Collard greens can be canned safely, but only as a hot pack in a pressure canner. A boiling-water bath, even with vinegar, does not get hot enough to destroy Clostridium botulinum spores in this low-acid vegetable. The tested process, published by the National Center for Home Food Preservation for spinach and other greens, is 70 minutes for pints and 90 minutes for quarts, with pressure adjusted for your altitude and canner type.
That long time is not a suggestion. Greens mat together in the jar, so heat moves slowly through the pack. Shorter times, added meat, or a water bath leave a real botulism risk. Done by the tested method, canned collards keep for about a year and reheat into a plain base you season at the table.
Why collards have to be pressure canned
Collards, like other fresh vegetables, have a pH above 4.6. In a sealed jar they sit in the conditions botulinum spores need: moisture, low acid, and little oxygen. Those spores survive 212°F boiling water. They are destroyed only when the food is held at about 240°F, which a pressure canner reaches and a stockpot does not.
Vinegar does not fix this. Extension specialists have found no research-tested recipe for pickled collard greens. pH is only one factor labs measure when they develop a process. A home pH strip cannot turn an untested water-bath jar into a safe one.
A pressure cooker or electric multi-cooker is not a substitute. USDA processes assume a pressure canner large enough to hold at least four upright quart jars, with a rack, a vent, and a weighted or dial gauge.
How much to pick and what to set out
Plan on about 28 pounds of fresh collards for a canner load of 7 quarts, or about 18 pounds for 9 pints. Yield varies with stem size and how tightly the leaves wilt, but a working average is about 4 pounds of raw greens per finished quart.
Use only freshly harvested leaves that are tender and a good color. Discard wilted, yellowed, diseased, or insect-damaged leaves. Older, woody collards can still be canned if you cut out the midribs, but the jar will be stringier.
You will also need:
- A pressure canner, jars, new lids, and rings
- A blancher basket or cheesecloth for steaming
- Canning salt, optional: 1/4 teaspoon per pint or 1/2 teaspoon per quart
- Boiling water for covering the greens
- Jar lifter, bubble remover, and a clean cloth for rims
Salt is for flavor only. It does not preserve the greens.
How to prepare and pack collard greens
Wash small handfuls at a time in several changes of water until the rinse runs clear. Grit hides in the ribbed leaves, and sand in a jar will not cook out later. Drain, then cut out tough stems and thick midribs.
This process is hot pack only. There is no tested raw pack.
- Steam 1 pound of greens at a time in a blancher basket or cheesecloth bag for 3 to 5 minutes, until the leaves are well wilted. Collards are thicker than spinach, so they usually need the full 5 minutes. Do not steam a huge pot at once. The center will stay raw while the outside overcooks.
- Keep jars hot. Have a kettle of fresh water at a boil.
- If you want salt, add it to the jar now.
- Pack the hot greens loosely. Pressing them in to “fill the jar” is the most common reason liquid siphons out and heat fails to reach the center. Penn State Extension notes that the long process exists exactly because packed leaves block liquid circulation.
- Cover with fresh boiling water, leaving 1 inch of headspace. Do not use ham broth, potlikker from a seasoned pot, oil, or butter.
- Run a bubble remover down the inside of the jar several times. Leaves trap air pockets. Add more boiling water if the level drops, still keeping 1 inch of headspace.
- Wipe the rim clean, set the lid, and tighten the ring fingertip-tight.
Work in batches so the blanched greens stay hot while you fill.
Processing times and altitude pressure
Vent the canner before you start the clock. Put the lid on with the vent open, heat until steam flows steadily, and let it exhaust for 10 minutes. Then close the vent or set the weight. Start timing only when the gauge reaches the pressure below. If pressure drops, bring it back up and restart the full time.
Dial-gauge canner, hot pack:
| Jar | Time | 0–2,000 ft | 2,001–4,000 ft | 4,001–6,000 ft | 6,001–8,000 ft |
|---|---|---|---|---|---|
| Pints | 70 min | 11 lb | 12 lb | 13 lb | 14 lb |
| Quarts | 90 min | 11 lb | 12 lb | 13 lb | 14 lb |
Weighted-gauge canner, hot pack:
| Jar | Time | 0–1,000 ft | Above 1,000 ft |
|---|---|---|---|
| Pints | 70 min | 10 lb | 15 lb |
| Quarts | 90 min | 10 lb | 15 lb |
These figures come from the National Center for Home Food Preservation, adapted from the USDA Complete Guide to Home Canning. Have a dial gauge tested each year. A gauge that reads low can underprocess the jars.
