"He's tethered in me pumpkin patch. Thought he oughta see the trees an' - an' smell fresh air - before - "
--Rubeus Hagrid while awaiting Buckbeak's executioner (PA16)
A small pumpkin patch is located behind Hagrid’s hut and enclosed by a fence. Hagrid grows magically large pumpkins in his pumpkin patch (CS7, PA21). Harry sees twelve enormous pumpkins there during his second year (CS7).
There is some conflation between the pumpkin patch and the vegetable patch, which are both behind Hagrid's hut. CS7 says the pumpkins are "in the small vegetable patch."