How to Make Oven-Roasted Strawberry and Rosemary Jam (and grow the strawberries)

Summer. In. A. Jar. The local strawberry season is too short for many of us; just six weeks. Have you ever wanted to capture the smell and flavor of a just-picked, warm, lusciously ripe strawberry? If so, try making a jar of this oven-roasted strawberry and rosemary jam with a touch of lemon juice or balsamic vinegar. This recipe was given to me by my friend, Malinda Hersch, Program Director at The Nashville Food Project and it is easy to make.

Malinda made this jam three years ago, packaged in half-pint mason jars, for TNFP’s deluxe gift baskets prepared for attendees of the Nourish Patron’s Party held annually at the legendary Bluebird CafeInspired by Malinda’s gift, I have been making my own small batch of this jam every year since, as soon as the venerable Tennessee strawberries come in. Nourish is a Nashville fundraiser which brings together the South’s most innovative chefs for an evening of delicious food and wine.

The idea for this post started last week when I read in Edible Nashville, a gorgeous publication on local food trends, for which I am a contributing writer on gardening, that the first Tennessee strawberries were starting to come in. On a whim, I emailed Hank Delvin at Delvin Farms at 7:00 A.M. to tell him I had this fabulous recipe for roasted strawberry jam I wanted to make and by-the-way, I was looking for ripe strawberries. He said they were getting ready to pick that morning and invited me to come along.

I love driving out to Delvin Farms in College Grove, Tennessee. It’s a beautiful drive, and I know I’ll always learn something new about botany and organic growing practices from Hank, and his dad, if he’s around. Check out this post from last year when I chronicled a morning spent gleaning vegetables for TNFP at Delvin Farms. The most interesting tidbit I learned on my most recent trip was the concept of incomplete pollination. Like for many of you, I’ve seen the results of incomplete pollination, misshapen berries like the ones in the picture below, I just didn’t know there was a name or reason for it.

By the way, misshapen isn’t alway ugly. Look at this amazing strawberry I found in the field. My friend, Roberta, said it looks like an angel. Indeed.

Hank plants new June-bearing strawberry plants in long rows of plastic-covered raised beds every September. The plastic keeps the weeds out, since, as an organic farm, they do not use chemical weed-killers.

The plants go dormant in the winter and start growing again in the spring. Once the delicate flowers start blooming, it is imperative that the tender blooms be protected from frost.

To this end, whenever the temperature dips, Hank’s staff has to cover the rows of strawberries with agricultural cloth. This past spring there were six such touches of frost in the three weeks preceding their first harvest.

Strawberries are considered self-pollinators, and as such, their male and female parts are on the same flower. It takes gravity, the wind, rain, and some insect pollinators to move the pollen across the flower to pollinate it. If the plants are covered, the wind and bees can’t do their part.

I was amazed to see the plants’ leaves waving in the wind, a wind I couldn’t even feel.

Pistils and stamens. Remember them?

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The strawberry flower is not your typical flower. Yes, it has the male parts which are the yellow pollen coated anthers known as stamens. And it has the female part called an ovule that connects to an ovary and collectively is known as the pistil. However, whereas most flowers only have one pistil, the strawberry is an aggregate fruit and, as such, has as many as 500 spike-like ovules, each one an immature egg needing to be pollinated so it can produce seed. The more of those ovules that get pollinated, the bigger, puffier, and more perfect the strawberry.

The Recipe!

Yield: 4 cups of jam

8 cups (2 quarts) strawberries, stems removed and berries quartered
4 cups granulated sugar
¼ cup lemon juice or balsamic vinegar
4 bushy sprigs fresh rosemary (1/2 ounce).

Clean and hull two quarts of strawberries. Figure on four cups of berries in each quart container.
DSC_0471 (1)

Slice berries into lengthwise quarters.

Add strawberries and sugar to a mixing bowl, stir and allow to macerate, which means to break down and soften.

Allow berries to macerate for two hours, or up to 24 hours, stirring regularly to re-incorporate the sugar that sinks to the bottom of the bowl into the mixture. Don’t skip this step. It’s what helps the berry chunks keep their shape.

Squeeze the juice out from one large lemon and set aside.

Pour the macerated strawberries and the lemon juice into a large saucepan. Bring to a rolling boil over high heat. Be careful not to let the juice boil over.
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Once the mixture reaches a full boil, reduce the heat and continue cooking, uncovered, for ten minutes. About five minutes into the cooking time, add the rosemary sprigs to the pot, stir, and continue to cook.

Cooking the berries and sugar together helps release the naturally occurring pectin from the strawberries. Pectin is a gum-like substance that is needed to “set” jams and jellies. It occurs naturally in fruits, but more can be added in the form of powder if a faster set is desired. Adding an acid, such as lemon juice or vinegar, helps fruit release its natural pectin. For more on pectin, read my post about making grape jelly.

