Canning Strawberry Rhubarb Pie Filling

Strawberry rhubarb pie filling can be canned in a boiling-water bath because both fruits are high-acid. There is no USDA recipe titled exactly “strawberry rhubarb pie filling,” which is why published methods split into two groups: a Ball/Bernardin-style filling thickened with apples (no starch, 15-minute process for pints) and a ClearJel filling adapted from tested USDA cherry or berry pie fillings (30-minute process for pints or quarts).

Both approaches work if you follow the rules that actually affect safety: bottled lemon juice in the ClearJel version, cook-type ClearJel only (never cornstarch, flour, tapioca, or instant ClearJel), correct headspace, and altitude-adjusted processing time. The rest of this article shows how to choose a method, make the filling, avoid siphoning, and turn a jar into pie later.

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Why Online Recipes Conflict

Home canners run into three different products sold as “pie filling”:

A fruit-and-apple preserve from Ball and Bernardin. Apples add pectin and body. No modified starch. Processed like many fruit conserves: 15 minutes for pint jars.
A ClearJel pie filling modeled on USDA apple, blueberry, cherry, and peach fillings. The starch stays pourable while hot so heat can move through the jar, then sets as it cools. Processed 30 minutes for pints or quarts.
Unthickened or cornstarch recipes copied from freezer methods or old cookbooks. Regular cornstarch and flour break down in acid and heat, can pack the jar too densely for reliable heat penetration, and often go watery in storage. Extension guidance is not to substitute them for ClearJel in canned pie filling.

If the goal is a jar that opens like commercial pie filling, use cook-type ClearJel. If you cannot find ClearJel and still want a tested published formula, use the Ball-style apple version and thicken at baking time if needed.

What You Need Before You Start

Equipment

Water-bath or atmospheric steam canner
Pint or quart canning jars (Ball-style recipe is tested for pints; ClearJel adaptations follow USDA pie-filling times for pints and quarts)
New lids, rings, funnel, bubble remover, jar lifter
Wide, heavy pot (ClearJel scorches in a thin pan)

Ingredients that are not optional

Cook-type ClearJel (also labeled regular ClearJel) if you use the thickened method. Instant ClearJel thickens in cold liquid and is not approved for canning pie filling.
Bottled lemon juice in any ClearJel recipe. Fresh lemon juice varies in acidity. Do not reduce the amount; it supports acidity and storage stability.
Rhubarb stalks only. Leaves contain high levels of oxalic acid and are discarded, never canned.

ClearJel buying note: One pound is about 3 cups. A 7-quart batch of berry-style filling uses roughly 1¾ to 2¼ cups depending on the fruit formula.

How to Choose and Prep the Fruit

Use firm, tart rhubarb and ripe but not collapsing strawberries. Green or pale rhubarb is usable; red stalks look better in the jar. Trim woody ends. Cut stalks into ½- to 1-inch pieces.

Hull strawberries and halve or quarter large berries so pieces match the rhubarb.

Frozen fruit works. Use unsweetened fruit. Thaw just until pieces separate, keep the juice, and use that juice as part of the water in a ClearJel recipe. Frozen fruit has already lost some air, which slightly reduces siphoning. Fresh strawberries hold a lot of air and are the usual reason jars weep in the canner. Extension staff who adapt cherry or berry pie filling for this mix often precook the rhubarb and briefly heat or blanch the berries for that reason.

Method 1: Ball-Style Strawberry Rhubarb Filling (No ClearJel)

This is the published Ball/Bernardin approach: rhubarb, strawberries, cooking apples, sugar, and orange. Apples supply body so you do not need starch in the jar. Healthy Canning and multiple home-preserving reprints match this formula.

Yield: about 5 pint (500 ml) jars Headspace: 1 inch (2.5 cm) Process: 15 minutes in a boiling-water or steam canner at 0–1,000 ft (see altitude table below) Jar size: pints. There is no widely published tested time for quarts of this exact recipe.

