How to Blanch Vegetables Before Freezing


Blanching Times for Vegetables - Chart

Freezing is a great way to preserve fresh vegetables from a backyard garden or a local farmers' market when they are in season. And, by freezing vegetables that might not be available year round in the fresh produce section of your local supermarket, you'll be able to enjoy the flavor and health benefits of those vegetables all year round. But before you stash your favorite vegetables in the freezer, you'll need to know whether they should blanched first. To help you with that, you'll find below information about vegetables that need to be blanched, including a chart listing the recommended blanching times for those vegetables, as well as step-by-step instructions on how to blanch fresh vegetables before freezing them.


Why Should Vegetables Be Blanched Before Freezing?

Blanching, or cooking vegetables in boiling water or steam for a set period of time, inhibits the action of enzymes that cause vegetables to develop off-flavors and lose color and nutrients when stored in the freezer for a longer period of time. This process also helps remove dirt and organisms on fresh produce. Blanching time is crucial because underblanching stimulates the action of enzymes, while overblanching causes vegetables to lose color, flavor and nutrients.


Do All Vegetables Need to Be Blanched?

Blanching is recommended for almost all vegetables, but there are also some vegetables that will stay good in the freezer even without blanching. Vegetables that do not need to be blanched before freezing include sweet and hot peppers, ginger root, onions, turmeric root, and raw tomatoes. Also many fresh herbs, such as chives and dill, can be frozen successfully without blanching.


How Long Should Your Blanch Vegetables Before Freezing?

The ideal blanching time for vegetables generally varies from 30 seconds to 10 minutes, depending on the size and texture of the food and the blanching method you are using (water vs steam blanching). For detailed information about how long it takes to blanch a specific vegetables before freezing, have a look at the Blanching Times Chart provided below. Note that the times indicated are for water-blanching (boiling); if you want to steam-blanch your vegetables, multiply the times by 1.5.


Chart: Blanching Times for Common Vegetables

Please note that the following Blanching Times chart is intended as a general guide only – the actual blanching times may differ due to a number of factors.

VegetablePreparation 1Blanching time 2
Artichokes heartsLeave the hearts whole7 minutes
AsparagusTrim; leave whole or cut to your liking2 to 4 minutes
Beans, greenTrim off the hard ends2 to 4 minutes
Beans, snapTrim off the hard ends2 to 4 minutes
Beans, waxTrim off the hard ends2 to 4 minutes
Bell peppers 3Cut into strips2 minutes
BroccoliCut into 1½-inch pieces3 minutes
Brussels sproutsTrim; leave whole3 to 5 minutes
CabbageCut into coarse shreds or thin wedges1 1/2 minutes
CarrotsCut into 1/4-inch slices2 minutes
CauliflowerCut into 1-inch florets
(See also How to Freeze Cauliflower Rice)
3 minutes
CeleryCut into 1-inch lengths3 minutes
ChardChop or leave whole2 minutes
Chinese cabbageShred the cabbage1 1/2 minutes
Collard greensChop or leave whole3 minutes
CornLeave the ears whole7 to 10 minutes
OkraTrim stem ends3 to 4 minutes
Jerusalem artichokesLeave them whole3 to 5 minutes
KaleRemove the tough stems by hand or using a kale trimmer2 minutes
KohlrabiCut into 1/2-inch cubes1 minute
Mustard greensChop or leave whole2 minutes
ParsnipsCut into 1/2-inch cubes2 minutes
Romanesco1-inch pieces3 minutes
Squash, summerCut into 1/2-inch slices3 minutes
SunchokesLeave them whole3 to 5 minutes
Tomatoes 3Leave whole; peel after blanching30 seconds
TurnipsCut into 1/2-inch cubes2 minutes
ZucchiniCut into 1/2-inch slices3 minutes

1 In addition, the vegetables should be rinsed and/or peeled, as needed
2 The times indicated are for water-blanching (boiling). For steam-blanching, multiply the times shown in the chart by 1.5.
3 Can also be frozen without blanching


General Instructions for Blanching Vegetables

  1. Blanch trimmed, rinsed and cut vegetables for the time indicated in the Blanching Times Chart above.
  2. When the blanching time is up, quickly drain the vegetables. A flat stainless steel strainer that you can place over the top of the pot is great for this purpose, but you can also use a regular stainless steel colander.
  3. To stop any carryover cooking, plunge the vegetables into a large bowl filled with ice cubes and cold water, and let the vegetables chill in the ice-water bath for the same amount of time they were boiled or steamed.
  4. Drain thoroughly, and freeze using one of the two methods described below.

How to Freeze Blanched Vegetables

Method 1: Arrange the blanched vegetables in a single layer on a cookie sheet lined with a freezer-safe silicone baking mat or parchment paper, and put the sheet in the freezer. When the vegetables are frozen solid, transfer them to freezer-safe Ziploc bags or containers, and pop them back into the freezer for storage. The great thing about this method is that your blanched vegetables won't fuse together in the freezer, and you'll be able to grab just a few frozen pieces whenever you like.

Method 2: Divide the blanched vegetables into portions that work for your needs. Then, package the portions in freezer bags, leaving as little air inside as possible. A vacuum sealer is perfect for this purpose, but you can also use a straw tucked in the corner of the bag to suck out the air! This method works well if you have a good idea of how you're going to use your frozen vegetables so you are able to divide the vegetables into portions that are just the right size. This is also the preferred method for freezing leafy green vegetables such as kale or collards.