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Giant tomatoes from 20-year-old seed? Yep.

Dig In video series: Save extra seeds for next year's garden (and many to come)

Advanced Master Gardener Debbie Courson Smith shows off a giant tomato she grew from seeds she bought 20 years ago. The 24th edition of the Idaho Statesman's Dig In garden video series is on fall planting and seed storage. (Video by Katy Moeller)
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Advanced Master Gardener Debbie Courson Smith shows off a giant tomato she grew from seeds she bought 20 years ago. The 24th edition of the Idaho Statesman's Dig In garden video series is on fall planting and seed storage. (Video by Katy Moeller)

Do you buy new garden seeds every year? I do. Those glossy seed packets with gorgeous photos of flowers and luscious produce are hard to resist.

I also usually toss leftover seeds from the previous year, figuring that new is better. Out with the old, in with the new.

What a waste.

This week I learned from Debbie Courson Smith, a University of Idaho advanced master gardener, that her seed collection — hundreds of seed packets — includes some that are up to 20 years old.

She showed me one of the Mortgage Lifter tomatoes that she grew from seed she bought at Edwards Greenhouse two decades ago.

“They’re not always pretty on top but they’re giant, they can weigh up to 2 pounds each, and they are delicious,” Debbie said.

So those tomato seeds are outliers but they’re also a good reminder that seed life can exceed expectations.

Many but not all vegetable and flower seeds are good for two to three years, and it’s possible to extend seed viability through good storage practices, Oregon State University Extension Service researchers say. They recommend cool and dry conditions (50 degrees with 50 percent humidity).

Seeds that have the shortest life include parsnips, spinach, lettuce and alliums, researchers say. They suspect seeds with the highest oil content degrade the fastest.

Debbie keeps her seed collection in a large plastic box. It’s arranged alphabetically, with name tags, so that she can easily find what she’s looking for. She keeps the box in her closet, which is dark, cool and dry.

Though she has a large collection of vegetable and flower seeds, she can’t resist picking up more when they’re on clearance at the dollar store.

Fall planting

Debbie has been busy with fall planting.

She recommends planting native flower seeds in the fall, including milkweed (only plant that monarch butterfly caterpillars eat), black-eyed Susans, calendula and globe thistle.

“I’ve put these in my landscape, so they will emerge next spring,” she said.

She also planted some vegetables, including kale and Everlasting Spinach.

Katy Moeller: 208-377-6413, @KatyMoeller

Tips for storage, checking viability

▪  How can I ensure seeds stay dry? Place packets in a sealed jar with powdered milk or rice at the bottom to absorb moisture. Store your seed jar in the refrigerator or a cool area, such as a basement.

▪  If they’re old, how can you tell if they’ll germinate? Here’s a germination test: Soak a piece of paper towel in water and spread 10 seeds on the towel. Roll up the towel, put it in a plastic bag and place in warm spot in kitchen. Check for germination two to five days later. The number that germinate in this test is the percentage that you’re expected to see if you plant the seed in the garden (so if five sprout, then you should expect a 50 percent germination rate from the seed).

Source: Oregon State University Extension Service

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