A spirit seed is a rare seed that members can use to grow a spirit tree at level 83 Farming. Although the assist system can not be used at any point to help others grow spirit seeds, boosts can be used, allowing players to grow the tree as early as level 78 with a pork pie.
There are three spirit tree patches, one each at Port Sarim, Etceteria, and Brimhaven. However, only one spirit tree patch may initially be planted at one time. After completion of the quest Prisoner of Glouphrie, players may plant and grow up to two spirit trees with level 86 Farming (81 with pork pie, 82 with stranger plant boost, or 83 with garden pie). After completion of both Plague's End and Prisoner of Glouphrie, with level 89 farming (cannot be boosted), players can unlock a third spirit tree by talking to Glouron inside the Crwys Clan district of Prifddinas. Players must pay each farmer separately to watch it if planting two or three spirit trees. Multiple spirit tree seeds may be planted in plant pots and grown into spirit tree saplings at the same time, but the number that can be planted from a sapling into a patch is limited to the number of patches that are unlocked by the player. Once the spirit tree is grown or dies, it can be removed and another sapling planted.
Players can buy a spirit seed from Mrs. Winkin for 55,000 Vinesweeper points. Growing a spirit tree yields only 19,501.3 Farming experience, so players desiring experience would do better to trade Vinesweeper points for 55,000 Farming experience instead.