diff --git a/garden-service/src/garden.ts b/garden-service/src/garden.ts
index 51d5f3d77b..65c5505778 100644
--- a/garden-service/src/garden.ts
+++ b/garden-service/src/garden.ts
@@ -85,20 +85,22 @@ interface ModuleConfigResolveOpts extends ContextResolveOpts {
 }
 
 export interface GardenParams {
-  buildDir: BuildDir,
-  environmentName: string,
-  gardenDirPath: string,
-  opts: GardenOpts,
-  plugins: Plugins,
-  projectName: string,
-  projectRoot: string,
-  projectSources?: SourceConfig[],
-  providerConfigs: ProviderConfig[],
-  variables: PrimitiveMap,
-  workingCopyId: string,
+  buildDir: BuildDir
+  environmentName: string
   dotIgnoreFiles: string[]
+  gardenDirPath: string
+  log: LogEntry
   moduleIncludePatterns?: string[]
   moduleExcludePatterns?: string[]
+  opts: GardenOpts
+  plugins: Plugins
+  projectName: string
+  projectRoot: string
+  projectSources?: SourceConfig[]
+  providerConfigs: ProviderConfig[]
+  variables: PrimitiveMap
+  vcs: VcsHandler
+  workingCopyId: string
 }
 
 export class Garden {
@@ -139,6 +141,7 @@ export class Garden {
     this.buildDir = params.buildDir
     this.environmentName = params.environmentName
     this.gardenDirPath = params.gardenDirPath
+    this.log = params.log
     this.opts = params.opts
     this.projectName = params.projectName
     this.projectRoot = params.projectRoot
@@ -151,6 +154,7 @@ export class Garden {
     this.moduleExcludePatterns = params.moduleExcludePatterns || []
     this.asyncLock = new AsyncLock()
     this.persistent = !!params.opts.persistent
+    this.vcs = params.vcs
 
     // make sure we're on a supported platform
     const currentPlatform = platform()
@@ -165,9 +169,7 @@ export class Garden {
     }
 
     this.modulesScanned = false
-    this.log = this.opts.log || getLogger().placeholder()
     // TODO: Support other VCS options.
-    this.vcs = new GitHandler(this.gardenDirPath, this.dotIgnoreFiles)
     this.configStore = new LocalConfigStore(this.gardenDirPath)
     this.globalConfigStore = new GlobalConfigStore()
     this.cache = new TreeCache()
@@ -220,11 +222,16 @@ export class Garden {
     gardenDirPath = resolve(projectRoot, gardenDirPath || DEFAULT_GARDEN_DIR_NAME)
     const buildDir = await BuildDir.factory(projectRoot, gardenDirPath)
     const workingCopyId = await getWorkingCopyId(gardenDirPath)
+    const log = opts.log || getLogger().placeholder()
 
     // We always exclude the garden dir
     const gardenDirExcludePattern = `${relative(projectRoot, gardenDirPath)}/**/*`
     const moduleExcludePatterns = [...((config.modules || {}).exclude || []), gardenDirExcludePattern]
 
+    // Ensure the project root is in a git repo
+    const vcs = new GitHandler(gardenDirPath, config.dotIgnoreFiles)
+    await vcs.getRepoRoot(log, projectRoot)
+
     const garden = new this({
       projectRoot,
       projectName,
@@ -240,6 +247,8 @@ export class Garden {
       workingCopyId,
       dotIgnoreFiles: config.dotIgnoreFiles,
       moduleIncludePatterns: (config.modules || {}).include,
+      log,
+      vcs,
     }) as InstanceType<T>
 
     return garden
diff --git a/garden-service/src/vcs/git.ts b/garden-service/src/vcs/git.ts
index 30cb4b1948..677f87adc4 100644
--- a/garden-service/src/vcs/git.ts
+++ b/garden-service/src/vcs/git.ts
@@ -73,13 +73,32 @@ export class GitHandler extends VcsHandler {
     }
   }
 
+  async getRepoRoot(log: LogEntry, path: string) {
+    const git = this.gitCli(log, path)
+
+    try {
+      return (await git("rev-parse", "--show-toplevel"))[0]
+    } catch (err) {
+      if (err.exitCode === 128) {
+        // Throw nice error when we detect that we're not in a repo root
+        throw new RuntimeError(deline`
+          Path ${path} is not in a git repository root. Garden must be run from within a git repo.
+          Please run \`git init\` if you're starting a new project and repository, or move the project to an
+          existing repository, and try again.
+        `, { path })
+      } else {
+        throw err
+      }
+    }
+  }
+
   /**
    * Returns a list of files, along with file hashes, under the given path, taking into account the configured
    * .ignore files, and the specified include/exclude filters.
    */
   async getFiles({ log, path, include, exclude }: GetFilesParams): Promise<VcsFile[]> {
     const git = this.gitCli(log, path)
-    const gitRoot = (await git("rev-parse", "--show-toplevel"))[0]
+    const gitRoot = await this.getRepoRoot(log, path)
 
