The science and art of canning at home

Posted 8/13/20

Local author Marisa McClellan is an expert at the complicated art of canning. by April Lisante On Mother’s Day, I thought it would be a good idea to plant a garden with my youngest daughter. We …

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The science and art of canning at home

Local author Marisa McClellan is an expert at the complicated art of canning.

by April Lisante

On Mother’s Day, I thought it would be a good idea to plant a garden with my youngest daughter.

We were two months into quarantine at that point, and I’d already painted almost every interior surface of my home, so I thought why not move on to the Great Outdoors? We dug up an 8-by-8 plot of yard and threw down some baby tomato plants, cucumbers, peppers and some herbs.

But as I planted with my daughter in the thick soil, I thought, this is cute, but there’s no way anything is going to grow.

We fenced it, made a little path through the center, and watered it loyally every other day.

It is now mid-August, and the garden is a monstrosity so big, so abundant, it’s taken on a life entirely of its own. Even my daughter is outsized by the vines. We’ve got big tomatoes, rosemary, cilantro, cherry tomatoes, a giant basil and squash blossoms that promise a ton of zucchini. The green peppers are coming up slowly, but surely. I predict we’ll have so many, it’ll be sausage and peppers for a week straight.

This week, I was plotting my picking when I had an idea.

Delirious with DIY and bolstered by the miraculous appearance of the veggies, I decided to go full-on quarantine pioneer with my cornucopia of garden delights.

If you too decided a garden was your project du jour last spring, keep on reading, because this week, I sought out a local pro to explain to me how to use mason jars not as painted farmhouse candle holders, but for the task nature intended: canning.

Marisa McClellan lives here in Philadelphia, but the young mother grew up in Oregon canning everything from applesauce to blackberry jam. She started out as a food blogger and devoted herself to canning full time in 2009. Since then, she has written four books on the subject and is one of the area’s foremost authorities on safely and successfully canning. Her debut book was titled “Food in Jars: Preserving in Small Batches Year-Round.” Her most recent book, published last spring titled “The Food in Jars Kitchen,” goes a step further than canning, and talks about how to use up what you’ve canned when you get fancy making chutneys, relishes and the like.

“Often people make a bunch of jams or pickles and they don’t know what to do with it,” McClellan said.

Canning seems easy, but there are rules. Safety and cleanliness are paramount, she said, and so are reliable recipes. This is not the time to start canning your grandmother’s Sunday gravy, or messing around with ingredients. Safety is critical to avoid bacteria spores.

“Canning is both a science and an art form,” she said. “But there is a lot of science to it. A lot of home cooks like improvising recipes but that is not safe with canning.”

I asked her to explain the process using something we all might have a lot of this month: tomatoes. If you planted some of the big boys, like San Marzanos, and you’re facing a bit of a bumper crop, the process is fairly simple.

Canning is an umbrella term that describes the act of preserving produce. There are two main ways to can, either with a hot water bath for fruits and veggies high in acids like tomatoes, or pressure canning, which requires a pressure canner (around $50 to $150) for those items lower in acidity that need to be canned at a higher temperature. We stuck with the hot pot bath on the stove method.

First, grab brand new, clean mason jars and boil up two pots of water. The first pot should be a big, 12 to 16-quart size, brought to a rolling boil, with a rack inside on the bottom to hold the jars upright. Drop a few empty, lidless quart-size mason jars in this pot. Bring the second smaller pot to a rolling boil. Core the tomatoes and cut an X in the bottoms. Drop them into the second pot and blanche them for about thirty to forty-five seconds, remove and peel away the skins.

Remove a mason jar from the boiling water, drop about two tablespoons of lemon juice in the bottom (to add a little extra acidity) and fill with blanched tomatoes. Pack the tomatoes in using a chopstick or other prod to pack them tightly. Add a bit of boiling water on top of them until the total volume of the jar reaches just half an inch from the top.

“Put the top on, wipe the rim and twist the ring until it meets resistance,” McClellan said.

Then, lower the large pot to a simmer and drop the tomato-filled jar back into the large pot. This step extracts remaining oxygen from the jars. After about ten minutes, remove the jars and allow them to cool off on the counter. Check that the seals are intact, wipe the exterior, label them with the date and store them in a cool dry place, like a basement or closet.

“You don’t want to arrange them on your beautiful open shelving in your kitchen,” McClellan said. “It needs a place out of direct light. It is shelf stable until you break the seal.”

If you have questions about anything, McClellan also details this whole process step-by-step at

And you’ll find that this same method works for acidic fruits like peaches, nectarines and other stone fruits, which will be abundant this month.

“If you have a lot of peaches or are finding peaches right now at the farmer’s market,” McClellan said. “I would advise people to start with recipes from reliable sources, like the Ball mason jars site or my Website.”

Visit or McClellan’s site for additional insight and recipes.