constantly growing and branching.

• As they move through the pot, they push into fresh pores and channels.
• They come into contact with new surfaces of compost, fine mineral particles, and amendments that are holding onto nutrients more loosely.

For this to work, the soil needs good structure and aeration so roots and microbes can physically occupy more of the volume you’ve built.

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Microbes & Mycorrhizae: Vital Partners In Mineral Absorption

Microbes and mycorrhizal fungi are not an add-on in this approach—they’re vital to how minerals become plant-available.

In a living soil, even in a pot, you have:

• Bacteria
• Fungi (including arbuscular mycorrhizal fungi)
• Actinomycetes
• Other microscopic life working in and around the root zone

What Microbes Actually Do

Microbes:

• Break down organic matter into simpler plant-available forms
• Release natural acids that slowly dissolve tiny mineral particles, including rock dusts
• Transform nutrients between forms and keep them in circulation
• Help build granular structure that improves drainage, air space, and root penetration

Arbuscular mycorrhizal fungi (AM fungi) take things even further:

• They connect directly to root cells.
• Their fine fungal threads extend far into the soil, accessing phosphorus and micronutrients in tiny spaces roots alone would miss.
• The plant trades sugars to the fungi in exchange for better access to nutrients and water.

Multiple studies show that mycorrhizal fungi can supply a significant portion of a plant’s phosphorus in lower-fertility soils and improve uptake of several other nutrients.

If you think of minerals as charge stored in a battery, microbes and mycorrhizae are the wiring and the trigger that release that stored energy as a pulse when the plant actually needs it. Without that connection, a lot of what you add just sits there.

In this system:

• Minerals are the raw material
• Microbes and mycorrhizae are the vital partners doing the processing
• Roots are the end users

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Natural Mineral Inputs For Houseplant Soil

Rock Dusts: Long-Term Mineral Backbone

Rock dusts are finely ground rock materials that release nutrients slowly.

Typical guideline ranges for basalt-type rock dust products:

• 0.5–3 lb per cubic foot of soil mix
• Roughly 8–48 g per litre of soil, or about ⅛–¾ cup per cubic foot, depending on density

Many blended rock dust products (for example, mixes of basalt, calcium silicate, soft rock phosphate, and related materials) are suggested at around 3 cups per cubic foot (roughly 2 lb / cu ft), which works out to about 32 g per litre.

For indoor houseplants, I prefer to stay toward the low end of those ranges because:

• Pots are small and easy to overdo.
• We’re usually combining multiple mineral sources in one mix.

As a starting point for most houseplant mixes:

• Basalt or broad-spectrum rock dust: ~5–10 g/L
• Wollastonite or soft rock phosphate: up to ~5 g/L

You can increase slightly toward the mid-range once you’re comfortable and have seen how your plants respond.

Plant & Ocean Meals: Biological Mineral Sources

Plant-based and seaweed meals add both minerals and organic matter that microbes can work on.

Good options:

• Kelp meal
  • Seaweeds concentrate a wide range of micronutrients and beneficial compounds from seawater.
  • Kelp meal is mild in NPK but excellent as a trace element source and biological support at moderate rates.
• Alfalfa meal
  • Provides nitrogen, potassium, calcium, magnesium, and additional micronutrients.
  • Contains natural compounds that can support plant growth and microbial activity.

Starting rates (per litre of soil):

• Kelp meal: 2–5 g/L (about ½–1 tsp)
• Alfalfa meal: 5–10 g/L (about 1–2 tsp)

Used together with compost and rock dusts, these help round out the mineral profile and feed the biology.

Compost, Worm Castings, And pH-Balancing Minerals

• Compost or worm castings
  • Provide slow-release nitrogen and a broad spectrum of minerals.
  • Introduce and feed microbial communities that help unlock nutrients from rock dusts and meals.
• pH-buffers
  • Dolomitic lime (calcium–magnesium carbonate) and calcium silicates (e.g., wollastonite) help keep peat-heavy mixes from drifting too acidic over time while supplying calcium and magnesium (and silicon in wollastonite).
  • Typical horticultural rates are 3–7 g/L for peat-based mixes, with houseplant mixes usually staying near the low end unless you have clear pH data.

Mycorrhizal & Microbial Inoculants (Vital In This System)

Because we’re intentionally building mineral-rich, living mixes, mycorrhizal fungi and microbial inoculants are central:

• Apply arbuscular mycorrhizal inoculant directly to the root zone at planting or repotting.
• Pair this with compost or castings to provide a broader microbial community.
• Avoid heavy, frequent doses of high-salt synthetic fertilizers that can interfere with mycorrhizal relationships.

If the minerals are the stored charge, the biology is what actually lets that stored energy move through the system and into the plant when it’s needed.

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Mineral-Rich Houseplant Soil Recipes By Plant Type

Different plant groups need different structures and water dynamics. Below are three tuned recipes, all per 10 L of finished soil.

