Abstract: The invention relates to the use of a crushed material obtained from at least one part of rocket plants, for example of the genera Eruca (Eruca Eruca vesicaria, etc.), Diplotaxis (Diplotaxis erucoides, Diplotaxis tenuifolia, Diplotaxis muralis, etc.), Bunias (Bunias erucago, Bunias orientalis, etc.), Erucastrum (Erucastrum nasturtiifolium, Erucastrum incanum, etc.) or Cakile, in order to promote plant growth or root growth.