A prickly pear seed is a Farming seed from which prickly pears can be grown by players with 76 Farming. It is planted in the cactus patch in Al Kharid. Harvesting the grown plant gives Defence experience instead of a crop item.
It can be protected by paying a farmer 15 jangerberries, although this is unnecessary if the player has completed the hard Desert Tasks.
The seed can be found by pickpocketing from gnomes at level 75, from elves at level 85 or from dwarves at 90. They can also be gained through hunting in the Herblore Habitat, purchased for 3,000 points per seed at Vinesweeper or purchased for 15,000 glory per seed at the Mobilising Armiesminigame.