Why a complete pour works
Apply water across the entire surface until it flows freely from the drainage holes. If water channels around a dry root ball, repeat gently after a short pause and check whether the substrate is wet through. This both supplies moisture and carries some dissolved salts out of the pot.
What soaking changes
Immersion can rewet a severely hydrophobic root ball or help diagnose a pot that repels water. But routine soaking can reduce oxygen if the medium stays saturated, spread pests or pathogens between trees if water is reused, and fail to correct compacted or uneven substrate. It may also leave the center wet while the grower assumes the problem is solved.
Use observation, not a method slogan
Check moisture at more than one point and learn the pot’s weight, drainage and drying pattern. Frequency changes with species, weather, wind, container size, substrate and root mass. If salts are a concern, review water quality and fertilizer use; soaking is not a substitute for periodic flushing with suitable water.
Practical rule
Water thoroughly when the tree needs it. Reserve immersion for a diagnosed problem, then fix the substrate or irrigation issue that caused it.
This page is reconstructed from historical BlogBonsai material. Horticultural details should be interpreted for the species, season, climate and condition of the individual tree.