Buy RS3 Watermelon seed
The watermelon seed is a members-only Farming seed in RuneScape 3. You need level 47 Farming to plant it. Each allotment patch takes 3 seeds. When the crop is fully grown, you can harvest between 3 and 69 watermelons per patch. Any tier of the Greenfingers aura can raise that number even more.
Planting gives 48.5 Farming XP, and each watermelon you pick gives 54.5 XP. That makes this seed a solid pick for training Farming. Watermelons start with 3 harvest lives. Each tier of compost adds one more life, up to 6 with ultracompost. A higher Farming level also gives you a better chance to keep a harvest life while picking.
You can protect your crop in two ways. A nearby gardener will watch the patch for 10 curry leaves, noted or un-noted. You can also grow nasturtiums, white lilies, or starbloom flowers in a nearby flower patch to stop disease.
Watermelon seeds are tradeable and stackable, so they are easy to store and use in bulk. They can also be disassembled, giving mostly organic parts with a rare chance of living components.