Root-bound plants seem to need more water, but they really need a bigger pot. The honest answer to watering root bound plants is that pouring on more will not fix the problem. The roots have filled the pot so tightly that there is almost no soil left to hold moisture, so the water has nowhere to soak in.
Watch one in action and the issue shows fast. You pour water at the top and it pours straight out the drainage holes within a few seconds. The surface looks soaked, yet the root ball stays dry in the middle where it counts. The plant looks watered while the roots stay thirsty.
Here is why this happens. The University of Maryland Extension says water moves through a pot-bound plant too fast to soak in. A healthy pot has open soil that holds moisture for hours. A bound pot is a dense mat of roots with little soil left. So the water runs through pot and out the bottom before the inner roots get a drink.
That dense mass can also dry into a hard plug. Once the root ball goes bone dry it turns hydrophobic, which means it repels water instead of soaking it up. New water then slides down the gap between the dry plug and the pot wall. The outside gets wet, the center stays parched, and the plant keeps wilting no matter how often you reach for the can. This is the trap most people fall into. They see droopy leaves, assume the plant is thirsty, and water again the next morning. The extra water just speeds out the bottom and the plant gets worse, not better.
There is a second problem hiding here too. Soggy runoff plus a crowded pot can rot the few roots that still work. A root-bound plant has so little soil that the small pockets of moisture left can stay wet against the roots for too long. So you can end up with a plant that is dry in the core and rotting at the edges at the same time. More water makes both halves of that problem worse.
Watch for these signs before you blame yourself for underwatering. They tell you the trouble is the pot, not your schedule.
Check the middle with your finger or a wooden skewer about an hour after you water. If it comes out dusty and dry while the rim feels damp, the soil cannot store water anymore. Roots poking out the bottom holes or coiling in a tight spiral seal the diagnosis.
The lasting fix is not more water. It is repotting into a container one or two inches wider. Slide the plant out, then loosen the matted roots with your fingers so they can spread into fresh soil. For a stubborn spiral, make three or four shallow cuts down the sides of the root ball with a clean knife. This sounds harsh, but it tells the roots to branch outward instead of choking themselves.
Set the loosened plant in fresh potting mix and water it well so the new soil settles around the roots. The first soak after repotting can take a while because the dry core needs time to rehydrate. Stand the pot in a tray of water for 20 to 30 minutes so the root ball drinks from the bottom up. After that, it will hold moisture the normal way again, and your watering can finally reach the roots that need it.
If you cannot repot right away, a bottom-soak buys you time. Set the whole pot in a sink or bucket with water about an inch deep and leave it for half an hour. The dry core pulls water up slowly through the drainage holes, which beats pouring from the top. This is a stopgap, not a cure. Spring or early fall is the best window to repot, so plan the real fix for then and keep bottom-soaking until you get there.
Read the full article: Root Bound Plants: Signs, Fixes, and Care
