diff --git a/src/commands/apply-terrain-brush-patch-command.ts b/src/commands/apply-terrain-brush-patch-command.ts
index 8b6d6c3a..ce59ebf7 100644
--- a/src/commands/apply-terrain-brush-patch-command.ts
+++ b/src/commands/apply-terrain-brush-patch-command.ts
@@ -51,7 +51,8 @@ export function isTerrainBrushPatchEmpty(patch: TerrainBrushPatch): boolean {
   return (
     patch.heightSamples.length === 0 &&
     patch.paintWeights.length === 0 &&
-    patch.foliageMaskValues.length === 0
+    patch.foliageMaskValues.length === 0 &&
+    patch.foliageBlockerMaskValues.length === 0
   );
 }
 
@@ -89,7 +90,10 @@ export function createApplyTerrainBrushPatchCommand(
     paintWeights: options.patch.paintWeights.map((entry) => ({ ...entry })),
     foliageMaskValues: options.patch.foliageMaskValues.map((entry) => ({
       ...entry
-    }))
+    })),
+    foliageBlockerMaskValues: options.patch.foliageBlockerMaskValues.map(
+      (entry) => ({ ...entry })
+    )
   };
   let previousSelection: EditorSelection | null = null;
   let previousToolMode: ToolMode | null = null;
@@ -167,6 +171,21 @@ export function createApplyTerrainBrushPatchCommand(
       }
     }
 
+    for (const entry of patch.foliageBlockerMaskValues) {
+      assertValidPatchEntry(
+        entry,
+        terrain.foliageBlockerMask.values.length,
+        "Terrain foliage blocker mask"
+      );
+      terrain.foliageBlockerMask.values[entry.index] =
+        direction === "forward" ? entry.after : entry.before;
+      renderDirtyBounds = mergeTerrainSampleIndexIntoBounds(
+        renderDirtyBounds,
+        terrain,
+        entry.index
+      );
+    }
+
     markTerrainRenderSamplesDirty(terrain, renderDirtyBounds);
 
     context.setDocument({
diff --git a/src/core/terrain-brush.ts b/src/core/terrain-brush.ts
index 49459bac..814d31a5 100644
--- a/src/core/terrain-brush.ts
+++ b/src/core/terrain-brush.ts
@@ -7,7 +7,9 @@ export type TerrainBrushTool =
   | "flatten"
   | "paint"
   | "foliagePaint"
-  | "foliageErase";
+  | "foliageErase"
+  | "foliageBlockerPaint"
+  | "foliageBlockerErase";
 
 export interface TerrainBrushSettings {
   radius: number;
@@ -17,7 +19,10 @@ export interface TerrainBrushSettings {
 
 export interface ArmedTerrainSculptBrushState extends TerrainBrushSettings {
   terrainId: string;
-  tool: Exclude<TerrainBrushTool, "paint" | "foliagePaint" | "foliageErase">;
+  tool: Exclude<
+    TerrainBrushTool,
+    "paint" | "foliagePaint" | "foliageErase" | "foliageBlockerPaint" | "foliageBlockerErase"
+  >;
 }
 
 export interface ArmedTerrainPaintBrushState extends TerrainBrushSettings {
@@ -33,10 +38,17 @@ export interface ArmedTerrainFoliagePaintBrushState
   foliageLayerId: string;
 }
 
+export interface ArmedTerrainFoliageBlockerBrushState
+  extends TerrainBrushSettings {
+  terrainId: string;
+  tool: "foliageBlockerPaint" | "foliageBlockerErase";
+}
+
 export type ArmedTerrainBrushState =
   | ArmedTerrainSculptBrushState
   | ArmedTerrainPaintBrushState
-  | ArmedTerrainFoliagePaintBrushState;
+  | ArmedTerrainFoliagePaintBrushState
+  | ArmedTerrainFoliageBlockerBrushState;
 
