Plants do signal to one another. That much is well established, and some of the clearest examples come from Australian bushland. What is much less settled is the popular version of the story - the "wood wide web" of trees consciously sharing resources and warning their neighbours - which has been seriously challenged in recent scientific reviews. Both halves of that are worth knowing, because the real findings are interesting enough without the embellishment.
What is genuinely established
Airborne chemical signals
When many plants are damaged by insects, they release volatile organic compounds into the air. Nearby plants detect these compounds and respond by ramping up their own chemical defences before being attacked themselves. This has been demonstrated repeatedly across many species and is not controversial.
Australians experience one version of this constantly without thinking about it. The blue haze that gives the Blue Mountains their name is eucalyptus oil vapour - volatile compounds released by the trees, scattering light in the atmosphere. Those same classes of compounds are part of how plants signal.
Calling in reinforcements
Some plants under attack release compounds that specifically attract the predators and parasitic wasps that prey on the insects eating them. The plant is not communicating with its neighbours here so much as advertising a meal, but the effect is real and measurable.
Root signalling
Plants release chemicals through their roots that affect nearby plants, sometimes suppressing competitors and sometimes altering their growth. Root systems also detect the presence of neighbouring roots and adjust their own growth accordingly, which is why plants spaced too closely often perform worse than the spacing alone would explain.
Fungal networks exist
Mycorrhizal fungi genuinely form partnerships with plant roots, and they genuinely connect the roots of different plants underground. This is not in dispute. Around 90 per cent of land plants form these relationships, and they substantially improve nutrient and water uptake.
What is contested
The popular story goes considerably further: that mature "mother trees" recognise their own seedlings, deliberately send them carbon through fungal networks, and pass warning signals to their neighbours.
A significant 2023 review in the scientific literature examined the evidence behind these claims and found it far weaker than the public discussion suggests. The reviewers concluded that the popular narrative had outrun the data, with results from a small number of studies being over-generalised, and effects that could be explained more simply being attributed to deliberate sharing.
None of that means fungal networks are unimportant - they clearly matter enormously to plant nutrition. It means the specific claims about trees intentionally nurturing their offspring through them are not well supported yet, and honest reporting should say so.
What this means in an Australian garden
Practically, quite a lot follows from the well-established findings even without the contested parts.
- Soil biology is real and worth protecting. Mycorrhizal fungi improve nutrient uptake, and repeated digging, fungicide use and heavy fertilising all disrupt them. Mulching and minimal cultivation help.
- Do not over-fertilise natives. Australian plants evolved with these fungal partnerships in phosphorus-poor soil. High-phosphorus fertiliser damages the partnership as well as the plant.
- Spacing matters more than it looks. Plants detect and respond to neighbouring roots, so overcrowding reduces growth beyond simple competition for water.
- Diverse planting is more resilient. A monoculture hedge shares pests efficiently; mixed planting does not.
- Established trees create conditions - shade, leaf litter, soil biology - that make it easier for other plants to grow beneath them, even without any deliberate sharing.
Australian plants and chemical defence
Australian flora is unusually rich in defensive chemistry, which is a large part of why it smells the way it does.
- Eucalypts produce oils that deter most herbivores. Koalas are among the few animals that can process them, and even they are limited to certain species.
- Melaleucas and leptospermums produce the antimicrobial compounds behind tea tree oil and manuka honey.
- Acacias increase tannin levels in their foliage in response to browsing, making the leaves less palatable.
- Grevilleas and other Proteaceae form specialised cluster roots that release compounds to extract phosphorus from soils where it is almost unavailable - an adaptation to some of the oldest, poorest soils on earth.
That last one is a genuinely remarkable piece of chemistry, and it is also why those plants are damaged by ordinary garden fertiliser. They are built to extract phosphorus that is not there, and they cannot switch the mechanism off when it suddenly is.
Where the science is heading
Research into plant signalling is active and moving quickly. Electrical signalling within plants, root-level chemical detection, and how mycorrhizal networks actually function are all under investigation, and the picture will keep changing.
The reasonable position for a gardener is that plants sense and respond to their environment in far more sophisticated ways than was assumed a few decades ago, that some of this involves genuine signalling between plants, and that the more dramatic claims should be treated as interesting hypotheses rather than settled fact.
Frequently asked questions
Do plants really communicate with each other?
They exchange chemical signals, yes. Damaged plants release volatile compounds that neighbouring plants detect and respond to by increasing their own defences. This is well established. Whether that constitutes communication in any intentional sense is a separate question.
Is the "wood wide web" real?
Mycorrhizal fungal networks connecting plant roots are real and important for nutrition. The popular claims built on top of them - mother trees recognising and deliberately feeding their own seedlings - were seriously questioned by a 2023 scientific review that found the evidence much weaker than public discussion suggests.
Can plants warn each other about insects?
There is good evidence that plants attacked by insects release airborne compounds and that neighbouring plants respond by boosting their defences. Whether the releasing plant is warning others or simply reacting to damage is not resolved.
How does this affect how I garden?
Protect soil biology by mulching and digging less, avoid high-phosphorus fertiliser on Australian natives, space plants properly, and plant diverse species rather than large monocultures. All follow from the well-established findings.
Why are Australian plants so chemically defended?
Ancient, nutrient-poor soils make each leaf expensive to produce, so it pays to defend it. That is why eucalypts, melaleucas and tea trees are so aromatic, and why grevilleas evolved specialised roots to extract phosphorus that is barely present.
Do plants feel pain?
Plants detect and respond to damage through chemical and electrical signalling, but they have no nervous system or brain, and there is no evidence they experience anything comparable to pain. Response to injury is not the same as sensation.
Working with your soil, not against it
The most practical takeaway is that soil is a living system worth looking after. Browse our Australian natives range, which is adapted to Australian soil biology, or potting mixes, mulches and fertilisers for improving what you have.
Related reading: soil types explained and native vs exotic plants.