Each recipe:

• Uses a specific base structure suited to that plant type
• Adds slow-release, natural minerals
• Relies on mycorrhizae and microbes to keep nutrients flowing

1. Succulents & Cacti: Mineral-Rich, Fast-Draining Mix

Goal: High drainage, strong mineral support, modest organic fraction.

Base (10 L):

• 3 L potting mix or coco coir
• 3 L coarse horticultural sand or very fine grit
• 2 L pumice or perlite
• 1 L small gravel or expanded clay
• 1 L compost or worm castings

Mineral amendments:

• 2 tbsp basalt or rock dust blend (≈20–30 g total for 10 L)
• 1 tbsp wollastonite or small amount of soft rock phosphate
• 1–2 tsp kelp meal
• 1 tbsp alfalfa meal

Biology:

• Mycorrhizal inoculant on roots at potting

This mix gives succulents and cacti:

• Excellent drainage and air space
• Just enough organic matter for microbial life
• Slow-release mineral support without staying wet for long periods

2. Aroids (Monstera, Philodendron, etc.): Chunky, Living Mineral Mix

Goal: Chunky, well-aerated, moisture-retentive, nutrient dense.

Base (10 L):

• 3.5 L potting mix or coco coir
• 2.5 L chunky orchid bark or large coco chips
• 2 L perlite or pumice
• 2 L compost or worm castings

Mineral amendments:

• 3 tbsp basalt or rock dust blend (≈30–45 g total for 10 L)
• 1 tbsp wollastonite or soft rock phosphate
• 1–2 tsp kelp meal
• 1 tbsp alfalfa meal

Biology:

• Mycorrhizal inoculant dusted into the root zone during potting

Aroids respond well to a mix like this that stays airy but has a strong nutrient and mineral foundation for big leaves and strong stems.

3. Epiphytes (Hoyas, Many Orchids, Some Ferns): Airy, Mineral-Supported Mix

Goal: Very airy, low–moderate fines, strong microbial and mineral support.

Base (10 L):

• 3 L chunky orchid bark
• 2 L large perlite or expanded clay
• 2 L coco chips or coarse coconut husk
• 1.5 L potting mix or coco coir
• 1.5 L compost or well-sifted worm castings

Mineral amendments:

• 2 tbsp basalt or rock dust blend
• 1 tbsp wollastonite
• 1–2 tsp kelp meal
• 1 tbsp alfalfa meal

Biology:

• Mycorrhizal inoculant placed where roots are likely to grow

For epiphytes, structure is the priority—lots of air around the roots. Minerals and biology slot into that structure rather than dominating it.

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How To Re-Use And Re-Mineralize Old Houseplant Soil

You don’t have to throw soil away every time you repot. You can rebuild and re-mineralize it.

Re-Using Soil Step-By-Step

1. Collect old soil in a bin.
2. Remove large roots, sticks, and debris.
3. Check texture:
   • If compacted → add more aeration (perlite, pumice, bark).
   • If too loose and “empty” → add more compost or castings.
4. Treat this as your base and re-amend with:
   • Rock dusts and plant meals at the same per-litre rates for the plant type you’re mixing for
   • Fresh mycorrhizal inoculant at potting
5. Adjust moisture and, ideally, let the mix sit for a bit so microbes can re-establish.

You’re treating soil as something you build and maintain, not something disposable.

Top-Dressing Compost Or Worm Castings

Practical usage rates:

• 4–6" pot – 1–2 tablespoons of worm castings or compost on the surface
• 8–10" pot – 2–4 tablespoons
• 12"+ pot – about ¼ cup or a small handful

Gently scratch the castings into the top layer and water as usual.

If you want to top-dress rock dust as well, use a small pinch per small pot, scaling up to 1–2 teaspoons for a large pot, staying within the low-rate guidance.

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Common Mistakes When Adding Minerals To Houseplant Soil

Over-Liming

Repeatedly adding dolomitic lime without tracking pH or plant response can:

• Push soil too alkaline
• Reduce iron, manganese, and other micronutrient availability

Use lime when:

• You have a high peat fraction
• Your water is very soft
• Symptoms and/or pH testing point toward low pH and calcium/magnesium issues

Using Rock Dust As Bulk Filler

Rock dust belongs in tablespoons and grams, not as a major volume of the mix.

Too much can:

• Make soil heavy and reduce drainage
• Shift pH more than intended
• Create an unbalanced mineral environment

Starting at the low end of typical rock dust ranges is a safer choice for indoor containers.

Expecting Minerals To Fix Light, Watering, Or Pest Issues

Minerals are fundamental, but they won’t fix:

• Plants in very low light
• Chronic overwatering and root rot
• Severe pest outbreaks

They are one pillar in a system that also includes light, water, air, microbes, and good root health.

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Abbreviations & Terms Used

• N, P, K – Nitrogen, Phosphorus, Potassium
• Ca – Calcium
• Mg – Magnesium
• pH – Measure of how acidic or alkaline something is (lower = more acidic, higher = more alkaline)
• Mycorrhizae / AM fungi – Arbuscular mycorrhizal fungi that partner with roots and help with nutrient uptake