Yes, you can freeze mashed potatoes. They keep about 1 month at their best and up to 3 months in the freezer. The catch is dairy: mashed potatoes made with sour cream or cream cheese can turn grainy, and the texture after thawing is looser than fresh.
| Mashed potatoes | How to freeze | How long they keep |
|---|---|---|
| Plain, with butter and milk | Cool, portion, airtight with headspace | 1 month best, 3 months maximum |
| With sour cream or cream cheese | Same, but whisk after thawing | 1 month |
| With chives or fresh herbs | Same | 1 month |
| As a casserole topping | Freeze unbaked, then bake from frozen | 1 month |
| Leftover mash from the fridge | Freeze within 2 days of cooking | 1 month from freezing |
Why dairy is the problem
Mashed potatoes are an emulsion of starch, water and fat. Freezing turns the water into ice crystals that push the starch granules apart and break the fat emulsion, so thawed mash can look watery and taste grainy. The more dairy you add, the more there is to separate.
Butter and milk survive freezing reasonably well. Sour cream, cream cheese and yoghurt are the ones that split, and potatoes mashed with a lot of them come back with a slightly chalky mouthfeel.
How to freeze mashed potatoes properly
- Cool them quickly. Spread the mash in a shallow dish and refrigerate until cold, rather than freezing while warm.
- Portion into meal-sized amounts. A solid block of frozen mash is hard to use and harder to thaw evenly.
- Pack airtight and leave half an inch of headspace, because the water expands as it freezes.
- Freeze flat if you are using bags, so they stack and thaw fast.
- Label with the date and whether dairy was added.
How to reheat frozen mashed potatoes
Thaw overnight in the fridge, then reheat gently. Microwave in a covered bowl, stirring every minute, or warm in a covered pan or a 350°F oven with a splash of milk. Add butter or milk a spoon at a time and whisk to bring the texture back.
You can cook from frozen in an oven dish, but add extra liquid and cover it, or the outside dries before the middle is hot. Either way, reheat to steaming hot throughout, and do not reheat the same portion twice.
Fixing grainy or watery thawed mash
Warm it slowly rather than blasting it, because heat is what finishes the separation. Whisk in warm milk and a little butter, or a spoon of cream cheese if it still looks split. If it stays watery, drain off the liquid before adding more dairy, then beat it back together with a wooden spoon rather than a processor, which will turn it gluey.
For why mash turns gluey in the first place, see why mashed potatoes go gluey.
Common questions
Do mashed potatoes freeze well?
Reasonably well for a month, if you keep dairy light and reheat gently. They are not as good as frozen soup or stew, and fresh mash is always better.
Can you freeze mashed potatoes with sour cream?
Yes, but expect a looser texture. Whisk it after thawing and add a little warm milk to bring it back.
How long can leftover mashed potatoes sit out?
Two hours, as with any cooked food. If they have been out longer, throw them out.
Can you freeze potatoes raw?
No. Raw potatoes go black and mushy in the freezer, because the cell walls break down. Cook them first, whether mashed, roasted or parboiled.
Sources
- Michigan State University Extension, Handling Leftovers Safely: cooling, freezing and reheating cooked leftovers.
- FoodSafety.gov, Cold Food Storage Chart: refrigerator and freezer times for cooked leftovers.
If you are not freezing them, see how long mashed potatoes can stay out.
