Botanic Garden, Oxford
Britain's oldest botanic garden with thousands of species of plants from all over the world. A lovely place to sit, or wander down the river. Situated on the site of the old Jewish cemetary.
Open: winter - daily 9am-4.30pm, summer - daily 9am-5pm (closed Good Fri & Christmas Day).
£ : yes though I can't remember how much
The University Botanical Garden is a lovely spot to get away from the hubbub of the tourist and student laden streets and is full of interesting plants collected for the university over the centuries. Last time I visited, the Century cactus was in flower, but you'll have to wait another hundred years (approximately) to see it again!
It is the oldest botanical garden in Britain, founded in 1621 and beautifully sited along the border of the River Cherwell (entrance just off the High Street, nearly opposite Magdalen college).
Open daily 09:00-16:30 (16:45 in summer) except Good Friday and Christmas day.
Glasshouses only open 14:00-16:00
Price £2 April-August, donations requested at other times.
(Picture not my own)