A big bunch of parsley looks like excellent value until half of it goes slimy in the fridge. Garden herbs can cause the same problem when they grow faster than you can cook with them. Freezing is a practical way to preserve the flavour of fresh leaves for sauces, soups and stews, although most herbs lose the crisp texture that makes them attractive as fresh garnishes.
You can freeze washed and dried herbs in bags, chop them into water-filled ice cube trays or freeze them with oil for cooked dishes. The method depends on the herb and how you intend to use it later.
Decide whether freezing suits the herb
Parsley, dill, chives, coriander and basil are commonly frozen. They are particularly useful in dishes where they will be chopped and heated.
Tougher woody herbs such as rosemary or thyme may also be frozen, though many people choose to dry some of those varieties instead. The best preservation method depends on flavour and the dish you usually make.
Don't expect frozen mint leaves to look like fresh ones on top of a dessert. Their cell structure changes during freezing, so appearance and texture will be different after thawing.
Choose healthy leaves, not old rubbish
Select sound herbs that still smell fresh. Remove yellowed, slimy, mouldy or badly damaged leaves. Freezing cannot restore the quality of material already spoiling.
If you're harvesting from the garden, cut herbs during suitable dry weather when practical. Shake away insects and inspect stems before bringing them indoors.
Work in small quantities so herbs do not wilt on the counter while you're preparing trays and bags. Gather the scissors, clean board and freezer packaging before you begin.
Wash and dry them properly
Penn State Extension advises rinsing herbs in clean water and gently patting dry or using a salad spinner. The aim is to remove dirt without crushing delicate foliage.
Strip leaves from tough stems where necessary. Some soft stems can be chopped and used, depending on the herb and recipe, so you don't have to discard everything below the leaf.
Drying matters if you're freezing loose leaves. Excess water forms ice around the foliage, making it clump and develop more frost during storage.
Method one: freeze herbs loosely
Spread suitably dried leaves or chopped herbs in a thin layer on a freezer-safe tray. Freeze until firm, then transfer promptly to suitable bags or sealed containers.
This works when you want to sprinkle a small handful into a pan without defrosting an entire batch. Pack in modest quantities so you don't repeatedly open a large bag.
Some herbs will darken or become brittle when frozen; that's not necessarily spoilage. Use them from frozen in cooking rather than expecting them to survive delicate handling after thawing.
Method two: make herb cubes with water
Chop the leaves to roughly the size you'd use for cooking. Penn State Extension suggests putting about a tablespoon of herbs into each compartment of an ice cube tray.
Add water so the herbs are mostly covered and freeze. You can top up the trays as directed once the first layer sets, making cubes that contain the herbs securely.
When solid, transfer the cubes to a labelled freezer bag. Drop them into soups, stocks or stews during cooking. Water-based cubes are convenient for dishes where an extra splash of liquid won't matter.
Method three: freeze herbs with oil
Basil and some other herbs preserve their colour better when chopped and mixed with oil before freezing. Penn State Extension provides a specific herb-and-oil method for frozen use.
Portion the mixture into small freezer-safe containers or ice cube trays. Once frozen, keep it frozen until ready to add to a cooked dish. Oil mixtures may remain softer than plain water cubes, so use a clean utensil to remove portions.
Never store homemade herbs in oil at room temperature. That can create conditions that allow dangerous microorganisms to grow. Penn State explicitly warns that oil should be added to herbs only when the mixture will be frozen.
Freeze a flat bag of herb paste
For sauces, a thin flattened bag of chopped herbs with suitable oil can be especially practical. Press the mixture into an even layer, remove excess air and seal it securely.
Lay the bag flat in the freezer. When frozen, you may be able to break off a piece of the thin layer rather than defrosting the whole quantity.
Keep it clearly labelled because frozen pesto base, basil paste and parsley oil can look similar. Note whether it contains garlic, nuts or other ingredients that matter for the eventual recipe.
How to freeze basil specifically
Basil is delicate and often blackens when handled roughly. Choose healthy leaves, wash gently and dry them before chopping.
For pesto or cooked tomato sauces, freezing chopped basil with a suitable amount of oil may be more convenient than loose leaves. If you want more flexibility, freeze plain chopped basil in water-based cubes instead.
Do not assume a frozen basil leaf will work as a fresh whole leaf in a caprese salad. Its aroma may still be useful, but the texture is unlikely to look or feel the same.
How to freeze parsley and coriander
Remove tough or yellowing stems and wash the bunch carefully. Chop the leaves if you usually add them chopped to dishes; keep some whole if you prefer to decide later.
Freeze plain in small labelled bags or use water cubes for curries, soups and sauces. Portioning matters because a large block is difficult to measure.
Coriander in particular loses its fresh crisp appearance after thawing. Add frozen leaves to hot dishes for flavour, while keeping fresh coriander for final garnishes where appearance matters.
How to freeze chives and dill
Snip chives into small pieces with kitchen scissors rather than crushing them with a heavy knife. Dry them well and pack loosely in a freezer bag or a small container.
Dill can be chopped and frozen similarly, or portioned into water cubes for soups and fish dishes where a little additional liquid is welcome.
These fine herbs freeze quickly. Transfer them into sealed packaging promptly to avoid excessive freezer odours and drying.
Label portions for your recipes
Write the herb name, whether it's plain, in water or in oil, and the freezing date. Include approximate portion sizes if they're not obvious.
Strong-smelling herbs may transfer aromas if the packaging isn't secure. Penn State suggests extra wrapping or appropriate sealed jars for strongly scented varieties.
Place newly prepared packages flat until frozen, then organise them together so you're not searching through unlabeled green cubes when dinner is nearly ready.
Using frozen herbs safely
Frozen herbs can usually go straight into a hot dish. They thaw rapidly and mix through sauces, soups and stews without a separate defrosting stage.
Freezing slows spoilage but does not sterilise food. Start with clean wholesome herbs, use hygienic equipment and keep the finished portions in a properly functioning freezer.
If you combine herbs with other ingredients such as cheese, nuts or dairy, follow food-safety storage advice for the whole mixture, not just the herb.
Common mistakes with frozen herbs
The first is packing leaves when they're still dripping wet. The result may be a block of ice rather than a useful sprinkle of herbs.
The second is expecting frozen leaves to work as fresh salad garnish. Use frozen herbs where taste matters more than a crisp whole-leaf appearance.
The third is leaving herb-infused oil on the worktop. Freezing it promptly is essential to the method described here; room-temperature storage is a different and potentially unsafe preservation process.
Try a small batch of two or three methods. You may find parsley works best loose, basil works best in frozen paste and dill is most convenient in cubes. Practical portions matter more than keeping every herb in the same format.