Which preservation method suits your herbs?
Tell me the herb and what you want out of it, and I will give you the method, the steps and how long it lasts.
Soft herbs and woody herbs are not the same problem
Soft herbs have tender, high-moisture leaves. Basil, parsley, coriander, mint, dill, tarragon, chives and chervil. The flavour lives in volatile oils that evaporate, and drying drives most of them off. Dry a soft herb and you get colour and fibre with very little taste.
Woody herbs have tough, low-moisture leaves with a strong cell structure. Rosemary, thyme, oregano, sage, marjoram and bay. Their oils are more stable, they survive drying well, and in some cases drying concentrates the flavour rather than losing it.
Once you know which group you have, the method mostly picks itself.
Which method suits which herb
| Herb | Type | Best method | Avoid |
|---|---|---|---|
| Basil | Soft | Freeze in oil or as pesto | Drying. It loses almost everything |
| Parsley | Soft | Freeze chopped in oil or butter | Drying. It goes dull and grassy |
| Coriander | Soft | Freeze as a paste | Drying. It loses the citrus note entirely |
| Mint | Soft | Freeze in ice cubes or dry for tea | Drying if you want it fresh-tasting |
| Dill | Soft | Freeze chopped | Drying. It fades quickly |
| Chives | Soft | Freeze snipped | Drying. They turn to grey straw |
| Rosemary | Woody | Dry, or freeze whole sprigs | Nothing much. It is very forgiving |
| Thyme | Woody | Dry whole on the stem | Nothing much |
| Oregano | Woody | Dry. It improves | Nothing much |
| Sage | Woody | Dry, or fry in butter and freeze | Nothing much |
| Bay | Woody | Dry whole leaves | Nothing much |
The methods, and how they actually work
- Drying. Best for woody herbs. Hang in small bunches somewhere dark, dry and airy, or spread on a tray. Darkness matters, because light bleaches the colour out. Two weeks is usually enough.
- Freezing whole. Works for woody herbs too. Strip the leaves, freeze on a tray and bag. Rosemary and thyme come out of the freezer close to how they went in.
- Freezing in oil. The best method for soft herbs. Chop the herb, pack into an ice cube tray, cover with olive oil and freeze. Drop a cube straight into a hot pan.
- Freezing as a paste. Blend soft herbs with a little oil and salt, then freeze in a bag flattened flat so you can break off pieces.
- Ice cubes for drinks. Mint, lemon balm and verbena freeze well in water for summer drinks, though the leaves will go dark.
- Infusing in oil or vinegar. Good for rosemary, thyme and tarragon. Keep it in the fridge and use within a couple of weeks.
- Pesto and sauces. Basil, parsley and coriander all freeze beautifully as a pesto base without the cheese.
The safety point that is easy to miss
Herbs in oil at room temperature are a genuine botulism risk. Garlic in oil is the classic case, but any fresh herb in oil carries the same problem, because the oil creates an oxygen-free environment where the bacteria can grow.
The rule is simple: anything preserved in oil goes in the fridge or the freezer, never in the cupboard. A jar of herb oil on a shelf is a risk. The same jar in the fridge, used within a couple of weeks, is fine.
What I do now
Everything soft goes in the freezer in oil. Basil, parsley, coriander, dill and chives all get chopped, packed into an ice cube tray and covered with oil. It takes twenty minutes for a whole season and I use them all winter.
Everything woody gets hung in the dark in small bunches. Rosemary, thyme, oregano and sage. It takes ten minutes to set up and they are better dried than fresh for anything cooked.
The one thing I stopped doing is drying soft herbs. It was never worth the afternoon.
I dried a whole season of basil one year. It took me an afternoon, it smelled wonderful, and the result was a jar of green dust that tasted of hay.
That is the thing nobody tells you about drying: it works brilliantly for some herbs and destroys others completely. Rosemary dried is almost as good as fresh. Basil dried is a different, much worse ingredient.
The herb tells you which method to use. You just have to know which is which.
Frequently Asked Questions
Freeze it in oil, either chopped in an ice cube tray or blended into a pesto base. Drying basil destroys most of its flavour, because the oils that make it taste like basil evaporate.