No, snapdragons (Antirrhinum majus, USDA zones 7-10) are not reliable perennials in a cold climate. They are tender perennials, perennial in mild regions of roughly zone 7 and warmer, but they almost never survive a zone 5 winter. Most gardeners here grow them as annuals and replant each spring. They sometimes reseed, so a new plant appears where the old one died, which looks like coming back.
The tender perennial label confused me for years. The first fall I left snapdragons in the ground hoping they would return, and they came up the next spring, so I assumed they were hardy. The truth was that the parent plants had died and dropped seed, and the seedlings were what I saw. After a hard winter with no fall seed set, nothing came up at all. That is the snapdragon story in zone 5: not hardy, but a willing self-seeder.
What a tender perennial is
A tender perennial is a plant that lives for years in its native warm climate but dies when the ground freezes hard. Snapdragons fall squarely in this group, along with geraniums (Pelargonium, the zonal kind), dahlias (Dahlia pinnata), and many salvias. In a frost-free or mild-winter region they grow into woody-based plants that bloom for several seasons. In zone 5 the freeze kills them, so they behave like annuals.
The label matters because it sets your expectations. If you treat a tender perennial like a hardy one and leave it to fend for itself over a zone 5 winter, you will usually lose it. If you treat it like an annual and replant, or dig and store the roots indoors where that works, you keep it going. Snapdragons are cheap and easy to start, so most people simply replant.
Snapdragons are unusual among tender perennials for their cold tolerance at the edges of the season. They are cool-season plants that shrug off light frost and keep blooming late. So they are tougher than a tropical tender perennial like a coleus, just not tough enough to survive the deep, sustained freeze of midwinter in a cold zone. The Royal Horticultural Society rates snapdragons as hardy to about 25 degrees F (-4 degrees C) at the crown, well above what a zone 5 winter delivers.
Why snapdragons rarely overwinter in zone 5
The killer is not a single cold night but the long, deep freeze of a zone 5 winter. The ground freezes solid for weeks, and the snapdragon’s crown and roots cannot survive being frozen through. Even in a mild winter, the freeze-thaw cycles heave the plant and damage it. A snapdragon is built for cool weather, not for months of hard frozen soil.
Snow cover and a sheltered spot occasionally let a snapdragon scrape through a mild winter, especially the more perennial-leaning types. I have had one or two survive against a warm south wall under deep snow. But these are exceptions, not something to plan around. Counting on a snapdragon to overwinter in zone 5 leads to disappointment most years.
Drainage plays a role too, as it does with any marginal plant. A snapdragon in wet winter soil rots even faster than one in dry, well-drained ground. If you want to gamble on overwintering a snapdragon, give it the warmest, best-drained, most sheltered spot you have, and treat any survival as a bonus rather than the expected result.
The reliable way I keep snapdragons going year to year is not by overwintering the plants but by letting them set seed. I leave several spent flower spikes standing in fall instead of deadheading them all, so they drop seed into the bed. The next spring, snapdragon seedlings come up on their own where the parents grew. They are not identical to the parent, but it costs nothing and saves buying new plants every year.
The self-seeding habit
Snapdragons reseed readily when conditions suit them, and this is the closest thing to coming back that you get in a cold garden. The plant drops seed from its spent spikes in late summer and fall, the seed sits through winter, and seedlings sprout the next spring once the soil warms. To a gardener it looks like the same plant returning, but it is a new generation grown from seed.
The reseeded plants vary from their parents, since most garden snapdragons are hybrids and their seedlings do not come true. You might get different colors or heights than you planted. Many gardeners enjoy the surprise, and the volunteers are tough, well-adapted plants because they sprouted in place. To encourage it, leave some spikes to ripen seed rather than deadheading every one.
You can also collect the seed yourself. Let a few spikes dry on the plant, shake the tiny seeds into an envelope, and store them somewhere cool and dry over winter. Sow them indoors in late winter or directly outdoors in early spring. This gives you more control over where the snapdragons grow than relying on self-sown volunteers scattered around the bed.
Growing snapdragons as cool-season annuals
The practical approach in zone 5 is to grow snapdragons as cool-season annuals, and they reward it well. Set them out early in spring, weeks before the last frost, because they tolerate cool weather and light frost that would kill tender summer annuals. This early start gives a long spring bloom before the summer heat arrives. The Royal Horticultural Society notes that snapdragons flower best at daytime temperatures between 60 and 75 degrees F (15-24 degrees C) and fade as temperatures climb above 80.
Snapdragons stall in midsummer heat, when the bloom slows and the plants look tired. The fix is to shear them back by about a third in July, water them, and let them rebound. As the weather cools in late summer and fall, they push a strong second flush and bloom well past the first frosts, often outlasting every other flower in the bed. This cool-season vigor is their best trait in a cold garden.
Pinch young plants when you set them out to encourage branching and more flower spikes. Deadhead spent spikes through the season for continued bloom, but leave a few near the end to set seed if you want volunteers. Snapdragons want full sun and decent soil, and they make excellent cut flowers, lasting well in a vase, which is reason enough to grow a row of them.
Tall and short types
Snapdragons come in a wide range of heights, and the type you choose changes how you use them. The tall varieties like ‘Rocket’ (30-36 in / 75-90 cm) and ‘Madame Butterfly’ (24-30 in / 60-75 cm, double azalea-shaped blooms) make superb cut flowers, with long spikes packed with blooms. They need staking in an exposed spot, since the tall spikes lean and snap in wind. Plant them where they have some shelter or grow them in a cutting bed.
The dwarf and mid-height types like ‘Liberty’ (18-22 in / 45-55 cm) and ‘Floral Showers’ (8-10 in / 20-25 cm) stay under two feet and suit the front of a bed, edging, and containers. They need no staking and branch into bushy mounds covered in flowers. For a pot or a tidy border edge, these shorter snapdragons are the easier choice. They handle the same cool-season treatment, blooming early and late with a shear in between.
All types share the same hardiness story, so the height does not change whether they overwinter. A tall snapdragon is no more likely to survive a zone 5 winter than a dwarf one. Choose by how you want to use the flowers, plan to replant or let them reseed, and treat every plant the same way through the season.
The bottom line for cold gardens
Snapdragons are tender perennials that act as annuals in zone 5, and the simplest way to enjoy them is to accept that. Plant them early for a long, cool-season bloom, shear them in midsummer, and let them flower into late fall after the tender annuals collapse. Leave a few spikes to reseed, and you may get free volunteers next spring. Do not count on the parent plants returning, and you will not be disappointed.
If you garden in zone 7 or warmer, the same snapdragons may return from the crown for a second or third year, behaving like the perennials they technically are. In a cold garden, though, the honest answer is that they are perennials in name and annuals in practice. Grown that way, they are one of the most useful and forgiving flowers you can plant.