Because thou hast forgotten
shakach  (shaw-kakh')
to mislay, i.e. to be oblivious of, from want of memory or attention -- at all, (cause to) forget.
the God
'elohiym  (el-o-heem')
angels, exceeding, God (gods)(-dess, -ly), (very) great, judges, mighty.
of thy salvation
yesha`  (yeh'-shah)
liberty, deliverance, prosperity -- safety, salvation, saving.
and hast not been mindful
zakar  (zaw-kar')
to mark (so as to be recognized), i.e. to remember; by implication, to mention
of the rock
tsuwr  (tsoor)
a cliff (or sharp rock, as compressed); generally, a rock or boulder; figuratively, a refuge; also an edge (as precipitous)
of thy strength
ma`owz  (maw-oze')
a fortified place; figuratively, a defence -- force, fort(-ress), rock, strength(-en), (most) strong (hold).
therefore shalt thou plant
nata`  (naw-tah')
to strike in, i.e. fix; specifically, to plant -- fastened, plant(-er).
na`aman  (nah-am-awn')
pleasantness (plural as concrete) -- pleasant.
neta`  (neh'-tah)
a plant; collectively, a plantation; abstractly, a planting -- plant.
and shalt set
zara`  (zaw-rah')
to sow; figuratively, to disseminate, plant, fructify -- bear, conceive seed, set with sow(-er), yield.
it with strange
zuwr  (zoor)
to turn aside (especially for lodging); hence to be a foreigner, strange, profane; specifically (active participle) to commit adultery
zmowrah  (zem-o-raw')
a twig (as pruned) -- vine, branch, slip.