If you're a bit confused as to why the prices on the website look different to the catalogue or advert, that's because your catalogue and advert are offering a reduced price. All you have to do is to add the plant to the order and then enter the offer code in the 'offer code' box in the basket. The prices will then magically reduce to the ones you expected to see. 

The catalogue code is on the front of the catalogue, or on the letter and order form that came with it.