Plum butter for canning is a slow-cooked plum puree sweetened and spiced until it mounds on a spoon, then packed hot into jars and processed in a boiling-water canner. Plums are a high-acid fruit, so a tested fruit-butter method does not need a pressure canner. The spread keeps on the shelf when the pulp is cooked thick, the jars are filled correctly, and the processing time matches your elevation.
The texture is the point of the recipe. Jam is cooked to a gel and often still has pieces of fruit. Butter is milled or blended smooth and cooked longer so water evaporates and the puree becomes dense enough to spread. Sugar and spices shape the flavor. They do not replace correct acidity, headspace, or processing time.
What you need before you start
Use ripe plums with no mold or serious bruising. Italian prune plums, Damsons, and other freestone or cling varieties all work. Flavor and moisture vary by type, so measure the finished pulp rather than relying on a fixed whole-fruit weight. Yield is hard to predict because juicier plums lose more volume as they reduce.
Oregon State University Extension’s basic fruit-butter formula, which lists plums as a suitable fruit, uses:
- 2 quarts plum pulp
- 4 cups sugar (about ½ cup sugar per cup of pulp; the acceptable range is ¼ to ½ cup per cup)
- 2 teaspoons ground cinnamon
- Optional spices to taste, such as allspice, cloves, or ginger
Start spices low. A practical range is about 1 teaspoon cinnamon per quart of pulp and about ¼ teaspoon of any stronger spice. Lemon or orange zest, a small amount of citrus juice, or ½ to 1 teaspoon vanilla can be added for flavor. Brown sugar can replace part of the white sugar. Up to 1 cup of honey can replace about 3 cups of sugar if you want a lower-sugar batch, but the butter will be less sweet and may take longer to thicken.
Equipment that matters: a heavy, wide pot (an 8- to 10-quart kettle with a broad bottom scorches less than a thin, narrow pan), a food mill or sieve, a boiling-water canner with a rack, half-pint or pint jars, new two-piece lids, a jar lifter, a funnel, and a headspace tool. A slow cooker is optional for the long reduction.
Do not use this method for butters made from Asian pears, figs, pumpkin, melon, or mango. Extension guidance states there are no research-based home-canning processes for those butters. Refrigerate or freeze them instead.
Turn plums into pulp
Wash the fruit. Halve it and remove the pits before cooking. Plum pits are large, and leaving them in makes crushing and milling harder. A few fragments can still be caught by the food mill.
Crush the plums and cook them in their own juice, stirring often, until soft. A splash of water is only needed if the fruit is dry and threatens to stick before the juice runs. Prunes, if you start with dried fruit, need about one-quarter as much water or juice as fruit.
When the plums are tender, press them through a food mill, cone strainer, or sieve. This step removes skins and any remaining pit pieces and gives the smooth texture that defines butter. If you want skins in the spread, blend the cooked fruit instead, then check carefully for pit fragments. Measure 2 quarts of pulp before adding sugar.
Cook until it is actually butter
Heat the pulp and sugar slowly until the sugar dissolves, then boil, stirring often. Fruit butter scorches easily once it thickens. A wide pan reduces faster than a tall one. Small batches are easier to control than one very large pot.
Three cooking options all work if the doneness test is the same:
- Stovetop in a heavy kettle, stirred frequently.
- Oven at about 275°F in a shallow pan, stirred so a skin does not form.
- Slow cooker on low for roughly 8 to 10 hours with the lid ajar so steam can escape, stirred now and then. Most of the thickening happens late.
Stop when the butter rounds slightly on a spoon and looks glossy. A second check: chill a plate, spoon a little butter onto it, and look for a mound that holds its shape with no ring of liquid separating around the edge. Undercooked butter will separate in the jar. Overcooked butter becomes pasty and can scorch at the edges.
Keep the finished butter hot while you fill jars.
Pack and process the jars
Wash jars and keep them hot. Lids should be prepared according to the manufacturer’s directions. Current guidance does not require pre-sterilizing jars when the boiling-water process is 10 minutes or longer.