 export interface TerrainSampleValuePatch {
   index: number;
@@ -53,6 +65,7 @@ export interface TerrainBrushPatch {
   heightSamples: TerrainSampleValuePatch[];
   paintWeights: TerrainSampleValuePatch[];
   foliageMaskValues: TerrainFoliageMaskValuePatch[];
+  foliageBlockerMaskValues: TerrainSampleValuePatch[];
 }
 
 export interface TerrainBrushStrokeCommit {
@@ -143,6 +156,10 @@ export function getTerrainBrushToolLabel(tool: TerrainBrushTool): string {
       return "Paint Foliage";
     case "foliageErase":
       return "Erase Foliage";
+    case "foliageBlockerPaint":
+      return "Paint Foliage Blocker";
+    case "foliageBlockerErase":
+      return "Clear Foliage Blocker";
   }
 }
 
diff --git a/src/document/migrate-scene-document.ts b/src/document/migrate-scene-document.ts
index 1e7a850f..a010ab08 100644
--- a/src/document/migrate-scene-document.ts
+++ b/src/document/migrate-scene-document.ts
@@ -2320,6 +2320,38 @@ function readTerrain(value: unknown, label: string): Terrain {
             })
           );
         })();
+  const foliageBlockerMask =
+    value.foliageBlockerMask === undefined
+      ? undefined
+      : (() => {
+          if (!isRecord(value.foliageBlockerMask)) {
+            throw new Error(`${label}.foliageBlockerMask must be an object.`);
+          }
+
+          if (!Array.isArray(value.foliageBlockerMask.values)) {
+            throw new Error(
+              `${label}.foliageBlockerMask.values must be an array.`
+            );
+          }
+
+          return {
+            resolutionX: expectFiniteNumber(
+              value.foliageBlockerMask.resolutionX,
+              `${label}.foliageBlockerMask.resolutionX`
+            ),
+            resolutionZ: expectFiniteNumber(
+              value.foliageBlockerMask.resolutionZ,
+              `${label}.foliageBlockerMask.resolutionZ`
+            ),
+            values: value.foliageBlockerMask.values.map(
+              (maskSample, sampleIndex) =>
+                expectFiniteNumber(
+                  maskSample,
+                  `${label}.foliageBlockerMask.values.${sampleIndex}`
+                )
+            )
+          };
+        })();
 
   return createTerrain({
     id: expectString(value.id, `${label}.id`),
@@ -2339,7 +2371,8 @@ function readTerrain(value: unknown, label: string): Terrain {
     heights,
     layers,
     paintWeights,
-    foliageMasks
+    foliageMasks,
+    foliageBlockerMask
   });
 }
 
diff --git a/src/document/scene-document.ts b/src/document/scene-document.ts
index 04b38c56..f067d030 100644
--- a/src/document/scene-document.ts
+++ b/src/document/scene-document.ts
@@ -35,7 +35,8 @@ import {
   type FoliagePrototypeRegistry
 } from "../foliage/foliage";
 
-export const SCENE_DOCUMENT_VERSION = 94 as const;
+export const SCENE_DOCUMENT_VERSION = 95 as const;
+export const FOLIAGE_BLOCKER_MASKS_SCENE_DOCUMENT_VERSION = 95 as const;
 export const FOLIAGE_QUALITY_SCENE_DOCUMENT_VERSION = 94 as const;
 export const FOLIAGE_MASKS_SCENE_DOCUMENT_VERSION = 93 as const;
 export const FOLIAGE_FOUNDATION_SCENE_DOCUMENT_VERSION = 92 as const;
diff --git a/src/geometry/terrain-brush.ts b/src/geometry/terrain-brush.ts
index 6cf60340..f73af89c 100644
--- a/src/geometry/terrain-brush.ts
+++ b/src/geometry/terrain-brush.ts
@@ -7,6 +7,7 @@ import type {
 } from "../core/terrain-brush";
 import {
   createTerrain,
+  getTerrainFoliageBlockerMaskValueAtSample,
   getOrCreateTerrainFoliageMask,
   getTerrainHeightAtSample,
   getTerrainFoliageMask,
@@ -36,6 +37,7 @@ export interface TerrainBrushStampMutationResult {
   heightSampleIndices: number[];
   paintWeightIndices: number[];
   foliageMaskValueIndices: TerrainFoliageMaskValueIndex[];
+  foliageBlockerMaskValueIndices: number[];
 }
 
