The previous answer gives you a graphic showing crops and how high they grow. Refer back to the final page at the end of the introduction. It shows the beans circled, with a reference number next to it. Look this reference number up on the graphic and you can tell you need to find the beans which are stacked two stacks high. But which are beans?

The answer to Puzzle 21, before this one, tells you that there are five bean plants in this greenhouse. Which type of plant appears 5 times? That must be the beans!

The one we're after is the only one that's two stacks high. That still doesn't give the map coordinates though.

We're in Greenhouse 6. Page 51 tells you where on the map this is. You can locate where you are in this room by logical deduction. You can't see a door so you must be stood in front of it.

Using the map at the start of Sector 3 we can see this room is 4 squares wide and three squares long. The picture shows 3 rows long by 4 rows wide of plants. We need to put one plot of plants in to each cell of the room. The one we want is 3 rows long back, and 3 rows wide back.