Old School RuneScape Wiki

Seaweed spore detail.png

Seaweed spores are used in the Farming skill and require level 23 in the skill to grow them. They are planted at the seaweed patch in the underwater area of Fossil Island. Players can pay Mernia to protect this patch by giving her 200 numulites.

The Giant Seaweed patch minimum harvest is unaffected by compost unlike herbs, but final yield is still increased on average.[1] However, magic secateurs and the farming cape do not have an effect.[2]

Once fully grown, which takes approximately 35-40 minutes, players will be able to harvest giant seaweeds. A minimum of three can be collected per patch, with the average being around 20–40 depending on one's Farming level if super or ultracompost is used.


Seaweed spores can be obtained via the following methods:

Farming info

Seaweed spore
Farming level 23
Patch Seaweed
Seeds per 1 seed
Payment 200 Numulites
Time 40 min (4x10 min)
Crop Giant seaweed
Planting 19
Harvesting 21

Dropping monsters

Monster Combat level Quantity Rarity
Lobstrosity 68 1–5 3; Uncommon
Long-tailed Wyvern 152 3–12 3; Uncommon
Spitting Wyvern 139 12 3; Uncommon
Taloned Wyvern 147 6–12 3; Uncommon
Ancient Wyvern 210 3–24 3; Uncommon
Ammonite Crab 25 1–2 4; Rare



  1. Jagex. Mod Ash's Twitter account. 4 Jun 2018. Mod Ash: "Yup, same as other patches with randomised yields that scale on your Farming level."
  2. Jagex. Mod Ash's Twitter account. 25 Jun 2018. Mod Ash: "No, doesn't look like it. I guess you weren't expected to have them equipped down there."