What is plant callusing?
Root production starts as soon as a stem is cut from its parent. This is called wound shock. The first reaction is the formation of callus tissue which protects the wound. Next, roots are produced. The formation of callus is necessary prior to rooting, although roots do not grow from the callus, but from the cambium immediately behind it. Rooting is encouraged by moisture, warmth and good aeration. However, there are times when over-callusing happens which makes it harder for your cutting to grow proper roots.
Over-callousing can be overcome by changing the water out once the over-callusing becomes noticeable.
An option to prevent it is to add long dry cycles. Approximately 45- 60 minutes off at least every couple hours. Once the callus forms it will start to yields amazing roots without having to change out the water.