The short answer: for rosemary infused olive oil, warm 250 ml of olive oil with 2 tablespoons of dried rosemary over low heat until tiny bubbles appear, about 5 minutes. Take it off the heat, let it steep for an hour, then strain. Use dried rosemary for an oil that keeps about a month in the fridge. With fresh rosemary, use it within 4 days.
A bowl of rosemary infused olive oil with warm bread takes 10 minutes of work and an hour of steeping. The same oil makes roast potatoes, lamb and focaccia taste of rosemary right through. This guide covers a quick warm method, a slow hands-off method, a bread dip, and the one rule that keeps the oil safe: dried rosemary for keeping, fresh rosemary for eating soon.
| At a glance | |
|---|---|
| Ratio | 250 ml olive oil to 2 tablespoons dried rosemary |
| Time | 10 minutes plus 1 hour steeping |
| Best rosemary | Dried, for an oil that keeps |
| Keeps | About 1 month in the fridge (dried rosemary) |
Ingredients
- 250 ml (1 cup) olive oil, extra virgin or mild
- 2 tbsp dried rosemary, or 4 dried sprigs
- Optional: 1 strip of dried lemon peel, ½ tsp black peppercorns
Which olive oil? A fruity extra virgin olive oil is best for dipping and drizzling. A milder olive oil suits roasting, where the rosemary should lead.
How to make rosemary infused olive oil
- Bruise the rosemary. Roll dried sprigs between your palms, or crush dried leaves lightly. This helps the flavour come out.
- Warm gently. Put the oil and rosemary in a small pan over low heat. Warm it for about 5 minutes, until tiny bubbles form around the leaves. It should never fry or sizzle.
- Steep. Take the pan off the heat. Cover and leave it for 1 hour as it cools.
- Strain. Pour it through a fine sieve lined with a coffee filter into a clean, dry bottle.
- Store. Close the bottle, label it with the date and keep it in the fridge.
Dried or fresh rosemary?
Fresh rosemary carries water. In oil, that water lets harmful bacteria grow at room temperature, and you cannot taste or smell them. Dried rosemary avoids that problem, which is why it is the better choice for an oil you want to keep.
| Dried rosemary | Fresh rosemary | |
|---|---|---|
| Flavour | Deep, warm, piney | Bright and green |
| Fridge | About 1 month | Use within 4 days |
| Freezer | Up to 3 months | Up to 3 months |
| Best for | Bottles to keep | Oil you use the same week |
To dry your own rosemary, hang a few sprigs in a warm, airy room for 1 to 2 weeks until the leaves snap. A sprig in the bottle is fine only if it snaps when you bend it.
A slow, hands-off version
For a deeper rosemary flavour without watching the pan, use the NOIDS Herb Lab.
- Put 2 tablespoons of dried rosemary and 250 ml of olive oil into the Glass. Stay under the MAX mark.
- Cover with the Dish Lid and place the Glass in the Main Body.
- Turn the Rotary Control to Oil. The cycle holds 100 °C (212 °F) for about 120 to 180 minutes, then cools by itself.
- Strain through the Filter Set into a clean bottle.
Rosemary bread dip
Pour 4 tablespoons of rosemary oil into a shallow bowl. Add a pinch of flaky salt, a little black pepper and a few drops of balsamic vinegar. Serve with warm bread or focaccia.
More ways to use rosemary oil
- Roast potatoes: toss them in the oil before roasting.
- Lamb and chicken: brush over the meat before and after cooking.
- Focaccia: drizzle generously over the dough before baking.
- White beans: warm cannellini beans with the oil, garlic and lemon.
- Soup: a few drops on tomato or white bean soup.
- Eggs: fry eggs in a spoonful and finish with flaky salt and black pepper.
For other flavours made the same way, see our complete guide to infused olive oil and our lemon-infused olive oil.
Mistakes to avoid
- Too much heat: if the rosemary sizzles or darkens, the oil turns bitter. Keep the heat low.
- Wet bottles: a drop of water left in the bottle shortens the oil's life. Dry bottles fully after washing.
- Keeping it on the shelf: even with dried rosemary, the fridge is the safe place.
- Too long in the light: light fades the flavour. Use a dark bottle and keep it in the fridge.
- Skipping the label: write the date on the bottle so you know when to use it up.
Questions
How long does rosemary infused olive oil last?
Made with dried rosemary and strained, about a month in the fridge. Penn State Extension allows up to 3 months; we use the shorter time. Made with fresh rosemary, use it within 4 days, or freeze it.
Can I leave a rosemary sprig in the bottle?
Only a fully dried one. A fresh sprig adds water, which is not safe in oil kept for more than a few days.
Why does my rosemary oil go cloudy in the fridge?
Olive oil thickens and clouds when cold. That is normal. Leave it out for 15 minutes before using, and it clears again.
Can I cook with rosemary infused olive oil?
Yes, for roasting and gentle frying. For the best flavour, add some at the end too.
Should I use extra virgin olive oil?
For dipping and drizzling, yes. For roasting, a milder olive oil lets the rosemary come through more.
