Owner Philip Oostenrbrink said the thieves have left him no plants and no opportunity to buy stock.
The first raid last year saw stock worth £10,000 taken.
Plants worth £1,000 were taken in the second incident at the end of April.
The large volume of stock taken last summer would have required a lorry, according to Oostenrbink.
He added: "It was my dream to move from the Netherlands to England and start a nursery here, but with these horrible people just taking whatever they can find, it has been made impossible."
A police statement said the plants and shrubs had disappeared some time between Friday and Monday (23-26).
It added: "Anyone who witnessed the removal of plants or who has been offered them for sale is asked to contact 0845 60 70 999 quoting serial 1659 of 26/04."
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