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Gardening Guide: How to Grow Snapdragon Flowers From Seed

Written by MasterClass

Last updated: Jun 7, 2021 • 4 min read

If you’re looking for tall, colorful, unique blooms in your flower garden, look no further than the snapdragon plants. Snapdragons (Antirrhinum majus) are beautiful cool-weather flowers that will add a pop of color and the buzzing of bumblebees to your spring or fall flowerbeds. Snapdragons also make lovely cut flowers that you can bring indoors for beautiful arrangements.

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Snapdragon Varieties

There are three main categories of snapdragon varieties available:

  • Dwarf varieties: These varieties can grow up to 10 inches; popular dwarf varieties include “Floral Showers” and “La Bella.”
  • Tall varieties: Tall varieties can grow up to 48 inches and may require staking; popular tall varieties include “Rocket,” “Animation,” and “Madame Butterfly.”
  • Trailing varieties: Trailing varieties will cascade downward out of hanging containers; popular trailing varieties include “Fruit Salad,” “Cascadia,” and “Candy Showers.”

When to Plant Snapdragons

Since snapdragons are a cool-weather flower, they’ll bloom best in temperatures between 40 and 80 degrees Fahrenheit—once the weather warms, their blooming will slow down or stop altogether. To give your snapdragon flowers the longest blooming season possible, start snapdragon seeds indoors—eight to 10 weeks before the last frost date.

Early indoor planting will allow you to transplant your seedlings into your garden a week or two before the last frost date. Since snapdragon plants can handle a light frost, you can purchase established snapdragon plants from the garden center and plant them directly into your garden in early spring, so they can start blooming as soon as possible.

How to Start Snapdragons From Seed

Start snapdragon plants indoors eight to 10 weeks before the last frost in your area to give them a headstart on the growing season, and ensure healthy blooms once the weather is optimal:

  1. 1. Choose and prepare the containers. Choose a container (or several) with drainage holes. Snapdragons will do best in well-draining soil, with plenty of organic matter, and a soil pH between 6.2 to 7.0. Since snapdragons do best in full sun—at least six hours of direct sunlight per day—choose a sunny spot inside your home to plant them.
  2. 2. Sow the seeds. Since snapdragon seeds are so small, you will not need to bury them in holes in the soil. Instead, sow seeds by sprinkling them across the soil surface, and then either sprinkle a light layer of soil over the top or simply press down to embed the seeds into the soil.
  3. 3. Water. Water the soil evenly. You’ll need to keep the soil moist as your seeds germinate and grow.
  4. 4. Thin the seedlings. Once your seedlings reach one to two inches tall, you’ll need to thin them back to between six and 12 inches apart to prevent competition.
  5. 5. Harden off. Harden off the seedlings before transplanting to make sure they’re ready for the change in climate.
  6. 6. Transplant. A week or two before the last frost date in your area, choose and prepare a spot in the garden that gets at least six hours of direct sunlight a day, and transplant each young plant to the garden, spacing the plants six inches apart to provide ample room to grow.

How to Plant Established Snapdragons

You can plant an established snapdragon plant into your garden one to two weeks before the last frost date:

  1. 1. Choose and prepare the flower bed. Snapdragons prefer full sun, so be sure to pick a spot that gets at least six hours of direct sunlight per day. In terms of soil, snapdragons will do best in well-draining soil, with plenty of organic matter and a soil pH of around 6.2 to 7.0.
  2. 2. Plant. Place your established snapdragon plant in a hole just a few inches wider and deeper than its root ball, then fill in the space to keep the plant secure and upright. If the stems begin to droop, insert a stake beside the plant, and secure it gently.
  3. 3. Water. Immediately after planting, water the area gently to help the soil settle.

How to Care for Snapdragons

Snapdragons are low-maintenance plants that only need basic flower care to bloom happily in your garden:

  1. 1. Water. Snapdragons need moist soil to grow—routine watering is crucial for the plants as they begin to establish their roots. Avoid overhead watering, which can encourage fungal infections like powdery mildew. Once your plants are growing well in your garden, scale back to about one inch of water a week to help them thrive.
  2. 2. Deadhead. Snapdragons will produce more blooms if you use a process known as “deadheading,” in which you remove old blooms to encourage new growth. To deadhead, locate individual blossoms that have begun to wilt and produce seed pods, and pinch off the flower (including the seed pod). When you see an entire stalk of flowers that have gone to seed, trim off the flower stalk with shears (to about a third of its height) to encourage the plant to send up a new stalk.
  3. 3. Mulch. Snapdragons will produce the most blooms in cooler temperatures, between 40 and 80 degrees Fahrenheit. If the weather starts to get too hot, mulch around the base of the plants to keep the soil cool and make the blooms last longer. If you keep watering your snapdragons through the summer (even when they’re not producing blooms), you may be able to encourage a fall bloom once the weather begins to cool again.

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