 export interface TerrainFoliageMaskValueIndex {
@@ -337,7 +339,8 @@ export function applyTerrainBrushStampInPlace(options: {
       dirtyBounds: null,
       heightSampleIndices: [],
       paintWeightIndices: [],
-      foliageMaskValueIndices: []
+      foliageMaskValueIndices: [],
+      foliageBlockerMaskValueIndices: []
     };
   }
 
@@ -356,6 +359,7 @@ export function applyTerrainBrushStampInPlace(options: {
   const heightSampleIndices: number[] = [];
   const paintWeightIndices: number[] = [];
   const foliageMaskValueIndices: TerrainFoliageMaskValueIndex[] = [];
+  const foliageBlockerMaskValueIndices: number[] = [];
 
   const markDirty = (sampleX: number, sampleZ: number) => {
     if (dirtyBounds === null) {
@@ -494,6 +498,29 @@ export function applyTerrainBrushStampInPlace(options: {
           }
           continue;
         }
+        case "foliageBlockerPaint":
+        case "foliageBlockerErase": {
+          const maskIndex = getTerrainFoliageMaskSampleIndex(
+            terrain.foliageBlockerMask,
+            sampleX,
+            sampleZ
+          );
+          const currentMaskValue =
+            terrain.foliageBlockerMask.values[maskIndex] ?? 0;
+          const targetMaskValue = tool === "foliageBlockerPaint" ? 1 : 0;
+          const nextMaskValue = lerp(
+            currentMaskValue,
+            targetMaskValue,
+            clamp01(smoothingStrength * weight)
+          );
+
+          if (nextMaskValue !== currentMaskValue) {
+            terrain.foliageBlockerMask.values[maskIndex] = nextMaskValue;
+            foliageBlockerMaskValueIndices.push(maskIndex);
+            markDirty(sampleX, sampleZ);
+          }
+          continue;
+        }
       }
 
       if (nextHeight !== currentHeight) {
@@ -509,7 +536,8 @@ export function applyTerrainBrushStampInPlace(options: {
     dirtyBounds,
     heightSampleIndices,
     paintWeightIndices,
-    foliageMaskValueIndices
+    foliageMaskValueIndices,
+    foliageBlockerMaskValueIndices
   };
 }
 
@@ -519,6 +547,7 @@ export function createTerrainBrushPatchFromTerrains(options: {
   heightSampleIndices: Iterable<number>;
   paintWeightIndices: Iterable<number>;
   foliageMaskValueIndices?: Iterable<TerrainFoliageMaskValueIndex>;
+  foliageBlockerMaskValueIndices?: Iterable<number>;
 }): TerrainBrushPatch {
   const { before, after } = options;
 
@@ -530,7 +559,9 @@ export function createTerrainBrushPatchFromTerrains(options: {
     before.sampleCountX !== after.sampleCountX ||
     before.sampleCountZ !== after.sampleCountZ ||
     before.heights.length !== after.heights.length ||
-    before.paintWeights.length !== after.paintWeights.length
+    before.paintWeights.length !== after.paintWeights.length ||
+    before.foliageBlockerMask.values.length !==
+      after.foliageBlockerMask.values.length
   ) {
     throw new Error(
       "Terrain brush patches require matching terrain sample dimensions."
@@ -540,6 +571,8 @@ export function createTerrainBrushPatchFromTerrains(options: {
   const heightSamples: TerrainBrushPatch["heightSamples"] = [];
   const paintWeights: TerrainBrushPatch["paintWeights"] = [];
   const foliageMaskValues: TerrainBrushPatch["foliageMaskValues"] = [];
+  const foliageBlockerMaskValues: TerrainBrushPatch["foliageBlockerMaskValues"] =
+    [];
   const normalizeIndices = (
     indices: Iterable<number>,
     length: number,
@@ -641,11 +674,41 @@ export function createTerrainBrushPatchFromTerrains(options: {
       left.layerId.localeCompare(right.layerId) || left.index - right.index
   );
 
