Mark 4: 30-34: Mark shares one more Kingdom example from the teachings of Jesus on the subject, this time Jesus makes the comparison between the Kingdom and a mustard seed. This isn’t a long discussion, it’s very brief and to the point. The mustard seed is very small, apparently the smallest of garden seeds, and yet it can grow into a very large shrub up to six feet tall.1 One commentary says that it has been observed in Northern Lebanon to grow to the height of a rider on horseback in the wild.2 The Greek philosopher Pliny the Elder said that it is an invasive plant that can rarely be eradicated once it has been on the land.3
Jesus knew that His teaching on the kingdom of God was only a small start to the establishment of the Church. He was teaching these truths in the district of Galilee far away from the large cities and cultural hot spots of the day. This is where He wanted to plant the seeds of the Kingdom that would bring transformation not only to Galilee but to the whole world. God’s Kingdom would take root and produce something far greater than what it seemed to be at the time.
We can link this parable back to the others that He’s spoken in Mark 4 on the topic of the sower, the seeds and the soil. Just like in the other parables this little seed needs to be spread by a sower on good soil in order for it to produce a crop that far out weighs the number of grains cast upon the ground.
The spiritual lessons for us is that we shouldn’t look down upon the smallness of the seed that we are planting. When that seed contains the DNA of the Kingdom of God it will produce something far greater than what we would assume. The DNA of the Kingdom, things like prayer, faith, love and the message of the cross, if present will produce a result. Like the other parables though it must be sown into fertile soil.
Therefore it is our task to faithfully sow the message of the Gospel of the Kingdom of God and allow the message to produce its fruit. Being faithful is our task, the remainder of the task is found in the DNA of the seed.

1http://bible.faithlife.com/books/esv/Mk4.32
2http://www.ccel.org/ccel/smith_w/bibledict.html?term=Mustard
3http://en.wikipedia.org/wiki/Parable_of_the_Mustard_Seed