What Makes Heirloom Seeds So Special? Gardening Experts Explain

Heirloom seeds are cherished in the gardening community for their historical significance and role in promoting biodiversity. These seeds are known for their unique characteristics, delicious produce, and rich histories, appealing to both experienced gardeners and beginners.

But what exactly are heirloom seeds? And are they of higher quality than other types of seeds? Ahead, garden experts explain what heirloom seeds are, highlight their benefits, and share where you can find reliable heirloom seeds.

What Are Heirloom Seeds?

Heirloom seeds are seeds from open-pollinated plant varieties that are often over 50 years old and have been passed down through generations for their desirable traits, such as flavor, color, or hardiness. However, Lorin Nielsen, head horticulturist at Epic Gardening, explains that the term heirloom varies widely from one seed company to another. "Some seed companies consider heirloom to be seeds much younger, varieties released 20 to 25 years prior," says Nielsen. "There is no uniformity across seed companies on exactly how old a seed needs to be to qualify." When you buy heirloom seeds, you'll generally notice that their age can range from 20 to over 50 years. To determine the exact age of the seeds you plan to plant, reach out to the supplier you're buying them from.

The Benefits of Growing Heirloom Seeds

From incredible flavor to unique characteristics, Nielsen says there’s a good reason why people keep coming back to a particular seed variety, year after year. Here, she shares impressive advantages of growing these mature seeds.

Genetic Stability

Many gardeners grow heirloom seeds for their predictable flavor profiles and growth habits. "Take, as an example, the Copenhagen Market cabbage variety. This cabbage was released more than 100 years ago in the United States by a Danish seed breeder, and people keep returning to it for its excellent flavor, crispness, and overall growth habit," says Nielsen. "This is where you find the benefit in heirloom seeds, because they're the varieties that your grandparents might have grown and have been enjoyed by people for a long time." There's a certain amount of nostalgia associated with heirloom seeds, but also genuinely good flavor to enjoy.

Typically Open-Pollinated

Heirloom seeds are open-pollinated seeds, meaning that they do not have to be carefully cross-pollinated in an enclosed setting like hybrids do, says Nielsen. This means heirlooms rely on natural pollination methods like wind, insects, or birds, either within the same flower or between flowers on the same plant.

True to Type

While pollination is a breeze with heirlooms, the seed result is impressive. "Heirlooms are stable varieties that often produce true-to-type seeds," says Nielsen. So, when you're growing an heirloom variety, you can often save seeds from this variety, and they will produce something similar to the plant you grew the previous year, as long as it’s not cross-pollinated with other plants in your garden. "This same thing is true of open-pollinated seeds, too, so while many people ascribe that only to heirlooms, any open-pollinated seed will work," says Nielsen.

Non-GMO

While most seeds available from seed companies are not genetically modified organisms (GMOs)—often because they require licensing and are only accessible to major commercial farms—open-pollinated heirloom seeds are regarded as safe and reliable. While certain heirlooms may not possess the resistance to specific pests or diseases that modern hybrids do, Nielsen says there are dependable growers who consistently produce reliable results, which is why they have remained available over time. "Heirlooms are the safer option from other seed companies if you want to avoid genetically modified seeds," she says.

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Heirloom vs. Hybrid vs. GMO Seeds

When it comes to seed types, it’s essential to understand the differences between GMO, heirloom, and hybrid varieties, as each offers unique considerations for gardeners.

Hybrid

Hybrid seeds are produced by deliberately cross-pollinating two genetically distinct plant varieties to combine desired traits such as high yield, disease resistance, and uniformity. "Hybrid plants have been bred to perform in a consistently productive manner," says Charles Dowding, author and no-dig gardener who uses compost to grow amazing vegetables. "However, there is some concern about how they are created, using two inbred lines which are forced to pollinate in unnatural conditions," he says. These seeds are often labeled "F1," meaning first generation, and must be purchased annually because the saved seeds do not produce consistent, high-performing offspring.

Heirloom

Heirloom seeds are open-pollinated varieties that have been preserved for generations, often passed down through families. They are valued for their rich flavors, biodiversity, and ability to be saved and replanted each year. Dowding explains that while heirlooms are old varieties, they are not always the best ones. He notes that some new varieties have been bred to perform better.

GMO

Genetically modified seeds have been engineered in laboratories to express specific traits, such as pest resistance. However, some consumers choose to avoid GMOs due to potential environmental impacts and health risks, as they can be genetically engineered to contain built-in pesticides and may pose other concerns. "These genetic combinations would never happen in nature," says Dowding. "They are totally unnatural because they can cross-pollinate with natural, native plants."

Can You Grow Your Own Heirloom Seeds?

You can successfully grow your very own heirloom seeds by purchasing them, cultivating the plant, and saving the seeds. Since heirloom plants are open-pollinated and not hybrids, they will grow true to type, meaning the offspring will be nearly identical to the parent plant, as long as they don’t cross-pollinate with a different variety. To ensure proper spacing to prevent cross-pollination when planting seeds, consult the seed supplier for recommended distances from other plants.

Where to Buy Heirloom Seeds

If you're looking to buy heirloom seeds, there are several great options, such as online seed companies, farmers' markets, major retailers, local garden centers and nurseries, community seed exchanges, botanical gardens, and educational institutions.