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Tulips are spring flowers, the latest you can find them out in the countryside and gardens is May, depending on the weather it can be as early as early May.
You can see flower fields of other flowers, which from a distance look quite like tulip fields. These can be seen from the train line Leiden to Alkmaar, and more can be seen a little away from that railway line when you use a car or bicycle to cycle along the outside of the Dunes area.
And you might be able to find some (very few) tulips on the more touristy flower markets, like the one on Singel in Amsterdam.
Upvote:7
Tulip season runs from the end of March until mid May, with the blooms peaking in mid-April. By June, and especially by the end of the month, they are long gone. You might visit the Amsterdam Tulip Museum for a bit of the experience, or stop at tulip field in which, after the season, many other varieties are grown. Annemiekeβs Picking Garden in Hillegom (randomly google searched), is one such, convenient since it's near the Ford Museum and within walking distance from the Keukenhof Gardens.