The Dune and Bulb Region stretches from the area around the lower reaches of the Old Rhine west of Leiden to just south of Haarlem. Since it is not a municipality or administrative region, the region's borders are not clearly defined. The Dune and Bulb Region proper is made up of the towns from Katwijk to Hillegom, and from the coast to the Kaag Lakes. Officials consider six municipalities to be part of this region: Hillegom, Katwijk, Lisse, Noordwijk, Noordwijkerhout and Teylingen. However, towns just outside these boundaries also consider themselves to be part of this region. Most of the towns in this area are in an administrative region called "Holland Rijnland", a regional collaboration (samenwerkingsverband) consisting of various municipalities in the Duin- en Bollenstreek and the Leiden area.
This area is the southern part of a larger flower-growing area called the Bulb Region (Bollenstreek). However, it is not unusual for the Dune and Bulb Region itself to be referred to as the Bulb Region.
The region is characterised by wide sandy ridges of flat land (cleared from dunes from 1650 to 1955 for agricultural use and human habitation), sandy soil between the dunes and polders (geestgrond), bulb fields and pasture land (weiland), all of which is protected from the North Sea by an extensive dune area.
The climate and soil of the region are excellent for bulb cultivation. Proximity to the sea results in a substantial amount of rain.
The mild autumn and winter, the cool but sunny spring and the drier summer ensures a growing season lasting from the early spring to the late autumn.