Store-bought Zesty Italian can sit in a pantry for a year and shrug. Your mason jar of lemon-garlic vinaigrette cannot. Homemade dressing is fresh, once-living ingredients with nothing holding the line behind them, unlike the bottled stuff packed with stabilizers and more sugar than you’d guess.
Most of the time this is a waste-and-taste question. Once in a while, specifically when raw garlic meets a lot of oil, it’s an actual food safety question. Here’s how to tell those apart.
How long does homemade salad dressing last?
| Dressing type | Keep it | Where the number comes from |
|---|---|---|
| Plain vinaigrette (oil, vinegar, dried herbs and spices) | Up to 2 weeks | Cooperative Extension: simple vinaigrettes keep up to 2 weeks refrigerated |
| Vinaigrette with fresh garlic, shallots, onion, or fresh herbs | Up to 1 week | Same Extension answer, for dressings “made with fresh ingredients, like onions and herbs” |
| Citrus-forward dressing with fresh lemon or lime juice | Up to 1 week | Same Extension answer: the dressing in that question contained lemon juice, and it is the “fresh ingredients” case assigned 1 week |
| Creamy dressing (mayo, sour cream, yogurt, buttermilk) | 3 to 4 days | Closest mayo-bound comparison: FoodSafety.gov gives 3 to 4 days for egg, chicken, ham, tuna, and macaroni salads; USDA’s own page says 3 to 5 |
| Raw-egg dressing (classic Caesar, homemade mayo or aioli) | Same day, or use pasteurized eggs | USDA FSIS advises against foods with raw or undercooked eggs, naming Caesar salad and homemade mayonnaise |
| Raw garlic or fresh herbs in oil, no added acid (infused oil, garlic confit, pesto) | 4 days, fridge only, or freeze | Oregon State University Extension and the National Center for Home Food Preservation |
Worth being honest about the limits: the federal cold-storage chart doesn’t list homemade salad dressing at all, so those rows lean on the closest published references. Read the top four as quality windows. The raw-egg row and the garlic-in-oil row are the two safety limits.
The pattern is simple. More acid buys you time. More fresh, once-living ingredients takes it away. Oil, red wine vinegar, and dried oregano coasts for two weeks. A ranch with fresh dill and buttermilk is on a much shorter clock.
Do you have to refrigerate homemade salad dressing?
Anything with fresh produce, dairy, or egg in it, yes. That part isn’t a preference. A plain oil, vinegar, and dried-herb vinaigrette is the one case where the perishable-food rules don’t squarely apply, and we still keep it cold by default rather than sort out which jar is which. FDA advises keeping your refrigerator at 40°F or below and getting perishable food back in the cold within 2 hours. Oil keeps better cool and dark too. UC Davis recommends storing olive oil in a cool, dark place to slow oxidation.
One placement detail nobody mentions: USDA says don’t store perishable foods in the door, because door bin temperatures fluctuate more than the main cabinet. That door is exactly where most people park the dressing jar. Move it to a shelf.
Use glass while you’re at it. Plastic absorbs odors and stains, and glass is non-reactive, which matters when the jar is half vinegar. A 16-ounce mason jar is the right size for a weekly batch.
The raw garlic in oil rule you actually need to know
This is the one real safety issue here. Oregon State University Extension explains that low-acid foods stored in oil create “an oxygen-free environment which is perfect for growth” of Clostridium botulinum. The National Center for Home Food Preservation adds that garlic-in-oil mixtures left at room temperature are at risk for the development of botulism.
So the rule is short. Homemade flavored oils, including pesto and that trendy jar of garlic confit, go in the fridge and get used within 4 days, or into the freezer for longer storage. Oregon State applies the same 4-day limit even when the garlic or herbs are dried, which surprises people. Label the container with the date you made it and the date four days later when it has to be used or frozen.
Commercial garlic-in-oil is either acidified during manufacturing or made with specific microbial inhibitors, which is why it can sit on a store shelf. Your kitchen isn’t doing that, and splashing lemon juice into a jar of garlic and oil is not acidification. For a shelf-stable infused oil there is a tested Extension procedure, published as PNW 664, Making Garlic- and Herb-Infused Oils at Home. It covers a specific, limited set of herbs, and the directions have to be followed exactly. Read the publication itself before trying it, not a summary of it.
The line to watch is whether you’ve made a dressing or an infused oil. If you could pour it over a salad and taste the acid, it’s a dressing, and Extension guidance puts fresh-ingredient dressings at one week. If it’s basically garlic sitting in fat, it’s an infused oil, and that caps at 4 days.
Creamy dressings get the shortest quality window
Anything with mayo, sour cream, yogurt, or buttermilk is on a 3 to 4 day plan, borrowed from the federal listing for egg, chicken, ham, tuna, and macaroni salads. The two government pages disagree by a day, 3 to 4 on FoodSafety.gov versus 3 to 5 on USDA’s refrigeration page, so take the shorter one.
One creamy dressing sits in its own category: a real Caesar or a homemade aioli is raw egg yolk. USDA’s Food Safety and Inspection Service advises everyone against foods containing raw or undercooked eggs, naming Caesar salad and homemade mayonnaise specifically. FSIS says to cook dishes containing raw eggs immediately, or refrigerate and cook them within 24 hours, a much tighter clock than the 3 to 4 days above, and that assumes the dish gets cooked at all. The fix FSIS offers is pasteurized in-shell eggs or egg products, which “may be used safely without cooking”, or heating the eggs with the liquid ingredients to 160°F before you combine everything. Want to skip the raw egg and the dairy clock in one move? A tahini-based vegan Caesar does both.
Why your vinaigrette turns solid in the fridge
You’ll pull the jar out and find a cloudy, semi-solid sludge. Don’t throw it away. UC Davis says it’s normal for olive oil to get cloudy or to solidify in cold temperatures because of waxes naturally present in olives, and that this doesn’t affect the oil’s quality or safety. Cloudy and thick, though, not a solid brick.
What it doesn’t do is prove you bought the good stuff. That “real olive oil solidifies in the fridge” trick gets repeated constantly, and UC Davis Olive Center testing found the fridge test unreliable for detecting either the purity or the quality of olive oil. That’s why the test fails: their samples never fully solidified, even after 180 hours cold. Set the jar on the counter for 15 to 20 minutes, shake it hard, and pour.
How to tell when dressing has gone bad
Here’s the uncomfortable part. FDA warns that food can make you very sick even when it doesn’t look, smell, or taste spoiled, so your nose is a backup system, not the primary one. Write the date on the lid and go by that first.
That said, obvious signals still count. If the oil smells metallic, soapy, or like wet cardboard, it’s gone rancid. Any fuzzy growth means the whole jar goes in the trash, not a scrape-and-save operation. USDA is direct about this for high-moisture foods: they can be contaminated below the surface, and mold roots run deeper than the part you can see.
Separation is fine. We aren’t adding xanthan gum here. A hard shake should bring it back. If it stays broken after that, the mustard or the dairy proteins have given up.
Keeping a jar of something homemade in the fridge makes a Tuesday night salad feel less like a chore, and if you’re picking what to whisk up next, these homemade dressings with an extra fiber kick are where I’d start. That same jar earns its keep in summer, especially once you know how to pack a cold pasta salad for picnics so it arrives crisp instead of questionable. Glass jar, shelf not door, date on the lid, and the garlic-in-oil clock in the back of your mind.
