From our perspective, the leaves are the most honest communicators of our distress. When we are overwatered, our roots begin to suffocate and rot in the waterlogged soil, unable to deliver nutrients or perform their functions. This systemic failure manifests in our leaves as widespread yellowing, often starting with the older, lower leaves. These leaves will feel soft, limp, and mushy to the touch. They may appear bloated and, in severe cases, will drop off the plant entirely without much provocation. Conversely, when we are desperately thirsty, our leaves send a very different signal. They lose their turgor pressure, becoming limp, wilted, and dry. They may feel papery or crispy, particularly around the edges. Instead of a generalized yellowing, our foliage often turns a dull green or brown and begins to curl inward or upward in an attempt to minimize surface area and reduce water loss.
You must look beyond what is visible above the soil to understand our true condition. The state of the growing medium is paramount. For an overwatered Calibrachoa, the soil will feel consistently wet, soggy, or even waterlogged for days on end. It may have a musty or unpleasant odor, a sign of anaerobic conditions and root rot. If you gently remove us from our pot, our roots will appear dark brown or black, feel slimy and mushy, and may fall apart easily. This is a critical, often fatal, condition. In stark contrast, the soil of an underwatered plant will be extremely dry, hard, and pulling away from the edges of the container. It will repel water initially rather than absorbing it. Our roots, in this case, are likely brittle, dry, and possibly shriveled, but they will not be rotted. They are simply dormant and waiting for the moisture they need to function.
Our energy and will to thrive are directly reflected in our growth and flowering patterns. Overwatering stresses our systems to a breaking point. The energy we would normally use for blooming is diverted to a futile struggle for survival against root rot and disease. Consequently, we will stop producing new flower buds, and existing blooms may wither and die prematurely. Our overall growth will be severely stunted. Underwatering also causes immense stress, but our response is different. To conserve our remaining water reserves, we will abort flowers and buds first, as they are the most energy-intensive structures to maintain. You will see a sudden drop of both buds and blooms. Our growth will also slow or halt, but this is a defensive mechanism. We are pausing our processes until life-giving water returns, at which point we can often recover more swiftly than from the ravages of root rot.
Our weakened state from incorrect watering makes us vulnerable to secondary attackers. The constantly damp conditions of overwatering create a perfect environment for fungal diseases. You may see fuzzy gray mold (Botrytis) on our flowers and leaves or other fungal growth on the soil surface. Fungus gnats are also a clear sign; their larvae thrive in moist organic matter, feeding on our already compromised roots. Underwatering weakens our cellular structures and makes us less resilient. While we may not attract moisture-loving pests, we become highly susceptible to infestations from sap-sucking insects like spider mites. These pests prefer hot, dry, and stressed plants, and they will quickly colonize our parched foliage, further exacerbating our decline.