Now it is time to roast the berries.
Preheat oven to 150º. If your oven’s lowest temperature setting is a little higher than that, that is fine. You could even set the oven to convection roast and cook it in half the time, but I prefer the slow cook method.

Pour the mixture, including the rosemary, into a  13″ by 18″ baking pan. Place pan on the middle oven shelf and roast for 10 hours, or until the syrup is thickened and has a gel-like appearance. I often put it in the oven at bedtime and take it out the next morning.

How to test hot jelly for gel formation: Use a chilled wooden spoon to scoop up some jam. Allow jam to cool and then tilt the spoon, so jam drips off. If the drips form a triangle-shaped thick flake, it is ready. Don’t get too hung up here with the testing. After 10 hours, assume it is going to be great!

Ladle into four 8-ounce hot, clean jars using a large-holed funnel and either
1) process in a water bath for 10 minutes, using the appropriate two-part jar caps, aka “canning,” or
2) cover with lids, let cool, and store in the refrigerator until ready to use, or
3) freeze in plastic containers.

I love the combination of strawberries, a little sugar, and balsamic vinegar, so I often substitute four tablespoons of balsamic vinegar for the lemon juice. The balsamic vinegar not only flavors the jam, but it also gives it a smoother, earthier taste than the lemon juice.

I love this jam spooned over @judyschickens granola and served with homemade plain, low-fat yogurt.

About The Nashville Food Project

The Nashville Food Project brings people together to grow, cook and share nourishing food, with the goals of cultivating community and alleviating hunger in our city. Their primary fundraising event, Nourish, will take place on Thursday, July 20th this year in the gorgeous dining hall at Montgomery Bell Academy.

Other Recipes with Strawberries
Strawberry Rhubarb Pie
Very Berry Clafoutis

Other Jelly Recipes
Crabapple Jelly
Grape Jelly

Other Breakfast Foods
DIY Yogurt and Yogurt Cheese
Sorghum, Oats, and Cranberry Granola
The Biscuit King
Mom’s Monkey Bread, circa 1970

A note to readers:
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© 2017 Judy Wright. All rights reserved. Photos and text may only be used with written consent.

23 thoughts on “How to Make Oven-Roasted Strawberry and Rosemary Jam (and grow the strawberries)

  1. Judy
    I love getting your blog! It was great to see you and Kelly in Richmond. Hope to see you next year .


    Carolyn M. Osteen
    Retired Partner

  2. This sounds heavenly! Must try. I used to pick strawberries in the back yard at 2300 Hampton where my grandfather, W.A. Bass, had a big garden. A tedious job but to my mind there’s nothing better than TN strawberries. The Strawberry Festival in Plant City, FL, could not match them. Ditto Fl tomatoes v. TN tomatoes. I guess TN just has better dirt!

    1. Jeannie, it must be our good dirt! Family dirt! I have to admit, I have not been fond of the large strawberries coming out of Florida. Bigger isn’t better in terms of flavor. And tomatoes. There’s nothing like a Cherokee Purple grown in TN! Hope youget back home to enjoy some. Judy

  3. Hi Judy: Am so happy to get my first edition of your blog, and I must compliment you. Your writing is very friendly and clear! Strawberries Re starting to come in here in Savannah, and I am excited to try your recipe. For the refrigerated version) On a different note, I found your cute sweater cover, but don’t see your top that I loved so much. Could your sister help me find it? Maybe it’s not a current item? Anyway….it was a delightful weekend. You had to leave and miss Hollywood Cemetary. Catch it when you go to Williamsburg. It is splendid. Fondly, Annie Moncure

    Sent from my iPhone


  4. Hi, I met you at AZ Kelley when you came to share your chicken. (I’m across the hall from Grace). Love this strawberry jam recipe. I am definitely going to have to try it this year……maybe this weekend.

    Thanks, Patricia Murcray


    1. Thanks for writing, Patricia! Yes, I remember you. I loved my visit to AZ Kelley and have been singing the school’s praises all over Nashville. I hope you get a chance to try making the jam. It’s very gratifying to make something so tasty that can be enjoyed for months to come. I just made another small batch of jam with the balsamic vinegar. Thanks for writing! Judy

  5. Strawberry season is weeks away here in MA, but that’s good because this week of rain would destroy the crop! Judy, thanks for asking about an email subscription option on Comptonia – I didn’t realize there wasn’t one, but I added it in the sidebar today. Please let me know if it works 🙂

    1. Definitely do the balsamic. It is so good. I give everyone that comes over a spoonful so we can all gush together. My next strawberry food will be a strawberry cake. Do you have a good recipe for that? Enjoy your strawberries!

    1. I love Nigela, too! Have a nice weekend, Kat and thanks for the shout out!! PS, when there’s not much else to make for lunch in the fridge, there’s always the strawberry jam and almond butter for a nice PB&J sandwich. My fave!

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