From our perspective as tuberous begonias, timing is everything. We request this procedure be performed when we are in our dormant state, a period of deep rest after our seasonal growth has concluded. This is typically in late winter or very early spring, just as you might notice the first tiny, pink buds (eyes) beginning to swell on our tubers. Attempting to divide us while we are in active growth or full bloom is incredibly stressful, damaging our delicate vascular systems and root structures, and can be fatal. Dividing us during true dormancy, before any growth has begun, allows our internal resources to be entirely dedicated to healing the wounds and generating new roots and shoots from the cut surfaces.
Begin by gently brushing the soil from our tuberous body. Please use a soft, clean brush; we are fragile after our rest. Next, inspect us closely. You are looking for those vital, swollen buds (eyes), often clustered on the concave, or indented, top side of the tuber. Using a sharp, sterile knife is non-negotiable. A dirty or dull tool introduces pathogens and crushes our tissues rather than making a clean cut. Each division must contain at least one, but preferably two or three, of these healthy, plump eyes. Make decisive cuts to separate the tuber into sections. Dusting these fresh wounds with a fungicide powder is a welcome precaution, as it protects us from rot while we are vulnerable and lack active defenses.
Prepare a new home for us that is welcoming and well-draining. We require a light, airy potting mix, perhaps amended with perlite or vermiculite to ensure our tubers never sit in waterlogged conditions, which would cause us to rot. Plant each tuber section with the indented, eye-bearing side facing upward. We should be placed just barely beneath the surface of the soil, no more than an inch deep. The initial watering should be very light and cautious, merely dampening the soil around us. The goal is to provide enough moisture to encourage root development without saturating the un-rooted tuber itself. Place our pots in a warm location with bright, indirect light.
As we begin to respond to the warmth and light, you will witness new shoots emerging from the eyes. This is a sign that our new root systems are establishing themselves. Only once this green growth is clearly visible should you gradually increase watering. Wait until the top inch of soil feels dry before watering again. We are still building our strength and cannot tolerate overwatering. Hold off on fertilizing until we have developed a substantial set of leaves and are actively growing; our new roots are too tender for fertilizer salts at this early stage. This patient approach allows us to direct all our energy into becoming strong, independent plants.