Ingredients

7 cups rhubarb, cut into 1-inch pieces (about 1¾ lb / 750 g)
3 large cooking apples, peeled, cored, and finely chopped (about 1½ lb / 750 g before prep)
2 cups granulated sugar
1 tablespoon orange zest
¼ cup orange juice
4 cups hulled, halved strawberries

Steps

Heat jars in the canner. Keep them hot.
Combine apples, zest, juice, rhubarb, and sugar in a large stainless-steel pot. Bring to a boil, stirring so the sugar does not scorch. There will be little liquid at first; the fruit releases juice as it heats.
Reduce heat and boil gently 10–15 minutes, until the rhubarb is tender but not mush.
Stir in strawberries. Return to a boil. Remove from heat.
Ladle hot filling into hot pint jars, 1-inch headspace. Debubble. Adjust headspace. Wipe rims. Apply lids fingertip-tight.
Process 15 minutes at 0–1,000 ft after the water returns to a full boil. Turn off heat, wait 5 minutes, then remove jars. Cool 12–24 hours. Check seals.

What to expect: A spoonable fruit conserve, not a glossy commercial gel. For a tighter pie slice, stir 1–2 tablespoons of cornstarch or ClearJel slurry into the opened jar on the stove before filling the crust, or bake a bit longer so juices reduce.

Do not add ClearJel or cornstarch to this formula and then use the 15-minute time. Thickener changes heat penetration.

Method 2: ClearJel Filling Adapted From USDA Berry or Cherry Pie Filling

Oregon and Washington Extension staff have directed canners to use the USDA cherry or berry pie-filling formula and replace the named fruit with a mix of strawberry and rhubarb, keeping the ClearJel and bottled lemon juice unchanged. Both fruits are high-acid, which is why water-bath processing stays appropriate.

The blueberry (berry) formula is a practical starting point because strawberries behave more like berries than like cherries.

Per 1 quart jar (one 9-inch pie)

3½ cups prepared fruit (a good split is about 2 cups rhubarb + 1½ cups strawberries, or half and half)
¾ cup plus 2 tablespoons sugar
¼ cup plus 1 tablespoon cook-type ClearJel
1 cup cold water or fruit juice
3½ teaspoons bottled lemon juice

For a 7-quart canner load

6 quarts prepared fruit
6 cups sugar
2¼ cups cook-type ClearJel
7 cups cold water or juice
½ cup bottled lemon juice

Sugar can be adjusted to taste. Lemon juice and ClearJel should not be cut. Optional: a pinch of cinnamon or a few drops of vanilla after the lemon juice boil; do not add extra starch.

Steps

Wash and cut fruit. Briefly cook rhubarb in a small amount of water until it just starts to soften (or blanch in boiling water 1 minute, as USDA pie-filling recipes do for firmer fruit). Drain, keep hot. Heat strawberries only until warm so they do not collapse. Keep any juice.
In a separate wide pot, whisk sugar and ClearJel together while dry. That prevents lumps. Whisk in the cold water or juice.
Cook over medium-high heat, stirring constantly, until the mixture thickens and bubbles. It can go from thin to paste in less than a minute.
Add bottled lemon juice. Boil 1 minute, stirring.
Fold in the hot fruit. If the mix is so stiff it will not ladle, stir in a splash of hot water or juice. Over-thick filling is a common cause of siphoning and underprocessed centers.
Fill hot jars at once. Leave 1 to 1¼ inches headspace (some pie fillings do better at 1½ inches). Debubble thoroughly; thick filling hides pockets of air.
Wipe rims well. Sticky rims are a leading cause of failed seals.
Process immediately in a boiling-water canner:

Altitude	Pints or quarts
0–1,000 ft	30 minutes
1,001–3,000 ft	35 minutes
3,001–6,000 ft	40 minutes
Above 6,000 ft	45 minutes

These times match USDA blueberry and cherry pie filling.

When time is up, turn off the heat. Leave jars in the canner 5–10 minutes before lifting them out. Pie filling is notorious for siphoning if it hits cool air while still violently hot.

Cool undisturbed 12–24 hours. Sealed lids stay down when pressed. Unsealed jars go in the refrigerator and should be used within a few days or frozen.

How to Cut Down Siphoning

Siphoning (filling that weeps under the lid during processing) is the most common complaint with canned pie filling. The jar can still be safe if it seals and the rim is clean, but loss of liquid leaves fruit high and dry.

Practical controls:

Blanch or preheat the fruit so trapped air leaves before the jar is sealed.
Leave extra headspace: 1¼ inches is often more reliable than a tight 1 inch.
Debubble. Run a spatula around the inside several times.
Do not overdo ClearJel. Wisconsin work summarized by WSU notes that using about three-quarters of the listed ClearJel still makes an acceptable filling that weeps less.
Keep filling and jars hot. Delays let the starch set in the pot.
Rest jars in the canner 5–10 minutes after processing before you move them.

