The Berberis Dell lies north of the Flag pole and was created from a gravel pit between 1869 to 1875. This dell, which was also known as the Flagstaff Dell, is the third largest man-made excavation at Kew after the Lake and the Rhododendron Dell.
The secluded character of this part of the gardens, together with the large collections of plants from the genus Berberis (barberry) make this feature worth visiting. Most of the Berberis species are easily grown in most soils and are fully hardy in the United Kingdom. Of the total 500 species, 200 are from China and only two are from Europe. The European barberry (Berberis vulgaris) can be found near the path between the Victoria Gate and the Flagstaff.
The two largest, 31-year-old plants of Berberis lycoides are about 5m tall and 8m wide, and can be found towards the centre of the Berberis Dell .They flower between April and May with large yellow flower clusters. The majority of the barberries possess spines and evergreen leaves. From early spring to summer there are always plants in flower, in shades of yellow or orange, and in summer and autumn the fruit have red, black or blue colouration.
The other large genus of the barberry family (Berberidaceae) which is also located here is the Mahonia, a genus with many garden-worthy species and cultivars. Amongst the most useful shrubby species is the Mahonia x media which was produced from an accidental cross between Mahonia japonica and Mahonia lomariifolia. The result was this magnificent hybrid which gave rise to several garden selections. Most of the beds in this area are shaded over by lime trees (Tilia species), which belong to the collection of limes to the west of the Dell. There are many tree species scattered around the Dell, for example Magnolia species such as the evergreen Magnolia grandiflora. The young katsura tree (Cercidiphyllum japonicum) on the lawn in the middle of the Dell represents the tallest deciduous tree species in Japan. It is situated in the Dell where there was once a small pond. There are also Liquidambar species (Altingiaceae) such as Liquidambar styraciflua (America) and Liquidambar formosana (China, Taiwan), which make wonderful garden and park trees, especially in autumn when their leaves turn from red and orange to yellow. Liquidambar orientalis is a rare tree which occurs only in southern Turkey, and yields valuable timber and aromatic balsams. Towards the Flag pole are species of climbers from the genus Actinidia, the best known being Actinidia sinensis which yields kiwi fruits.
In the past, Berberis was used for wood-turning, dyes, staining wood and French jam, as well as for medicinal uses.
Next to the Berberis Dell, oppposite the Flag pole, is a very interesting collection of camellias. The Camellia bed stretches along the wall adjoining Kew Road and contains many mature specimens which flower from late March to the beginning of May.
The Berberis Dell is number 6 on the Visitor Map.