     // List modified files, so that we can ensure we have the right hash for them later
     const modified = new Set((await this.getModifiedFiles(git, path))
diff --git a/garden-service/src/vcs/vcs.ts b/garden-service/src/vcs/vcs.ts
index 9ca2ab974f..4100bfc114 100644
--- a/garden-service/src/vcs/vcs.ts
+++ b/garden-service/src/vcs/vcs.ts
@@ -88,6 +88,7 @@ export abstract class VcsHandler {
   constructor(protected gardenDirPath: string, protected ignoreFiles: string[]) { }
 
   abstract name: string
+  abstract async getRepoRoot(log: LogEntry, path: string): Promise<string>
   abstract async getFiles(params: GetFilesParams): Promise<VcsFile[]>
   abstract async ensureRemoteSource(params: RemoteSourceParams): Promise<string>
   abstract async updateRemoteSource(params: RemoteSourceParams): Promise<void>
diff --git a/garden-service/test/unit/src/garden.ts b/garden-service/test/unit/src/garden.ts
index 56bb6da049..37e9a6b74b 100644
--- a/garden-service/test/unit/src/garden.ts
+++ b/garden-service/test/unit/src/garden.ts
@@ -1,5 +1,6 @@
 import { expect } from "chai"
 import td from "testdouble"
+import tmp from "tmp-promise"
 import { join, resolve } from "path"
 import { Garden } from "../../../src/garden"
 import {
@@ -33,6 +34,8 @@ import { keyBy, set } from "lodash"
 import stripAnsi from "strip-ansi"
 import { joi } from "../../../src/config/common"
 import { defaultDotIgnoreFiles } from "../../../src/util/fs"
+import { realpath, writeFile } from "fs-extra"
+import { dedent } from "../../../src/util/string"
 
 describe("Garden", () => {
   beforeEach(async () => {
@@ -273,6 +276,21 @@ describe("Garden", () => {
         c: "c",
       })
     })
+
+    it("should throw if project root is not in a git repo root", async () => {
+      const tmpDir = await tmp.dir({ unsafeCleanup: true })
+
+      try {
+        const tmpPath = await realpath(tmpDir.path)
+        await writeFile(join(tmpPath, "garden.yml"), dedent`
+          kind: Project
+          name: foo
+        `)
+        await expectError(async () => Garden.factory(tmpPath, {}), "runtime")
+      } finally {
+        await tmpDir.cleanup()
+      }
+    })
   })
 
   describe("resolveProviders", () => {
diff --git a/garden-service/test/unit/src/vcs/git.ts b/garden-service/test/unit/src/vcs/git.ts
index b94d0db66a..1f724ab783 100644
--- a/garden-service/test/unit/src/vcs/git.ts
+++ b/garden-service/test/unit/src/vcs/git.ts
@@ -18,6 +18,7 @@ import { getCommitIdFromRefList, parseGitUrl, GitHandler } from "../../../../src
 import { fixedExcludes } from "../../../../src/util/fs"
 import { LogEntry } from "../../../../src/logger/log-entry"
 import { hashRepoUrl } from "../../../../src/util/ext-source-util"
+import { deline } from "../../../../src/util/string"
 
 // Overriding this to make sure any ignorefile name is respected
 const defaultIgnoreFilename = ".testignore"
@@ -56,7 +57,7 @@ async function addToIgnore(tmpPath: string, pathToExclude: string, ignoreFilenam
 describe("GitHandler", () => {
   let tmpDir: tmp.DirectoryResult
   let tmpPath: string
-  let git
+  let git: any
   let handler: GitHandler
   let log: LogEntry
 
@@ -74,6 +75,30 @@ describe("GitHandler", () => {
     await tmpDir.cleanup()
   })
 
+  describe("getRepoRoot", () => {
+    it("should return the repo root if it is the same as the given path", async () => {
+      const path = tmpPath
+      expect(await handler.getRepoRoot(log, path)).to.equal(tmpPath)
+    })
+
+    it("should return the nearest repo root, given a subpath of that repo", async () => {
+      const dirPath = join(tmpPath, "dir")
+      await mkdir(dirPath)
+      expect(await handler.getRepoRoot(log, dirPath)).to.equal(tmpPath)
+    })
+
+    it("should throw a nice error when given a path outside of a repo", async () => {
+      await expectError(
+        () => handler.getRepoRoot(log, "/tmp"),
+        (err) => expect(err.message).to.equal(deline`
+          Path /tmp is not in a git repository root. Garden must be run from within a git repo.
+          Please run \`git init\` if you're starting a new project and repository, or move the project to
+          an existing repository, and try again.
+        `),
+      )
+    })
+  })
+
   describe("getFiles", () => {
     it("should work with no commits in repo", async () => {
       expect(await handler.getFiles({ path: tmpPath, log })).to.eql([])
diff --git a/garden-service/test/unit/src/vcs/vcs.ts b/garden-service/test/unit/src/vcs/vcs.ts
index 6c81d6442e..9b194ad45e 100644
--- a/garden-service/test/unit/src/vcs/vcs.ts
+++ b/garden-service/test/unit/src/vcs/vcs.ts
@@ -25,6 +25,10 @@ class TestVcsHandler extends VcsHandler {
   name = "test"
   private testVersions: TreeVersions = {}
 
+  async getRepoRoot() {
+    return "/foo"
+  }
+
   async getFiles() {
     return []
   }