Should I feed my freshly cut, unrooted clones, or wait until the roots get established?

When propagating with clones, its best to only use clean, sterile water for both misting or fogging the tops of the clones and for saturation of the propagation medium (or if using a water culture propagation system). Freshly cut clones have no roots with which to take up nutrients, so feeding is not required until the first young roots have formed and then nutrients should be first applied at quarter strength, increasing to half vegetative strength as the clones become more developed.

Once ready for planting, the clones then need to be hardened off with full-strength vegetative nutrient solution to help prevent any transplant shock. While very low levels of minerals (such as those which might be naturally be present in a water supply), won’t generally harm newly cut clones, the use of other fertilizers can cause issues with increasing the water loss from the cut stem surface and restricting water uptake by the cutting which can lead to wilting of the remaining foliage on the clone.

The clone can manufacture some of its own food supply (photoassimulate) during the propagation process which is why clones are provided with a low level of light and have some leaf area retained for this process. However, leaves also lose moisture during the cloning process, which is why we restrict leaf area by removing or cutting back some of the foliage and provide misting or fogging for the plant tops. Using clean and preferably sterile water (such as reverse osmosis water) is also a good idea when taking clones, as the cut surface is prone to infection by pathogens under the damp conditions maintained for cloning.