+  for (const maskIndex of normalizeIndices(
+    options.foliageBlockerMaskValueIndices ?? [],
+    before.foliageBlockerMask.values.length,
+    "Terrain foliage blocker mask"
+  )) {
+    const beforeValue =
+      getTerrainFoliageBlockerMaskValueAtSample(
+        before.foliageBlockerMask,
+        maskIndex % before.foliageBlockerMask.resolutionX,
+        Math.floor(maskIndex / before.foliageBlockerMask.resolutionX)
+      ) ?? 0;
+    const afterValue =
+      getTerrainFoliageBlockerMaskValueAtSample(
+        after.foliageBlockerMask,
+        maskIndex % after.foliageBlockerMask.resolutionX,
+        Math.floor(maskIndex / after.foliageBlockerMask.resolutionX)
+      ) ?? 0;
+
+    if (beforeValue === afterValue) {
+      continue;
+    }
+
+    foliageBlockerMaskValues.push({
+      index: maskIndex,
+      before: beforeValue,
+      after: afterValue
+    });
+  }
+
   return {
     terrainId: before.id,
     heightSamples,
     paintWeights,
-    foliageMaskValues
+    foliageMaskValues,
+    foliageBlockerMaskValues
   };
 }
 
diff --git a/src/geometry/terrain-mesh.ts b/src/geometry/terrain-mesh.ts
index 72811b46..cda9b3b8 100644
--- a/src/geometry/terrain-mesh.ts
+++ b/src/geometry/terrain-mesh.ts
@@ -3,6 +3,7 @@ import { BufferAttribute, BufferGeometry } from "three";
 import type { Vec3 } from "../core/vector";
 import {
   getTerrainFoliageMask,
+  getTerrainFoliageBlockerMaskValueAtSample,
   getTerrainFoliageMaskValueAtSample,
   getTerrainHeightAtSample,
   getTerrainSampleLayerWeights,
@@ -47,6 +48,7 @@ const TERRAIN_LOD_HYSTERESIS_RATIO = 0.16;
 
 interface TerrainMeshBuildOptions {
   foliageMaskLayerId?: string | null;
+  foliageBlockerMask?: boolean;
 }
 
 export interface TerrainLodLevelMeshData {
@@ -225,13 +227,19 @@ export function buildTerrainDerivedMeshData(
       }
       layerWeightOffset += TERRAIN_LAYER_COUNT;
       foliageMaskWeights[foliageMaskWeightOffset] =
-        foliageMask === null
-          ? 0
-          : getTerrainFoliageMaskValueAtSample(
-              foliageMask,
+        options.foliageBlockerMask === true
+          ? getTerrainFoliageBlockerMaskValueAtSample(
+              terrain.foliageBlockerMask,
               sampleX,
               sampleZ
-            );
+            )
+          : foliageMask === null
+            ? 0
+            : getTerrainFoliageMaskValueAtSample(
+                foliageMask,
+                sampleX,
+                sampleZ
+              );
       foliageMaskWeightOffset += 1;
     }
   }
@@ -399,9 +407,15 @@ function pushTerrainLodVertex(
       ? null
       : getTerrainFoliageMask(terrain, options.foliageMaskLayerId);
   foliageMaskWeights.push(
-    foliageMask === null
-      ? 0
-      : getTerrainFoliageMaskValueAtSample(foliageMask, sampleX, sampleZ)
+    options.foliageBlockerMask === true
+      ? getTerrainFoliageBlockerMaskValueAtSample(
+          terrain.foliageBlockerMask,
+          sampleX,
+          sampleZ
+        )
+      : foliageMask === null
+        ? 0
+        : getTerrainFoliageMaskValueAtSample(foliageMask, sampleX, sampleZ)
   );
 }