Gen 1: 11 says:
11 Then God said, “Let the earth sprout [j]vegetation, [k]plants yielding seed, and fruit trees on the earth bearing fruit according to [l]their kind [m]with seed in them”; and it was so. 12 The earth produced [n]vegetation, [o]plants yielding seed according to [p]their kind, and trees bearing fruit [q]with seed in them, according to [r]their kind; and God saw that it was good. 13 And there was evening and there was morning, a third day. (nasb)
Then, in Gen 1:16:
16 God made the two great lights, the greater light [x]to govern the day, and the lesser light [y]to govern the night; He made the stars also. 17 God placed them in the [z]expanse of the heavens to give light on the earth, 18 and [aa]to govern the day and the night, and to separate the light from the darkness; and God saw that it was good. 19 And there was evening and there was morning, a fourth day. (nasb)
So, according to Genesis, vegetation was created and grew, even produced fruit, for untold eons, before the Sun, or Moon were created.
Its quite amusing to read the mental gymnastics apologists put forward to explain these verses. Everything from light being emitted from black holes, to light being diffused by the good old water vapour canopy. However, the bible verses cant be any clearer to an average person reading them. There are a lot of quotes from JWorg about the accuracy of the bible but here are a couple worth considering:
"ALTHOUGH the Bible is not a science textbook, it is accurate when it discusses the natural world." - IS THE BIBLE REALLY FROM GOD?
Logical conclusion drawn from that statement; we accept the bible as it is written, there is no need to interpret any verses.
Concerning these verses JWorg says:
Myth: The Bible says that vegetation was created before the sun existed to support photosynthesis.—Genesis 1:11, 16.
Fact: The Bible shows that the sun, one of the stars that make up “the heavens,” was created before vegetation. (Genesis 1:1) Diffused light from the sun reached the earth’s surface during the first “day,” or epoch, of creation. As the atmosphere cleared, by the third “day” of creation, the light was strong enough to support photosynthesis. (Genesis 1:3-5, 12, 13) Only later did the sun become distinctly visible from the surface of the earth.—Genesis 1:16. - Does Science Agree With the Bible?
The JW answer is, as usual, misleading and disagrees with the bible account. The bible does not say that the sun was created along with 'the heavens'. It is very clear, the sun and the moon were created on the 4th day, after vegetation. If the first few verses of Genesis are read literally, then 'the heavens' do not include the sun, stars, or the moon.
This all ends in a paradox, either the bible is wrong, or the jw's are wrong. The bible, according to jw's, can't be wrong, but they feel the need to correct the bible account in this instance- even though, according to them, its right.