Plant Growing Media Engine

Dirt is an AI tool for understanding, choosing and improving soil, potting mixes, substrates and other plant growing media.

Name the plants being grown, the medium the plants are growing in, or the problem occurring, and Dirt determines whether the growing medium suits the plant and what should change.

Describe a required root environment instead, and Dirt builds or modifies a mix from available components.

soil moisture meter and medium behaviour reader

• Interprets how a growing medium is behaving: water running straight through, a mix staying wet for days, crusting, cracking, repelling water, shrinking away from a container, compacting into a hard mass or collapsing after repeated use.
• Connects visible performance to texture, particle size, pore structure, organic content, decomposition, compaction, hydrophobicity, pH and salinity.

plant soil requirement matcher

• Matches the root environment a plant requires to a suitable soil, potting mix or substrate.
• Determines what a container, outdoor bed, raised bed, seed tray, propagation system, greenhouse, hydroponic system or field requires from a growing medium.

growing media component comparison

• Compares materials such as peat and coir, perlite and vermiculite, pumice and lava rock, bark and ordinary potting mix, garden soil and container media, or inert and organic substrates.
• Identifies which property each component changes and the tradeoff that comes with it, for perlite, pumice, coir, peat, bark, vermiculite, grit, sand, compost, biochar, charcoal and LECA.

percolation and infiltration checker

• Identifies what should change when a medium drains quickly but dries too fast, holds water but excludes air, or has lost the structure that once balanced both.

soil texture calculator

• Reads clay, sand, silt, loam, chalk, peat, stony ground and shallow soils for how particle size and aggregation affect infiltration, drainage, water storage, root penetration and compaction.

soil compaction tester

• Separates surface crusting, container collapse, compacted beds and deeper field or urban compaction.
• Determines which improvement options remain practical at the depth and scale of the damaged structure.

soil pH and lime application rate calculator

• Determines how pH is affecting nutrient availability.
• Recognizes nutrient lockout that resembles underfeeding.
• Identifies when the medium or water source is pushing the root zone away from the required pH range.

EC and salinity checker

• Assesses salt accumulation, deteriorated substrates and media changed by use, including organic material breaking into finer particles.

potting mix recipe builder

• Constructs a growing medium from available components according to the required behaviour.
• Adjusts an existing bagged mix where the product label does not deliver the needed drainage, aeration or moisture retention.

seed starting mix and potting-on selector

• Distinguishes low-nutrient, well-aerated media used while seeds germinate or cuttings root from richer growing-on mixes used after plants establish.

aroid, orchid and cactus substrate finder

• Selects specialty substrates for orchids and other epiphytes, succulents and cacti, aroids, carnivorous and bog plants, acid-loving plants, alpines and bonsai.

LECA and semi-hydro guide

• Explains what LECA, rockwool, perlite, pumice and other inert media supply when water and nutrients are managed separately.

raised bed soil calculator

• Builds and maintains raised beds through construction, component ratios, settling, organic matter breakdown, seasonal replenishment and long-term loss of volume.

soil health scorecard and improvement path

• Improves soils that cannot be discarded and replaced — compacted garden beds, stripped urban ground, market gardens and fields — using amendment, structure, organic matter, biology and time.

porometer and substrate testing at scale

• Separates interventions that make sense in one pot from those practical across a bed, greenhouse, market garden or field.

Enter the soil, potting mix, substrate, growing system or behaviour to be understood.

Where the composition is known, include the ingredients or proportions. Half coir and half compost that stays soaked, a bagged mix with extra bark, and mostly clay amended yearly each connect observed behaviour to a different structure.

Where the composition is unknown, describe what the medium does: how quickly water enters, whether water runs straight through or pools, how long the medium stays wet, whether the surface crusts, whether the mix shrinks or repels water, how hard the medium becomes when dry, whether the container has lost volume, and whether roots stay shallow.

Include the growing context — pot, raised bed, outdoor ground, greenhouse, propagation tray, hydroponic system, market garden or field — because a correction that is simple in a container can be impractical across an entire growing area.

diagnose how a medium is behaving

questions people ask:

"Why does water run straight through a peat-based mix?" · "Why does a planter stay soggy for days?" · "Why has a bagged compost set into a hard block?" · "Why won't a dried-out coir brick absorb water?"

work with soil texture and structure

questions people ask:

"Why does clay soil flood in winter and crack in summer?" · "How do I improve sandy soil so it holds more water?" · "What does loam actually mean?" · "Why can't roots penetrate a compacted bed?" · "Is poor drainage a texture problem or a compaction problem?"

balance drainage, water and air

questions people ask:

"What improves drainage in a heavy potting soil?" · "Can a mix drain well and still hold enough water?" · "Why does adding more leaf mould keep a pot wet?" · "Does gravel in the bottom of a pot improve drainage?"

compare components

questions people ask:

"What separates perlite from vermiculite?" · "Peat or coco coir?" · "Pumice or lava rock for a gritty mix?" · "What does composted bark add?" · "What does biochar actually do in soil?"

choose a medium for a plant

questions people ask:

"What growing medium suits echeveria?" · "What potting mix should I use for phalaenopsis?" · "What soil suits a monstera?" · "Is sphagnum suitable for blueberries?" · "What medium suits a Japanese maple in a pot?"

build or adjust a mix

questions people ask:

"How do I make an aroid mix?" · "How can bagged cactus soil be made to drain faster?" · "What ratio of topsoil to compost fills a raised bed?" · "How do I build a seed-starting mix?" · "Can pine bark, grit and worm castings make a useful mix?"

choose propagation and seed media

questions people ask:

"What mix suits rooting semi-ripe cuttings?" · "Why shouldn't rich soil be used for cuttings?" · "What makes seed compost different?" · "When should a rooted cutting move into a growing-on mix?"

work with pH and nutrient availability

questions people ask:

"What does soil pH actually affect?" · "Why are new leaves yellow on a plant fed weekly?" · "Can alkaline tap water push a substrate pH up?" · "Is poor growth caused by the medium or a lack of fertilizer?"

grow without soil

questions people ask:

"Can a pothos grow in LECA?" · "What does rockwool do in hydroponics?" · "Is expanded clay a growing medium by itself?" · "How is semi-hydro different from a conventional substrate?" · "What does an inert medium provide if it holds no nutrients?"

fill and maintain raised beds

questions people ask:

"How do I fill a new raised bed?" · "Why has a bed dropped several inches in a year?" · "Why does a three-year-old bed drain differently?" · "Should the fill be replaced or top-dressed?"

deal with compaction and degraded ground

questions people ask:

"The ground is hard across a whole allotment — what do I do?" · "How do I improve compacted urban soil?" · "How do I tell how deep compaction goes?" · "Will green manure fix a hardpan?" · "Why does water pool when the surface looks dry?"

check salinity and worn-out media

questions people ask:

"Why is there a white crust on a substrate surface?" · "Has an old orchid bark broken down too far?" · "Why did a mix that drained well start staying wet?" · "Can a used growing medium be reused?"

manage growing media at scale

questions people ask:

"How do I manage substrate in a commercial glasshouse?" · "How do I improve soil health across a market garden?" · "What can be done about compaction across an entire field?" · "How do I restore structure where replacing the soil isn't possible?"

the medium and its composition

• the soil, potting mix, substrate or growing medium being examined;
• the observed condition of the medium;
• the stated or likely composition;
• the soil texture or dominant particle characteristics where relevant;

how water and air move through it

• how the particle structure is affecting pore space;
• how quickly the medium drains;
• how much water the medium retains and releases;
• how much air remains available around roots;
• whether compaction, collapse or fine-particle accumulation is restricting the root zone;
• whether hydrophobicity is preventing the medium from rewetting evenly;

what each component is doing

• the role played by individual components or amendments;
• the strengths of the medium for the intended use;
• the limitations and tradeoffs created by the composition;

whether the medium suits the plant

• whether the medium suits the named plant or growing system;
• what would change the suitability assessment;

chemistry and deterioration

• whether pH is likely affecting nutrient availability;
• whether salt accumulation or degradation is altering performance;

the improvement path and its ratios

• what component should be added, reduced or replaced;
• mix ratios or construction guidance where a custom medium is needed;
• an amendment path when the existing medium can be retained;
• a replacement path when the existing structure is no longer practical to repair;

warning signs

• warning signs pointing to severe compaction, anaerobic conditions, structural collapse or salinity;

what changes with scale

• how the practical options change between a pot, bed, greenhouse, market garden or field;
• follow-up paths for deeper diagnosis, component comparison, recipe adjustment or longer-term soil improvement.

why no medium is good on its own

No growing medium is universally good. A medium performs well only relative to the plant grown in it and the system using it, and heavy clay, coarse mineral material, peat and sand each provide the correct root environment in one context and fail badly in another.

what amendment is actually closing

Amendment is an adjustment of fit. Changing a growing medium closes the gap between what the medium currently does and what the plant or system requires, which makes the useful question which property is mismatched and whether that property can be changed.

why particle size decides most of it

Particle size controls much of what roots experience. Particle size and arrangement create the pore network through which water and air move, and when fine material fills the larger pores, drainage, aeration and root penetration decline even though the ingredients have not changed.

why draining and holding water are not opposites

Drainage and water retention are not simple opposites. A well-structured medium moves excess water away while retaining usable moisture in smaller pores, so the target is a distribution of pore sizes appropriate to the roots and growing system.

the two reasons water disappears fast

Fast water movement means two different things. Water can pass rapidly through a genuinely coarse, open medium, or channel around a dry hydrophobic root ball without wetting it. The symptom looks similar, while one case calls for greater moisture retention and the other for successful rewetting.