Ladle hot butter into hot half-pint or pint jars, leaving ¼ inch of headspace. Remove air bubbles, recheck the headspace, and wipe the rims with a clean damp cloth. Any smear of butter on the rim can keep the lid from sealing. Apply lids and screw bands on fingertip-tight.
Place jars on the rack in a boiling-water canner. Water should cover the lids by 1 to 2 inches. Bring the water to a full rolling boil, then start the timer. Process half-pints and pints for the time in the table below. Oregon State University Extension specifies 10 minutes for fruit butters at the base elevation, with added time at higher elevations. Do not use quart jars for this spread. The tested fruit-butter processes are written for half-pints and pints.
| Elevation | Processing time (half-pints or pints) |
|---|---|
| 0–1,000 ft | 10 minutes |
| 1,001–3,000 ft | 15 minutes |
| 3,001–6,000 ft | 20 minutes |
| 6,001–8,000 ft | 25 minutes |
| 8,001–10,000 ft | 30 minutes |
When the time ends, turn off the heat, remove the canner lid, and wait 5 minutes before lifting out the jars. Set them on a towel with space between them. Leave them undisturbed for 12 to 24 hours. A sealed lid is firm and does not flex when pressed. Refrigerate any jar that did not seal and use it within a few weeks. Remove rings from sealed jars, wipe the jars, label them, and store them in a cool, dark, dry place. Quality is best within a year. Refrigerate after opening.
If you cut the sugar far below the ¼-cup-per-cup range, do not assume the standard 10-minute process still fits. The National Center for Home Food Preservation uses 15 minutes at 0–1,000 feet (20 minutes at 1,001–6,000 feet, 25 minutes above 6,000 feet) for its reduced-sugar apple butter, because less sugar changes how the product heats. A very low-sugar plum butter is safer frozen, or made only if you follow a tested reduced-sugar fruit-butter process.
Problems that show up after canning
Liquid separating in the jar. The butter was not cooked long enough. The plate test is more reliable than the clock, because plum moisture varies.
Dark layer or scorched taste. Heat was too high or stirring stopped once the puree thickened. A heavy pan and lower heat after the sugar dissolves prevent this.
Unsealed lids. Usually a sticky rim, a chip in the jar, or bands tightened too hard. Wipe rims after filling, and stop at fingertip-tight.
Butter too stiff to spread. It was reduced too far. Warm a spoonful slightly, or stir in a teaspoon of water or juice per serving. Next batch, stop at the mound-and-sheen stage.
Weak plum flavor. Overripe fruit can taste flat, and too much clove or allspice covers the fruit. Cinnamon alone is enough for many batches.
How to use it
Plum butter is a spread for toast, biscuits, and cheese boards. It also works as a glaze for pork or chicken near the end of cooking, stirred into oatmeal, or layered in a plain cake. Because it is already reduced, a small spoonful goes further than jam.
Frequently asked questions
Can plum butter be canned without sugar? Plums are high-acid, so sugar is not the safety control the way acid is in tomatoes. A long-boil unsweetened puree can be thick, but it is not the same product as the tested sweetened butter, and low-sugar spreads need a longer process. For pantry storage, stay inside a tested sugar range or use the longer reduced-sugar fruit-butter time. Freezing is the simple option if you want little or no sugar.
Do the skins have to come out? No. Milling them out gives the classic smooth butter. Blending them in is fine if pits are removed and you like a slightly coarser spread. Skins also carry much of the color.
Is a steam canner acceptable? Atmospheric steam canners can be used for the same products and times as a boiling-water canner when the manufacturer and your extension guidance allow it, jars are processed the full adjusted time, and the canner stays in the steam range for the whole process. A pressure canner is not required for this high-acid butter.
How many plums make 2 quarts of pulp? There is no single number. Juiciness, pit size, and how far you cook the fruit all change the yield. Cook and mill first, then measure the pulp and scale the sugar to that volume.