Cloning, the process of taking a plant cutting to create a genetically identical copy, is most successfully performed during the vegetative growth phase. This period is biologically suited for root development, leading to high success rates and rapid growth. However, circumstances sometimes require a cutting to be taken after the plant has transitioned into the flowering phase. While more challenging and not the ideal practice, cloning a plant deep into its reproductive cycle is possible, provided the necessary reversion process is understood. The viability of this late-stage cloning depends on the plant’s internal hormone balance and the structural maturity of the stem material.
Hormonal and Structural Changes During Flowering
The difficulty of late-stage cloning is rooted in the plant’s shift in priorities from growth to reproduction. During the vegetative phase, the plant has high levels of the root-promoting hormone auxin, which naturally concentrates in the stem tips and helps initiate new root growth on a cutting. Once flowering begins, the internal hormonal balance changes dramatically, decreasing the concentration of auxins available for root formation. The plant begins to produce higher levels of hormones like gibberellins, which promote stem elongation and flower development. This hormonal change directs the plant’s energy away from root and shoot growth and toward reproductive structures. Simultaneously, the stem material undergoes lignification, a process that makes the tissues harder and woodier. This hardening makes it more difficult for the cutting to absorb water and form a callus. The meristematic cells, the actively dividing tissues where new growth originates, also prioritize flower production, further reducing the plant’s natural tendency to produce adventitious roots.
Defining the Practical Timeline for Cutting Viability
The flowering phase can be divided into three general stages that determine the likelihood of success.
Early Flowering (Weeks 1–3)
This stage offers the highest chance of success, with cuttings often rooting almost as quickly as those taken during the vegetative phase. The plant is still in a transitional state, and the hormonal shift is incomplete. The stem material retains a manageable level of flexibility and rooting hormones.
Mid-Flowering (Weeks 4–6)
This stage presents a significantly reduced chance of successful rooting, and the process becomes notably longer. The plant is firmly focused on flower production, and the stem material is beginning to stiffen. This requires a much longer time for the cutting to revert and establish roots.
Late Flowering (Post-Week 6/7)
Cloning at this stage is generally considered not worth the effort due to extremely low success rates. The plant has invested heavily in maturation, and the stems are often too woody. The energetic and hormonal resources needed for root initiation are severely depleted.
Navigating the Revegetation Process
Any cutting successfully taken from a plant in the flowering stage must undergo a process known as revegetation, or reversion, a process sometimes called “monster cropping”. To force this reversion, the new clone must be placed under a light cycle typical of the vegetative phase, such as 18 hours of light and 6 hours of darkness, or even 24 hours of continuous light. This extended light duration overrides the flowering signal that the cutting received from the mother plant. The feeding regimen should also be adjusted to include a higher ratio of nitrogen, which promotes lush, leafy growth rather than flower development. The initial growth of a revegetating clone will often appear mutated as the plant’s hormones rebalance. A common sign of this reversion is the appearance of single-bladed leaves or leaves with smooth, non-serrated edges. This abnormal growth can persist for four to eight weeks before the clone fully recovers and begins to produce normal, multi-bladed vegetative foliage.
Techniques for Successful Late-Stage Cloning
To maximize the rooting success of a flowering cutting, specific techniques must be employed. It is crucial to select the softest, least-lignified growth material, which is often found on the lower, lateral branches of the plant.
The use of high-strength rooting gel or hormone is a necessity, as the cutting contains lower natural levels of auxins. Rooting products formulated with higher concentrations of Indole-3-Butyric Acid (IBA) or Naphthaleneacetic Acid (NAA) provide the external hormonal signal required to initiate root formation.
Maintaining a consistently high humidity level, typically by using a humidity dome, is necessary to reduce stress on the cutting. Since the cutting cannot easily draw water without roots, high humidity prevents the leaves from drying out. Light intensity should be kept lower than normal to prevent stress and ensure the plant’s energy is directed toward rooting, not excessive photosynthesis.
Finally, using sterile cutting tools and making a clean, sharp 45-degree angle cut maximizes the surface area for hormone absorption and minimizes the risk of infection.