Buy RS3 Toadflax seed
The Toadflax seed is a members only Farming item in RuneScape 3. Plant one seed in a herb patch to grow grimy toadflax. You need level 38 Farming to plant it.
Each seed gives 34 Farming experience when planted. The crop takes 80 minutes to grow, in 4 stages of 20 minutes each. When you harvest, you get 38.5 experience per herb. Each planting has at least 3 harvest lives. Better compost and the crop farmer or master farmer outfits can give you more herbs from one seed. A nearby gardener will not watch over this herb, so it can get sick while it grows.
Toadflax seeds drop from many monsters. Common drops come from Dagannoths, Cave horrors, Turoths, Aberrant spectres, and Tree spirits. You can also pickpocket Master Farmers for a chance at one, or get them from Managing Miscellania when your workers are set to Farming.
The seed is tradeable and stackable, so it takes up little bank space. It can also be disassembled for Organic parts and a small chance at Living components. This seed is a solid pick for training Farming past level 38.