The kingdom of God is like a man who casts seed upon the soil: and he goes to bed at night and gets up by day, and the seeds sprouts and grows--how, he himself does not know. The soil produces crops by itself; first the blade, then the head, then the mature grain in the head. Mark 4:26-28, NASB
The miracle of it all! One day you have dirt and a dead-looking little seed. A week later you have a growing plant!
We should see the parable of the growing seed as an extension of the parable of the sower (Matt. 13:3-8; Mark 4:1-20), especially the last part, which deals with the fruitfulness of good soil. All in all, the parable of the sower was rather discouraging, since it predominantly spoke of failure for the person sowing the gospel seed, with only one fourth of the hearers truly accepting the Word.
The parable of the growing seed is in one sense a correction provided by Jesus as an encouragement to those tempted to feel discouraged with the amount of fruitless labor they are expending on those with "hearing" problems. The bottom line in the parable of the growing seed is that things are happening, even when it doesn't look that way--that God is growing His kingdom in the hearts of people even as we sleep. It is a process that we don't understand, but one that is evident in germination and the developing fruit.
Ellen White sets forth that truth in a way that I have found encouraging throughout the years. Speaking of the resurrection day, she writes, "All the perplexities of life's experience will then be made plain. Where to us have appeared only confusion and disappointment, broken purposes and thwarted plans, will be seen a grand, overruling, victorious purpose, a divine harmony.
"There all who have wrought with unselfish spirit will behold the fruit of their labors....How little of the result of the world's noblest work is in this life manifest to the doer! How many toil unselfishly and unweariedly for those who pass beyond their reach and knowledge! Parents and teachers lie down in their last sleep, their lifework seeming to have been wrought in vain; they know not that their faithfulness has unsealed springs of blessing that can never cease to flow....Men sow the seed from which, above their graves, others reap blessed harvests....They are content here to know that they have set in motion agencies for good. In the hereafter the action and reaction of all these will be seen" (Education, p. 305).
The bottom line: don't be discouraged by what you see. The Holy Spirit is working in ways we do not understand.