Keukenhof is a flower garden full of tulips and other spring flowers. It 35 km south of Amsterdam near the town of Lisse.
Opening days vary, depending on when it is Easter but usual from mid-March to the end of May. Opening time in 2008 is 20 March – 18 May, from 08.00 to 19.30
If you don't have your own transport you can take public transport.
From Leiden train station take bus 54
From Haarlem train station take bus 50 or 51 to Lisse, from here the shuttle bus.
From Schiphol take bus 58
Try to be as early as possible buses and also the park itself is very crowded, and especially so ar weekends and om easter Sunday and Monday. I would strongly advise you to buy tickets online to avoid queueing.
It is difficult to predict when the park is at its best because it all depends on the weather, even on a rainy day keukenhof is worth a visit. The bonus is that there are fewer people. Crocuses, narcissus and hyacinths are the first to flower followed by tulips.