diff --git a/src/cache/inmemory/inMemoryCache.ts b/src/cache/inmemory/inMemoryCache.ts
index f9ef73954d0..6bc9d859bb8 100644
--- a/src/cache/inmemory/inMemoryCache.ts
+++ b/src/cache/inmemory/inMemoryCache.ts
@@ -20,7 +20,7 @@ import {
 import { StoreReader } from './readFromStore';
 import { StoreWriter } from './writeToStore';
 import { EntityStore, supportsResultCaching } from './entityStore';
-import { makeVar, forgetCache } from './reactiveVars';
+import { makeVar, forgetCache, recallCache } from './reactiveVars';
 import {
   defaultDataIdFromObject,
   PossibleTypesMap,
@@ -194,6 +194,19 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
   }
 
   public watch(watch: Cache.WatchOptions): () => void {
+    if (!this.watches.size) {
+      // In case we previously called forgetCache(this) because
+      // this.watches became empty (see below), reattach this cache to any
+      // reactive variables on which it previously depended. It might seem
+      // paradoxical that we're able to recall something we supposedly
+      // forgot, but the point of calling forgetCache(this) is to silence
+      // useless broadcasts while this.watches is empty, and to allow the
+      // cache to be garbage collected. If, however, we manage to call
+      // recallCache(this) here, this cache object must not have been
+      // garbage collected yet, and should resume receiving updates from
+      // reactive variables, now that it has a watcher to notify.
+      recallCache(this);
+    }
     this.watches.add(watch);
     if (watch.immediate) {
       this.maybeBroadcastWatch(watch);
diff --git a/src/cache/inmemory/reactiveVars.ts b/src/cache/inmemory/reactiveVars.ts
index 409c8611837..75761741901 100644
--- a/src/cache/inmemory/reactiveVars.ts
+++ b/src/cache/inmemory/reactiveVars.ts
@@ -35,10 +35,20 @@ const varsByCache = new WeakMap<ApolloCache<any>, Set<ReactiveVar<any>>>();
 
 export function forgetCache(cache: ApolloCache<any>) {
   const vars = varsByCache.get(cache);
-  if (vars) {
-    consumeAndIterate(vars, rv => rv.forgetCache(cache));
-    varsByCache.delete(cache);
-  }
+  if (vars) vars.forEach(rv => rv.forgetCache(cache));
+}
+
+// Calling forgetCache(cache) serves to silence broadcasts and allows the
+// cache to be garbage collected. However, the varsByCache WeakMap
+// preserves the set of reactive variables that were previously associated
+// with this cache, which makes it possible to "recall" the cache at a
+// later time, by reattaching it to those variables. If the cache has been
+// garbage collected in the meantime, because it is no longer reachable,
+// you won't be able to call recallCache(cache), and the cache will
+// automatically disappear from the varsByCache WeakMap.
+export function recallCache(cache: ApolloCache<any>) {
+  const vars = varsByCache.get(cache);
+  if (vars) vars.forEach(rv => rv.attachCache(cache));
 }
 
 export function makeVar<T>(value: T): ReactiveVar<T> {
@@ -86,14 +96,7 @@ export function makeVar<T>(value: T): ReactiveVar<T> {
     return rv;
   };
 
-  rv.forgetCache = cache => {
-    const deleted = caches.delete(cache);
-    if (deleted) {
-      const vars = varsByCache.get(cache);
-      if (vars) vars.delete(rv);
-    }
-    return deleted;
-  };
+  rv.forgetCache = cache => caches.delete(cache);
 
   return rv;
 }