Snapdragon Plant Profile

Snapdragon flowers
Ian Lee/flickr/CC By 2.0

Bright snapdragon flowers bloom profusely throughout cool weather in intensely saturated colors (almost every hue) and are real standouts in either the spring or fall garden. The flowers start blooming at the bottom of the stalk and work their way up, making for a long period of bloom. Although snapdragons tend to stop blooming in heat of mid-summer, if you keep them watered, they will perk up and carry your garden through the fall.

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11 Things You Should Know Before Growing Snapdragons

Their botanical name, Antirrhinum, means "like a snout" and refers to the seed pod's resemblance to a calf's nose. The flowers resemble opening mouths when they are pressed on their sides. The openings of the flowers are snapped tightly shut and require more pressure to open than a honeybee can provide, so snapdragons rely on heavier bumblebees for their pollination. The alternate, lanceolate leaves are arranged in a spiral around the stem.

  • Botanical Name: Antirrhinum majus
  • Common Name: Snapdragon, dog's mouth, lion's mouth, toad's mouth
  • Plant Type: Perennial
  • Mature Size: 6 to 48 inches depending on the variety
  • Sun Exposure: Full sun to partial shade
  • Soil Type: Well-draining, rich, moist
  • Soil pH: Slightly acidic to neutral
  • Bloom Time: Spring and fall
  • Flower Color: White, yellow, pink, red, orange, peach, purple, and violet
  • Hardiness Zones: 8, 9
  • Native Area: Europe and North America
Snap dragon by fence
Thang Tat Nguyen / Getty Images
Mid section of woman selecting snapdragons (antirrhinum) from flower farm field
Kinzie Riehm / Getty Images

How to Grow Snapdragons

Snapdragons are undemanding and can grow in a wide selection of colors and heights. They are at their best in cool weather. Snapdragons are tender perennials that are only hardy in U.S. Department of Agriculture Hardiness Zones 8 or 9. They can repeat bloom throughout the season but do best in the cool of spring and fall and throughout the winter in mild climates. Deadheading can increase the number of buds that are set, but since the flower stalks begin blooming from the bottom up, they have a fairly long bloom duration anyway.

In most areas, they are commonly grown as annuals. Even when they do overwinter, they never seem to bloom as robustly as they did in their first year, which leads many people to think they are biennial. However, they should form seed pods in their first year. If you are lucky, they may even self-sow.

Snapdragons are affected by few pests or diseases. Rust and other fungal diseases can be a problem, especially in wet seasons. If you live in a damp or humid area, look for resistant varieties. Snapdragons may also attract aphids.

Light

Your snapdragons will bloom most profusely in full sun to partial shade in the spring. Once the temperature heats up, they may stop blooming altogether. Planting them in partial shade and keeping them well watered will help them make it through the summer and likely bloom again in fall. However, they are quick to get established and it can be just as easy to replace your snapdragon plants each season.

Soil

Snapdragons like a neutral soil pH between 6.2 and 7.0. As short-lived plants, they are not heavy feeders, but adding organic matter will help keep them healthy and blooming.

Water

Snapdragons need adequate watering. When growing snapdragon, keep moist for the first few weeks. Once established, snapdragon will need approximately an inch of water per week in times of no rainfall. Water near the crown of the plant and avoid overhead watering to keep your snapdragon healthy. Once established, let the soil dry about an inch deep before watering.

Temperature and Humidity

Snapdragons prefer cooler temperatures. Snapdragons grow best when nighttime temperatures are in the low 40s and daytime temperatures in the low 70s Fahrenheit. Once established in the bed and hardened off, they can withstand sub-freezing temperatures. Make sure they stay well watered during cold spells and add a layer of pine straw mulch, and they can last for quite some time. If you should get record low temperatures, cover snapdragons with pine straw for a few days until the chill has passed.

Fertilizer

Apply fertilizer when the plants first start producing flowers. Use a standard, well-balanced all-purpose fertilizer, such as a 10-10-10 product, at a rate of three pounds for every 100 square feet of the flowerbed. Water well to minimize the risk of nitrogen burns and to help the fertilizer reach the roots.

Propagating Snapdragons

Snapdragons can be winter sown, meaning you can toss the seeds out in late fall or even on top of snow, and most will germinate in the spring.

However, snapdragons are most often either started indoors, 8 to 10 weeks before the last frost date, grown from cuttings, or purchased as seedlings. When starting from seed, simply press the seed on the surface of the potting soil. Snapdragon seeds need light to germinate.

When seedlings have developed about six true leaves, pinch the top of the stem off to encourage branching and a fuller plant. You can do this with purchased seedlings too.

Transplant snapdragons outdoors a couple of weeks before your last frost date. Snapdragons can handle a light frost or two.

Toxicity of Snapdragons

For humans, it is believed that all parts of the snapdragon are poisonous if ingested. The American Society of Prevention of Cruelty to Animals says snapdragons are nontoxic to dogs, cats, and horses.

Pruning

Regular deadheading will keep your snapdragons blooming longer. They will not need much care early in spring, but add mulch to help keep the soil cool and moist, which aids in handling the summer heat.

Some of the taller varieties will need staking unless they are planted close enough to other plants to lean on them.

Snapdragons are tender perennials and may die off in colder climates. If they do survive the winter, prune them back by about 1/3, to encourage new growth. Do not be too disappointed if they do not last long. Snapdragons tend to go downhill after their first year and it is best to start fresh every year. Many varieties will self-seed and come back on their own, although as hybrids, they will not always look like the original plants you planted.

Landscaping

Their spiky, bright colored flower stalks make a nice foil for the cooler shades of most spring flowers like brunnera and bleeding heart. Planted in clusters, they can help a border transition from the spring ephemerals to peak hot season.

The pale yellow varieties are the easiest to blend into a mixed border and work nicely with pinks, purples, and even reds.

Breeders have been playing with snapdragons for a few years now and there are trailing and creeping varieties becoming more widely available. These are great filler plants for containers, baskets, and tucked into walls.

Varieties of Snapdragons

There are tall varieties and dwarf varieties and just about everything in between. Check the label or packet of the variety you are choosing.

Dwarf plants mature at a height of about 6 to 15 inches and form dense, bushy plants with lots of flower stalks.

Tall varieties tend to be less bushy and spikier in habit, reaching a height of 30 to 48 inches.

Some varieties bridge the two extremes, growing mid-sized from 15 to 30 inches. Of course, the actual size and fullness of the plants will also depend on growing conditions.

New snapdragon varietals are always emerging. Most are sold as multi-color blends, but you can sometimes find individual colors in both seed and seedling. Some of the more popular series include:

  • Arrow: Vivid colors on strong, branching stems that grow 2 feet tall
  • La Bella: A nice blend of colors from pale to bronze to deeply saturated which grow 12 to 18 inches tall
  • Rocket: A dependable multi-colored series that grows about 2 to 3 feet tall