heel 3 
(hēl)
(hēl)tr.v. heeled, heel·ing, heels
To cover the roots of (a plant) with soil temporarily, as while preparing for a more permanent planting. Often with in: heeled in the apple saplings until the orchard had been laid out.
[Middle English helen, partly from Old English helian, to cover, heel in, and partly from Old English helan, to hide, conceal; see kel-1 in the Appendix of Indo-European roots.]