Webster’s 1913 has no entry under this spelling.
Shades of meaning
Fernald has no entry of its own for set out; he lists it under plant.
Where he writes about it:
We set or set out slips, cuttings, young trees, etc., tho we may also be said to plant them; we plant corn, potatoes, etc., which we put in definite places, as in hills, with some care; we sow wheat or other small grains and seeds which are scattered in the process. — from plant