When time is up, turn off the heat and let the canner depressurize on its own. Do not run cold water over it or open the vent early. Cooling time is part of the process. After the canner is fully depressurized, wait a few minutes, open the lid away from your face, and remove jars to a towel. Leave them undisturbed for 12 to 24 hours.
What you cannot put in the jar
Plain greens in boiling water is the tested product. These additions have no established home-canning process and should wait until you open the jar:
- Ham hock, bacon, salt pork, smoked turkey, or any other meat
- Meat broth or potlikker cooked with meat
- Oil, butter, or fat
- Flour or cornstarch thickeners
- Large amounts of onion, garlic, or pepper beyond what a tested greens recipe allows, which is none
A little vinegar in the cooking pot does not convert this into a pickle. People who water-bath collards “with a lot of vinegar” are using an untested method. Extension guidance is to discard those jars rather than try to check them with a pH meter.
Season after opening. A spoon of rendered bacon, a splash of vinegar, hot sauce, or a simmer with a piece of smoked meat gives the pot-greens flavor without changing the canning process.
Siphoning, seals, and storage
Some liquid loss is common with greens because the pack is dense and the process is long. If the jar sealed and at least half the contents are still covered, the food is considered safe. Uncovered leaves may darken. Use those jars first, and do not open them to add water for shelf storage.
If more than half the liquid is gone, heat penetration may have been poor. Refrigerate and use within 2 to 3 days, or freeze. Jars that never seal can be reprocessed within 24 hours with a new lid, or refrigerated or frozen.
Store sealed jars in a cool, dark place, ideally under 95°F and away from the stove or an attic. Quality is best within a year. Before you use a jar, check the seal, and look for spurting liquid, a broken seal, mold, foam, or an off smell. If any of those show up, discard the food without tasting it. Boil suspicious low-acid food only as a last check, and throw it out if it foams or smells wrong. When in doubt, throw it out.
USDA and CDC guidance is to boil home-canned low-acid foods before serving: 10 minutes at altitudes under 1,000 feet, plus 1 minute for each additional 1,000 feet. Spinach is called out separately for a 20-minute boil because it is so dense. Collards are processed on that same greens schedule for the same reason, so the longer boil is the cautious choice.
Canning or freezing
Pressure canning wins on pantry space and shelf life without electricity. Freezing usually wins on texture and color. Michigan State University Extension notes that freezing greens gives a better product even though canning is allowed.
For the freezer, wash and stem the leaves, water-blanch collards for 3 minutes, cool quickly, drain well, and pack with 1/2 inch of headspace. Frozen collards keep their bite better if you plan to sauté or simmer them briefly. Canned collards are already very soft, closer to long-simmered pot greens, which is what many people want beside beans or cornbread.
Drying is a poor fit for collards as a side dish. The leaves are mostly water, so they collapse into a crisp that works better crumbled into soup than served as greens.
Mistakes that make a batch unsafe or poor
- Water-bath or steam canning. Not safe for collards.
- Copying a family recipe that adds meat and shortens the time. Meat needs its own tested process. Combining it with greens has not been tested for home canning.
- Packing the jar hard. Loose pack is a safety step, not a yield tip.
- Starting the timer when the lid goes on, or skipping the 10-minute vent. Trapped air keeps the canner from reaching true processing temperature.
- Force-cooling the canner. That pulls liquid out and can underprocess the jars.
- Using an untested electric multi-cooker “canning” button for this USDA process.
Thick collard leaves do hold up better than spinach under the same process. Expect silky greens, not a bright sauté.
How to use a jar
Drain most of the liquid into a saucepan, or keep it if you like potlikker. Bring the greens and liquid to a boil and hold the boil for the time above. Then season: smoked meat, a pinch of sugar, pepper vinegar, or hot sauce. A pint is a practical side for two to four people. A quart is a lot of cooked greens for one meal, which is why many canners prefer pints even though quarts are allowed.
Frequently asked questions
Can I raw-pack collard greens? No. The tested process is hot pack only, after steaming until wilted.
Do I have to add salt? No. Salt is optional and is not part of the preservation.
My grandmother canned greens in a water bath for years. Why not? Boiling water does not kill botulinum spores. Illness is uncommon enough that unsafe batches sometimes get eaten, and severe enough that one bad jar matters. Current USDA guidance does not allow a water bath for greens.
The jars lost liquid but sealed. Are they ruined? Not automatically. If half or more of the food is still covered and the process was correct, use them first. If most of the liquid is gone, refrigerate and use within a few days.
Can I can the leftover cooking liquid from Sunday greens? Only if those greens were plain, steamed, and packed in fresh boiling water under the process above. Potlikker cooked with meat is a different product and is not covered by this process.