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Preserving Sweet Memories
There’s something incredibly nostalgic about rhubarb for me. On my homestead, rhubarb grows in abundance, tucked into a sunny corner where it thrives without much fuss. The patch came from my father-in-law, who had cultivated it for over 50 years. Now that he’s gone, I think of him every time I harvest it. Preserving rhubarb pie filling is my way of keeping that memory alive—and ensuring I can enjoy this tart, tangy treat all year long.
In this post, I’m going to walk you through a tested, safe method for canning rhubarb pie filling, adapted from the Washington State University Extension’s guidelines. It’s tart, a little sweet, and thickened with Clear Jel®, the safest thickener for canning. I’ll cover substitutions, safety notes, and walk you through the whole process—from garden to jar.
Why This Is a Tested Recipe You Can Trust
This recipe is based on a scientifically tested method from Washington State University Extension. While there’s room to play with some of the ingredients (like sugar and spices), certain parts are non-negotiable for safety:
Use bottled lemon juice (not fresh). You can add more for tartness, but you can’t reduce it. Why Bottled Lemon Juice?
Use only “cook-type” Clear Jel®. Don’t use cornstarch, flour, or other thickeners.
You may reduce the amount of Clear Jel® to make the filling less thick, but not increase it.
Sugar can be increased, reduced, or swapped for maple syrup or honey. Just know lower sugar content may result in a softer set.
Spices and extracts can be changed to suit your tastes. Think cinnamon, ginger, nutmeg, or even cardamom.
Why Use Clear Jel® for Rhubarb Pie Filling?
Clear Jel® is a modified cornstarch specifically designed for canning. Unlike regular cornstarch or flour, Clear Jel® won’t break down during processing or baking. This ensures your rhubarb pie filling maintains a perfect, glossy consistency every time. A runny pie filling can spoil the perfect pie, but Clear Jel® guarantees a consistent thickness that’s ideal for preserving.
Important: Make sure you buy “regular” Clear Jel®, not “instant,” which doesn’t hold up to heat processing. You won’t typically find Clear Jel® in grocery stores, but it’s easily available online. Here are a few reliable sources:
| Online Retailer | Website | Phone Number |
|---|---|---|
| Sweet Celebrations | www.sweetc.com | 1-800-328-6722 |
| Kitchen Krafts | www.kitchenkrafts.com | 1-800-776-0575 |
| The Ingredient Store | www.theingredientstore.com | 1-610-715-3501 |
Remember, 1 pound of Clear Jel® equals approximately 3 cups.
Ingredients for Rhubarb Pie Filling
| Ingredient | 1 Quart | 7 Quarts |
| Rhubarb, sliced | 3 ½ cups | 6 quarts |
| Granulated sugar | 1 cup | 7 cups |
| Regular Clear Jel® | ¼ cup + 1 tbsp | 2 cups + 3 tbsp |
| Cold water | ¾ cup | 5 ¼ cups |
| Bottled lemon juice | ¼ cup | 1 ¾ cups |
| Cinnamon (optional) | ⅛ tsp | 1 tsp |
| Almond extract (optional) | ⅛ tsp | 1 tsp |
Prepare Your Jars and Equipment
Before you begin, make sure your canning jars are thoroughly washed in hot, soapy water and rinsed well. I like to place them in my canner with hot water to keep them warm while I prep the filling. Lids and rings should be prepped according to the manufacturer’s directions—some brands no longer require boiling, so double-check your packaging.
Starting with clean, sanitized equipment is non-negotiable when it comes to safe food preservation. Don’t skip this step!
Step 1: Prep the Rhubarb
Wash and trim the rhubarb stalks, cutting off both the tops and bottoms. Be sure to remove every bit of the leaves—they’re toxic and not safe for consumption. If you’re harvesting in spring, the stalks are usually tender enough to leave as is. Later in the season, you might choose to peel tougher stalks to avoid a stringy texture in your finished filling.
Chop into pieces about ½ to 1 inch in length. If you want to keep that vivid pink color, you can soak the rhubarb in a solution of 1 teaspoon ascorbic acid (or six crushed 500 mg vitamin C tablets) per gallon of water. This helps prevent browning, but to be honest—I usually skip this step, and the filling still turns out beautifully.
Step 2: Macerate the Rhubarb
Place your chopped rhubarb in a large bowl and stir in all of the sugar. Let this mixture sit for at least an hour (or overnight in the fridge). During this time, the sugar draws out the natural juices from the rhubarb, creating a sweet-tart syrup that forms the base of the pie filling.
Step 3: Mix Clear Jel® with Cold Water
In a separate bowl, mix the Clear Jel® with cold water—not warm, and definitely not hot. This part is important: adding Clear Jel® to warm liquid will make it clump instantly, and you won’t be able to save it. Using cold water ensures it dissolves completely and thickens properly when heated.
Step 4: Cook and Thicken the Filling
Pour the macerated rhubarb and its syrup into a large, heavy-bottomed pot. Gently heat the mixture over medium heat until it’s warm and just starting to simmer.
Once warmed through, stir in the Clear Jel® + water mixture. Cook over medium-high heat, stirring constantly. As it thickens and begins to bubble, this is your moment to add in any spices or extracts you’re using—think cinnamon, nutmeg, ginger, cardamom, or even a splash of almond or vanilla extract. This step is your chance to make it your own!
After the mixture starts bubbling, add the bottled lemon juice and boil for one full minute, stirring the entire time.
Why Use Bottled Lemon Juice?
When it comes to canning, bottled lemon juice is essential. It provides a reliable, consistent level of acidity that fresh lemons just can’t guarantee. That acidity is what ensures your pie filling is safe for long-term storage. So please—don’t swap it out!
Step 5: Fill and Process Your Jars
Quickly ladle the hot rhubarb pie filling into your warm, prepared jars, leaving 1 inch of headspace. The mixture will be thick, so take a minute to de-bubble each jar using a spatula or bubble remover. Wipe the rims clean with a damp cloth to remove any drips or residue.
Place the lids on the jars and screw on the bands fingertip tight—not too tight, just snug.
Gently lower the jars into your boiling water canner. Make sure the water covers the tops of the jars by at least 1 inch. Cover the canner and process according to your altitude:
Water Bath Canning Times:
| Altitude | Time for Pints or Quarts |
|---|---|
| 0–1,000 ft | 30 minutes |
| 1,001–3,000 ft | 35 minutes |
| 3,001–6,000 ft | 40 minutes |
After processing is completed, remove jars from the canner with a jar lifter and place them on a towel rack. Do not re-tighten screw bands. Air-cool jars 12 to 24 hours. Remove screw bands and check lid seals. A jar is sealed if the center of the lid is indented or concave.
Storage and Shelf Life
Clearly label jars with the date and contents, then store them in a cool, dark place. Properly sealed and processed rhubarb pie filling maintains its best quality when used within one year.
Enjoying Your Rhubarb Pie Filling
Every time I make rhubarb pie filling, I feel a sense of connection—to the land, to the seasons, and to the people I’ve loved. This recipe not only celebrates spring’s early bounty but also preserves it in the most delicious way possible.
So if you’re like me, with rhubarb growing in abundance on your homestead, now’s the time to preserve it for the cooler months ahead. Trust me, nothing beats the taste of a homemade rhubarb pie in the dead of winter. This homemade rhubarb pie filling is incredibly versatile and perfect for pies, crisps, cobblers, or as a delightful topping for ice cream and desserts.
Love Rhubarb? Here’s More Inspiration from OUr Kitchen
Be sure to check out some of my other rhubarb posts. These recipes and tips will help you use up every last stalk:
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