The Keukenhof bulb gardens near Lisse open to the public on Thursday for the 75th jubilee edition of the hugely popular tourist attraction.

The gardens at the Keukenhof attract some 1.5 million visitors a year during its brief, eight-week displays of blooming lilies, tulips, hyacinths, daffodils and crocuses.

In total, some seven million bulbs went into the ground last October for this year’s spring show, which will run until May 12.

The Keukenhof first opened its doors in 1949 when bulb growers and exporters came together discuss a way to showcase their wares. The first Keukenhof show, in 1950, was an immediate hit, with some 236,000 visitors. The number of participating growers has gone up tenfold to 100 since then.

“It’s going to be a festive year,” Keukenhof director Sandra Bechtholt told the Leidsch Dagblad at the official opening on Tuesday. “We will be telling the story of the spring flowering bulbs and how important they are for the Netherlands and the rest of the world.”

However, according to environmental action group Pesticide Action Network (PAN-NL) , 75 years of bulb growing has destroyed biodiversity and its use of pesticides is a threat to human health.

The group is calling on the Keukenhof to “get rid of a nasty heritage” and plant organic bulbs only.

The bulb industry is one of the world’s heaviest users of pesticides, which have been linked to diseases like Parkinson’s.

In June last year a court in Assen ruled that a lily bulb grower must stop using pesticides because they may be causing neurological diseases, but the case was later overturned on appeal.

Last year, European research led by Wageningen University showed that 42% of Dutch farmland has excessive levels of nitrogen and phosphates, in addition to widespread contamination with pesticide compounds.