If a sealed jar lost a little liquid, wash the outside, dry it, and store it. Use those jars first. If the seal failed or food is on the sealing surface, refrigerate.

How to Use a Jar

One quart is the usual amount for an 8- or 9-inch pie. One pint is enough for a small pie, hand pies, or a crisp for two.

Open the jar, taste, and adjust. Canned filling is already cooked. Pour it into an unbaked crust and bake until the crust is done and the filling is bubbling in the center (often 40–50 minutes at 375–400°F / 190–200°C). If Method 1 filling looks loose, thicken it on the stove first.

Other uses that do not need a full pie:

Spoon over cheesecake, yogurt, or ice cream
Fold into muffin or coffee-cake batter
Use as the fruit layer in bars or a dump cake
Warm and serve with biscuits or shortcake

Best quality is within a year. Sealed high-acid fruit is considered safe longer if the lid stays vacuum-sealed and the food looks and smells normal, but color and texture fade. Store in a cool, dark place. After opening, refrigerate and use within several days.

Mistakes That Ruin Jars or Texture

Using the wrong starch. Cornstarch, flour, tapioca, and instant ClearJel are not substitutes in a canned pie filling. Cook-type ClearJel is the thickener used in USDA pie-filling research.

Cutting the lemon juice. In ClearJel recipes the listed bottled lemon juice is a safety and stability ingredient, not only flavor.

Canning quarts of the Ball apple recipe on a 15-minute schedule. That formula is published for pint jars. If you want quarts of a gelled filling, use the ClearJel method and the 30-minute pie-filling times.

Filling jars too full. Pie filling expands. Tight headspace pushes product under the lid.

Cooking the fruit to mush before it goes in the jar. Rhubarb falls apart with long boiling. Soften it, then stop. It cooks again in the canner and again in the oven.

Guessing at altitude. Ten extra minutes at high elevation is not optional. Water boils cooler as elevation rises, so the process time has to increase.

Leaving rings cranked down in storage. After 24 hours, remove rings, wash jars, and store without rings so rust and false seals are easier to spot.

If You Would Rather Not Water-Bath It

A freezer filling is simpler and can use cornstarch. Cool the cooked filling, pack into freezer containers with headspace for expansion, and freeze up to a year. Ball publishes a separate strawberry-rhubarb freezer filling that is not a canning recipe. Do not put a cornstarch freezer formula through a canner and call it shelf-stable.

You can also can plain stewed rhubarb (USDA: sugar plus rhubarb, ½-inch headspace, 15 minutes) and keep frozen strawberries. Combine them when you bake. That avoids the thickener problem entirely.

Frequently Asked Questions

Is there an official USDA strawberry rhubarb pie filling? No titled recipe. The accepted paths are the Ball/Bernardin apple-rhubarb-strawberry preserve and an Extension-supported swap of strawberry and rhubarb into USDA cherry or berry pie filling with ClearJel and bottled lemon juice left as written.

Can I use honey or less sugar? Sugar in these recipes is mostly for flavor and texture, not for safety of high-acid fruit. You can reduce sugar in the ClearJel version, but the gel may be softer. Do not replace lemon juice with more sugar or honey.

Can I skip ClearJel and thicken when I bake? Yes. Can a tested unthickened fruit mixture (the Ball-style recipe, or plain canned rhubarb plus separately preserved strawberries) and add starch at pie time. That is often the cleanest option if ClearJel is hard to find.

Why did my filling turn thin after canning? Wrong starch, too little ClearJel, or fruit that released a lot of extra juice. Cornstarch often looks thick in the pot and thin in the pantry. Cook-type ClearJel should set as the jars cool; it will look looser while piping hot.

Why is there foam or fruit floating at the top? Strawberries trap air. Blanching or using frozen fruit helps. Floating fruit in a sealed, properly processed jar is a quality issue, not automatically a safety failure.

Do I need a pressure canner? Not for these high-acid fruit fillings when you follow a tested-style recipe. Pressure canning is for low-acid foods. Using a pressure canner on a water-bath recipe without a tested pressure time is not an upgrade.

How do I know a jar failed? Lid flexes, leaks, spurts when opened, unusual odor, mold, or fizzing. Discard those jars. Do not taste.

Canning strawberry rhubarb pie filling is worthwhile when the fruit is abundant and you want pie in January without starting from scratch. Pick one tested-style method, measure the lemon juice and thickener as written, give the jars enough headspace, and process for your altitude. The jar on the shelf should taste like late spring, not like a guessing game.