Grassidium

Plants spread to nearby blocks depending on light, and by default they do it faster in the rain (land plants only). Small plants like grass, ferns and seagrass can grow into their tall versions, and sea pickles multiply in place. It works underwater too: seagrass, kelp and corals spread on their own.

If too many plants of the same kind are packed together, they stop spreading. Solid blocks stop spreading completely. Fences, iron bars and glass lower the chance by default, and how much is set in the rules below (at 100 they block it fully).

Modded plants work automatically if they use the vanilla plant block tags.

Settings

No config file, everything is a gamerule, so it’s per-world. Set it in World Creation → Game Rules (World Updates) or in-game with /gamerule.

| Rule (1.21.1) | Rule (1.21.11+) | Default | What it does |
|:—|:—|:—:|:—|
| doPlantSpread | do_plant_spread | true | Turns all spreading and growth on/off |
| plantSpreadChance | plant_spread_chance | 3 | Spread chance for regular plants, % |
| flowerSpreadChance | flower_spread_chance | 1 | Spread chance for flowers, % |
| plantGrowthChance | plant_growth_chance | 1 | Chance for small plants to grow tall, % |
| plantSpreadRadius | plant_spread_radius | 3 | Max spread distance in blocks (1-8) |
| plantRainMultiplier | plant_rain_multiplier | 150 | Growth speed in rain, % (150 = 1.5x) |
| plantObstaclePenalty | plant_obstacle_penalty | 50 | Spread penalty through fences/glass, % (100 = fully blocked) |