In nature a seed is planted so that something might grow. Notice I said might. Just because the seed is planted does not mean that thing will grow. There could be a myriad of reasons. The seed was to young to old, diseased, infertile, etc. However, the one who plants that seed will not know that until the seed is in the ground.
If the farmer was to afraid to plant his seeds in the springtime there would be no food to harvest. If we are too afraid to plant our spiritual seeds there will be no harvest. To add to that there will be spiritual starvation for lack of food.
In Galatians 6 : 9 we are told:
Galatians 6:9 English Standard Version (ESV)
9 And let us not grow weary of doing good, for in due season we will reap, if we do not give up.
We are promised that in due season we will reap a harvest if we do not give up.
In 2 Corinthians we are told ;
The point is this: whoever sows sparingly will also reap sparingly, and whoever sows bountifully will also reap bountifully.
Let us not grow weary of sowing the seeds, for even though not all of them will sprout, some will, and those will be the ones we tenderly care for so that the harvest will be rich.
Be willing to plant a seed, be willing to watch it wither, be willing to watch it grow. That is our mission. Be willing to produce a harvest.