diff --git a/comfy/samplers.py b/comfy/samplers.py
index 9eee25a9..5b01d48f 100644
--- a/comfy/samplers.py
+++ b/comfy/samplers.py
@@ -17,6 +17,14 @@ def sampling_function(model_function, x, timestep, uncond, cond, cond_scale, con
         def get_area_and_mult(cond, x_in, cond_concat_in, timestep_in):
             area = (x_in.shape[2], x_in.shape[3], 0, 0)
             strength = 1.0
+            if 'timestep_start' in cond[1]:
+                timestep_start = cond[1]['timestep_start']
+                if timestep_in > timestep_start:
+                    return None
+            if 'timestep_end' in cond[1]:
+                timestep_end = cond[1]['timestep_end']
+                if timestep_in < timestep_end:
+                    return None
             if 'area' in cond[1]:
                 area = cond[1]['area']
             if 'strength' in cond[1]:
@@ -428,6 +436,25 @@ def create_cond_with_same_area_if_none(conds, c):
     n = c[1].copy()
     conds += [[smallest[0], n]]
 
+def calculate_start_end_timesteps(model, conds):
+    for t in range(len(conds)):
+        x = conds[t]
+
+        timestep_start = None
+        timestep_end = None
+        if 'start_percent' in x[1]:
+            timestep_start = model.sigma_to_t(model.t_to_sigma(torch.tensor(x[1]['start_percent'] * 999.0)))
+        if 'end_percent' in x[1]:
+            timestep_end = model.sigma_to_t(model.t_to_sigma(torch.tensor(x[1]['end_percent'] * 999.0)))
+
+        if (timestep_start is not None) or (timestep_end is not None):
+            n = x[1].copy()
+            if (timestep_start is not None):
+                n['timestep_start'] = timestep_start
+            if (timestep_end is not None):
+                n['timestep_end'] = timestep_end
+            conds[t] = [x[0], n]
+
 def apply_empty_x_to_equal_area(conds, uncond, name, uncond_fill_func):
     cond_cnets = []
     cond_other = []
@@ -571,6 +598,9 @@ class KSampler:
         resolve_cond_masks(positive, noise.shape[2], noise.shape[3], self.device)
         resolve_cond_masks(negative, noise.shape[2], noise.shape[3], self.device)
 
+        calculate_start_end_timesteps(self.model_wrap, negative)
+        calculate_start_end_timesteps(self.model_wrap, positive)
+
         #make sure each cond area has an opposite one with the same area
         for c in positive:
             create_cond_with_same_area_if_none(negative, c)
diff --git a/nodes.py b/nodes.py
index a1c4b843..db39c0ce 100644
--- a/nodes.py
+++ b/nodes.py
@@ -204,6 +204,28 @@ class ConditioningZeroOut:
             c.append(n)
         return (c, )
 
+class ConditioningSetTimestepRange:
+    @classmethod
+    def INPUT_TYPES(s):
+        return {"required": {"conditioning": ("CONDITIONING", ),
+                             "start": ("FLOAT", {"default": 1.0, "min": 0.0, "max": 1.0, "step": 0.001}),
+                             "end": ("FLOAT", {"default": 0.0, "min": 0.0, "max": 1.0, "step": 0.001})
+                             }}
+    RETURN_TYPES = ("CONDITIONING",)
+    FUNCTION = "set_range"
+
+    CATEGORY = "advanced/conditioning"
+
+    def set_range(self, conditioning, start, end):
+        c = []
+        for t in conditioning:
+            d = t[1].copy()
+            d['start_percent'] = start
+            d['end_percent'] = end
+            n = [t[0], d]
+            c.append(n)
+        return (c, )
+
 class VAEDecode:
     @classmethod
     def INPUT_TYPES(s):
@@ -1444,6 +1466,7 @@ NODE_CLASS_MAPPINGS = {
     "SaveLatent": SaveLatent,
 
     "ConditioningZeroOut": ConditioningZeroOut,
+    "ConditioningSetTimestepRange": ConditioningSetTimestepRange,
 }
 
 NODE_DISPLAY_NAME_MAPPINGS = {