Genesis 1:9-13 meaning

During the second day of creation, we saw a vertical division with God dividing the earth from the heavens. Now, we have a horizontal division with God dividing the dry land and seas. God is further establishing control over the chaos in verse 2. He is forming order from disorder and form from formlessness. God names the dry land earth. The gathering of the waters, He called seas.

God said, "Let the earth sprout vegetation" (v 11). God was providing for the future of mankind by making crops that reproduce. The seed-bearing plants and fruit trees represent plants designated for human consumption. Then God said, "Behold, I have given you every plant yielding seed that is on the surface of all the earth, and every tree which has fruit yielding seed; it shall be food for you" (Genesis 1:29). 

It is said in verses 11-12 that these plants shall reproduce according to their kind, which restated in James, "Can a fig tree, my brethren, produce olives, or a vine produce figs? Nor can salt water produce fresh" (James 3:12). Plants will only reproduce according to their kind, this is similar to the principle of sowing as we reap, which is explained in Galatians, "Do not be deceived, God is not mocked; for whatever a man sows, this he will also reap. For the one who sows to his own flesh will from the flesh reap corruption, but the one who sows to the Spirit will from the Spirit reap eternal life" (Galatians 6:7-8).

Those who live only to satisfy their own sinful nature will harvest decay and death from that sinful nature. But those who are obedient to God will reap life and blessings.