Seed could certainly germinate, because the ground would grow warm quickly with the heat of the sun. But there was no depth of earth and when a plant sent down its roots in search of nourishment and moisture, it would meet only the rock. It would swiftly starve, and shrivel and die. When the sower was sowing, the ground would look clean enough. It is easy to make a garden look clean by simply turning it over, but in the ground still lay the fibrous roots of the couch grass and the bishop weed and all the perennial pests, ready to spring to life again.
Every gardener knows that the weeds grow with a speed and strength that few good seeds can equal.
The result was that the good seed and the dormant weeds grew together, but the weeds were so strong that they throttled the life out of the seed. Finally, the good ground. Deep and clean and soft. The seed could gain an entry, find nourishment, and grow unchecked. In the good ground it brought forth an abundant harvest.