Answer: So the correct answer would be 256 bulbs.
Explanation:
Well, it sounds like Geoff has quite the green thumb! It's great to see his garden growing so well. Well anyway based on the pattern of bulb production you mentioned, where the number of bulbs doubles each year, Geoff should expect 64 bulbs in the fourth year, 128 bulbs in the fifth year, and 256 bulbs in the sixth year. Hope you do good on the rest!