Albert Barnes Commentary Matthew 13:5

"and others fell upon the rocky places, where they had not much earth: and straightway they sprang up, because they had no deepness of earth:" — Matthew 13:5 (ASV)

Stony places. This refers to ground where there was little earth and which was also hard and rocky. As a result, the roots could not strike down into the earth for sufficient moisture to support the plant. When the sun became hot, they of course withered away. They sprang up sooner because there was little earth to cover them.

Forthwith. This means immediately. It is not that they sprouted and grew any quicker or faster than the others, but rather that they did not take as long to reach the surface. Having little root, they soon withered away.