Jamieson, Fausset and Brown on Mark 4:7

7. And some fell among thorns, and the thorns grew up, and choked it, and it yielded no fruit--This case is that of ground not thoroughly cleaned of the thistles, &c.; which, rising above the good seed, "choke" or "smother" it, excluding light and air, and drawing away the moisture and richness of the soil. Hence it "becomes unfruitful" (Mt 13:22); it grows, but its growth is checked, and it never ripens. The evil here is neither a hard nor a shallow soil--there is softness enough, and depth enough; but it is the existence in it of what draws all the moisture and richness of the soil away to itself, and so starves the plant. What now are these "thorns?" See on Mr 4:19.

Fourth Case: The Good Ground. (Mr 4:8, 20).