How come many houseplants will rot if their roots sit in waterlogged soil but when you propagate plants you let the roots sit in water to grow?

Question

How come many houseplants will rot if their roots sit in waterlogged soil but when you propagate plants you let the roots sit in water to grow?

In: Biology

Answer 1

I do hydroponics / aeroponics with plants, but mind you: only as a hobby. This is a hobbyists explanation. (Initially wrote this as a reply, but then decided it might stand on its own? You decide.)

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Root rot is also a risk when you are “only” using water / a nutrient solution. Root rot is partly caused because the roots do not get enough oxygen, and partly can be / is caused by bacteria.

To keep the risk low, you keep the temps of your nutrient solution low and blow lots of air through it, using air stones like from aquariums. You can also add a bit of H2O2 to help keep your nutrient solution free from bacteria causing rot. At the same time this increases oxygen levels in your solution to prevent the roots from “suffocating”.

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You CAN hang your plants directly into the reservoir / the nutrient solution, this is called “Deep water culture”.

Or you hang them into a container or pipe of some sorts and spray or drip your nutrient solution onto the roots, then let it flow back into the reservoir and repeat the cycle.

There is also a technique called “Ebb and Flow” which basically means you flood the plant roots with nutrient solution completely, then let it flow back into the reservoir and give the plant roots some time to dry off. Repeat cycle.