Top of The Crops - Antirrhinum

Antirrhinum is the Latin name for a type of plant that are often known as snapdragons, or occasionally as dragon flowers. Their flowers are thought to resemble a dragon’s face, with a ‘snapping jaw’ that can be manually squeezed and made to open and close. They are found in the wild in rocky areas across North Africa, the United States, and parts of Europe.[1]

Their botanical name is Antirrhinum majus, which translates to ‘like a snout,’ making reference to the dragon’s nose. Their flower opening is rather heavy, and so the lighter weight honeybees cannot get inside. Snapdragons rely on the heavier bumblebees to pry the flowers open and pollinate them.

While the single flowered varieties are the most common, there are also double flowered varieties that bloom for longer periods of time.

Growing Antirrhinum in Polytunnels

Antirrhinum seeds need a temperate temperature of approximately 18 degrees C to grow successfully, so many people choose to sow them indoors, or using a polytunnel. It is best to sow the seeds between January and March, but some varietals can be sown in the late summer and overwinterered, resulting in flowers in the spring.[2] The overwintered varieties can grow up to 2 metres tall!

If you are using a polytunnel, place your seeds on moist compost without covering them. When the seedlings are big enough to move, you can transplant them into 7.5 cm pots or leave them in the polytunnel spaced 30 cm apart.

While most snapdragons are classified as short living half-hardy annuals, there are now fully hardy varieties available, including the Pretty in Pink Antirrhinum. They have a long flowering period.

How to Grow Snapdragons

Snapdragons are a relatively easy flower to grow in cool weather, available in a wide array of colours, heights, and varieties.[3] If you want to extend their blooming cycle, you can ‘deadhead’ them, removing the dead or dying heads of the flowers to encourage new growth.[4]

Most gardeners choose to start their antirrhinum plants indoors, either from cuttings or seedlings. If you are starting from antirrhinum seeds, press the seed on the surface of the soil, and aim plant lights at them for 16 hours per day. Once your antirrhinum seedlings have grown 6 leaves and are around 10 cm tall, pinch off the top of the stem to encourage bushiness and branching out.

When you are ready to plant them outdoors, remember that snapdragons will grow most successfully in partial shade, as they prefer cooler temperatures. Once the thermometer climbs, they may dwindle or stop blooming. If you want to mitigate this effect, you should plant your antirrhinum seeds in partial shade in the spring, to keep the full heat of the sun from affecting them negatively. If you keep them shaded and well watered, they may survive the heat of the summer and bloom again in the fall. If this doesn’t work, don’t stress – they are easy to plant re-establish again next spring.

Once your antirrhinum plants are established, they can survive sub-freezing temperatures. If you experience a cold snap, water your plants regularly – you can also add pine straw mulch to protect them from the cold, or use a polytunnel to shield them from the frost.

Antirrhinum prefer a neutral soil pH that is between 6.2 and 7.0. While they do not heavily feed, adding some compost to the soil will help them to stay healthy. The plants need to be watered regularly. When you first plant your antirrhinum seeds, you will need to keep them moist for the first 2 to 3 weeks. Once the plants are established in the soil, they’ll need approximately 2 to 3 cm of water each week. You should water near the plant’s crown, and don’t water them from overhead.

Do note that snapdragons can be affected by a wide variety of diseases, including powdery mildew, bacterial leaf spot, damping off, and botrytis. Pests also attack snapdragons, including cutworms, aphids, leaf miners, cyclamen mites, and spider mites

Harvesting Antirrhinum

Gardeners agree that there is little point in collecting antirrhinum seeds. While collecting the seeds is quick and easy, the resulting plants are not likely to be as beautiful or robust as the originals. Seed companies grow varieties separately and in a specific way to keep the plants true to form and looking their best.[5] For the best results, purchase new seeds each time you plan to plant new snapdragons.

If you do want to collect your antirrhinum seeds, wait until the flowers are dry. Pinch them off of the plant and then shake the dry seeds into a bowl. Store the seeds in a paper bag in a cool and dry place.


Sowing: Sow your antirrhinum seeds either in autumn or early spring, indoors in a sunny space or in a polytunnel outdoors.

Harvesting: Your antirrhinum flowers will start to bloom within 6 to 8 weeks of sowing, throughout the year (depending on when you sowed them).[6]









Reference list

Ioanotti, M. (2010). Growing and Caring for Dazzling Snapdragons. [online] The Spruce. Available at: [Accessed 10 Apr. 2019].

Larum, T. (n.d.). Overwintering Plants: What Is Overwintering. [online] Gardening Know How. Available at: [Accessed 20 Apr. 2020].

Lindsey, J. (n.d.). Snapdragon blog | How to collect seeds from your garden. [online] Snapdragon Life. Available at: [Accessed 20 Apr. 2020].

Royal Horticultural Society (2020). Deadheading plants / RHS Gardening. [online] Available at: [Accessed 20 Apr. 2020].

SF Gate (n.d.). How Tall Can a Snapdragon Plant Grow to Be and How Long Does It Take? [online] Available at: [Accessed 20 Apr. 2020].

Wikipedia Contributors (2019). Antirrhinum. [online] Wikipedia. Available at: [Accessed 20 Apr. 2020].