why the bag does not tell you how a mix behaves

The product label does not determine physical behaviour. A bag marked cactus mix, orchid mix or potting soil can contain a particle distribution that performs poorly for the intended plant, so what the medium does after watering matters more than the printed category.

why stones at the bottom of a pot change nothing

A drainage layer does not remove the perched water problem. Changing abruptly from fine potting medium to coarse stones at the bottom of a container does not make water leave the upper layer sooner, because container drainage depends on the structure of the growing medium itself.

when sand makes the problem worse

Adding sand can make a dense medium denser. Fine sand occupies the spaces between larger soil particles rather than opening them, so whether sand improves a medium depends on particle size and proportion.

why a mix stops being the mix you made

Organic substrates change as they age. Bark and other organic particles break down into smaller material, and the same mix loses large air spaces, retains water longer and behaves very differently from the medium originally placed in the container.

when feeding cannot fix a deficiency

pH can make available nutrients functionally unavailable. A medium can contain nutrients and still produce pale or stunted growth when root-zone chemistry prevents uptake, and adding more fertilizer does not resolve a nutrient that is present but chemically unavailable.

why urban ground needs structure before fertility

Poor urban soil is often a structural problem before a fertility problem. Construction traffic, loss of topsoil and repeated disturbance leave ground dense, shallow and low in functional pore space, and nutrients alone cannot restore the physical environment roots need.

how to read a medium without knowing what is in it

Soil behaviour can be read through the plant and the water. Pooling, rapid channeling, prolonged wetness, shallow roots, repeated root loss, surface crusting and changes in drying speed all provide evidence about conditions below the surface even when the exact composition is unknown.

why the same problem has different answers at different sizes

Scale changes which solutions remain available. A failed potting mix can be discarded and rebuilt, a raised bed can be progressively amended, and a compacted field or degraded urban site has to be improved in place, which brings depth, machinery, organic matter, biology and time into the decision.

the forms growing media take

Growing media take many forms:

• garden soils: clay, sandy, silty, loamy, chalky, peaty, stony, shallow and mixed soils used for outdoor growing;
• potting mixes: bagged and custom container media, including mixes that drain too quickly, remain wet, compact, shrink, become hydrophobic or deteriorate with age;
• container substrates: media designed around the restricted root volume and perched water behaviour of pots and planters;
• raised bed media: topsoil, compost and amendment blends used to fill new beds and maintain established beds as organic matter decomposes and volume settles;
• seed-starting media: fine, consistent media that maintain moisture and aeration around germinating seed;
• cutting and propagation media: low-nutrient, open substrates used while new roots form, including perlite, coir and bark combinations;
• potting-on media: mixes used after seedlings or rooted cuttings move beyond propagation into a more durable growing environment;
• orchid and epiphyte substrates: bark-based, highly aerated media for roots adapted to exposed or loosely supported conditions;
• succulent and cactus media: mineral-heavy, rapidly draining substrates built around short wet-dry cycles and high root-zone aeration;
• aroid media: coarse container mixes combining moisture retention with large air spaces around roots;
• carnivorous and bog-plant media: substrates built around persistent moisture and the chemical conditions required by plants adapted to nutrient-poor wet habitats;
• acid-lover media: substrates and soils where root-zone pH and the resulting nutrient availability are central to plant performance;
• alpine and bonsai substrates: specialist mineral and mixed media where particle size, drainage, aeration and structural stability are deliberately controlled;
• soilless substrates: LECA, rockwool, perlite, pumice, lava rock and other inert or largely inert media used without conventional soil;
• semi-hydro and hydroponic media: root-support materials used where water and nutrients are supplied separately from the substrate;
• organic amendments: compost, aged manure, bark, wood-derived materials, coir and peat used to alter structure, water holding, fertility or organic matter;
• mineral amendments: perlite, pumice, vermiculite, grit, sand and lava rock used to change pore size, drainage, aeration or water retention;
• biochar and charcoal: carbon-based amendments whose usefulness depends on the intended structural and growing context;
• compacted soil: containers, beds, fields and urban ground where pore space has been lost and water infiltration or root penetration restricted;
• hydrophobic media: dry organic mixes that repel water or allow water to channel around the root ball instead of rewetting evenly;
• saline media: soils or substrates affected by accumulated salts from irrigation water, fertilizer or repeated container use;
• degraded media: substrates whose particles have broken down, structure has collapsed or physical behaviour has materially changed with age;
• urban and disturbed soils: stripped, compacted or structurally damaged ground where rebuilding the root environment requires more than adding fertility;
• greenhouse and nursery substrates: media used at volume where consistency, particle distribution, drainage, aeration and repeatable performance matter;
• market garden and field soils: larger growing areas where compaction, organic matter, structure and amendment are managed without replacing the soil profile.