The Collaborative International Dictionary of English v.0.48:

Root \Root\ (r[=oo]t), v. i. [imp. & p. p. Rooted; p. pr. &
   vb. n. Rooting.]
   1. To fix the root; to enter the earth, as roots; to take
      root and begin to grow.
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            In deep grounds the weeds root deeper. --Mortimer.
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   2. To be firmly fixed; to be established.
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            If any irregularity chanced to intervene and to
            cause misappehensions, he gave them not leave to
            root and fasten by concealment.       --Bp. Fell.
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WordNet (r) 3.0 (2006):

rooting
    n 1: the process of putting forth roots and beginning to grow