I was just starting some some cuttings from my pothos in water and thought it’s strange that they’ll survive in just water but perish w too much water in soil?
In: Biology
Ive always understood it as a matter of (poisonous) gas build up. Gas by-products are trapped in the soil and have prolonged exposure to the roots eventually causing death. In the water these gases are vented off easily.
ELI5- Soil holds in all the baddies so they cant escape but water lets them run away from the plant.
Too much water in soil allows bacteria and mold to grow and kill the roots. Hydroponic systems keep the water moving to keep that from happening.
Oxygen — It’s what plants crave!
Roots need to ‘breathe’, in fact, the more air they get the better, which is one of the reasons hydroponics can yield a superior crop. Water can contain different amounts of dissolved oxygen depending on conditions like temperature. Remember that even fish ‘breathe’ underwater, they just get their oxygen from the water.
Just like an aquarium, a hydroponic system must employ oxygenation techniques like bubble stones or a waterfall, or sprayers, or misters, etc… They also need to maintain certain temperatures because cooler water can absorb more oxygen. Because of these very high oxygen levels, plants are able to grow without a stabilizing medium, like soil.*
The problem with overwatering a houseplant is that the roots consume all the oxygen that the water had to offer, and then are unable to ‘breathe’. Without the period where the water dries and allows fresh air to enter the root system, followed by freshly oxygenated water, the roots will essentially drown.
Similarly, when propagating in water, the water needs to be changed frequently to maintain oxygen levels, or it’s likely to not work.
I’m not an expert or anything I just grew uh….. plants…. for a little bit and this is what I gathered.
*edit — I said
“Because of these very high oxygen levels, plants are able to grow without a stabilizing medium, like soil.”
But I think what I meant was that they don’t need to dry out, because of the high oxygen level.. which has nothing to with the medium.
Hydroponics always includes aeration so the roots can breathe periodically. The water may ebb and flow, be sprayed, or aerated in some way. If your cuttings are submerged long enough with no bubbles or aeration, rest assured they will “drown” too.
Sauce: Grown weed indoors for over 10 years. I prefer “soiless”, and let it dry out enough to breathe between waterings.
A lack of gas exchange around the roots in wet soil whereas running water allows it.
Also, if soil spaces are full of water they can be more easily compacted.
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