A conservation nursery in Canterbury described native plants as having superpowers. That sounded like a stretch, so I checked what fire and flood experts say a plant can and cannot do.
The Department of Conservation runs one commercial plant nursery, at Motukarara in Canterbury, and its job is to grow native plants to help restore the Canterbury Plains and Te Pātaka o Rākaihautū, Banks Peninsula. On 2 September it put out a release calling those plants "plants with superpowers".
I am suspicious of the word superpower when it is attached to something that cannot move. So I went to find out what a plant is genuinely capable of, and where the claim stops being true.
Start with flooding, because that one is easier to see.
When rain lands on bare ground - a mown paddock, a slope with nothing on it - it runs straight downhill, picks up soil on the way, and arrives somewhere all at once. That is what makes a flood dirty and sudden.
Plants change the timing. Leaves catch some rain before it lands. Roots hold soil so it does not slide away. Rough, planted ground slows water down instead of letting it sheet off. A planted stream margin does something similar sideways: it holds the bank together and filters what washes through it.
Nothing there stops water. Every bit of it delays water and reduces what the water carries. In a flood, delay is not a small thing. Delay is the difference between a stream rising over an hour and a wall of mud arriving in five minutes.
Fire is the one where I expected the claim to fall apart, and it half did.
Fire and Emergency New Zealand's advice is not "plant natives and you will be safe". It is about something called defensible space: the managed area right around a building where you cut down how much fuel there is for a fire to use. Move firewood away from the wall. Clear dry material from gutters and from under decks. Keep grass short. Then, and only then, choose what you plant, because some plants burn far more readily than others.
Plants with high moisture in their leaves and less dry, dead material in them are harder to ignite and burn less fiercely. Plants full of oils and dry litter can carry fire towards a house. So a well-chosen plant is a slower fuel, not a shield. That is a real advantage and it is much less exciting than a superpower.
The word I would use instead is buffer. A buffer does not stop the thing coming. It gives you time, and time is what emergency services need.
There is one more thing the nursery is doing that has nothing to do with houses. The Canterbury Plains were once covered in native forest and shrubland, and very little of it is left. Growing local plants from local seed and putting them back is restoration - rebuilding the thing that used to be there - and it happens to also slow water and hold soil. The protection is a side effect of putting a landscape back together.
So my answer, after a day of reading: plants can meaningfully reduce how much damage fire or flood does, and they cannot make a house safe. Anyone who tells you a plant will save your house is selling you something. Anyone who tells you plants make no difference has not looked at a bare hillside after heavy rain.
Question for the reader
Go and stand outside where you live, and look at it the way a fire or a flood would.
Where would water go if it rained hard for two days? Find the lowest point you can see. Is there anything between the top of the slope and that point - grass, trees, a garden, a fence, a drain - or is it a clear run? If it is a clear run, that is the answer to why some streets flood and the next one does not.
Now do the fire version. Walk right around the building and look for anything dry and touching it: firewood stacked on the wall, long grass, dead leaves in the gutter, a pile of prunings under the deck. Each of those is fuel with a bridge to the house.
Here is the harder question, and it is the one adults actually fight about. Planting for protection takes years to work and costs money now. The flood might come next winter or in forty years. Councils have to decide whether to spend today on something that might pay off long after everyone involved has moved on - or spend it on something people will notice this year.
If you were the one deciding, how would you weigh a benefit you cannot see against a cost you can? And who should pay: the person whose house is protected, the whole street, or everyone in the country?
If you get a chance, ask someone who has lived through a flood. They tend to answer that one very quickly.