how to plant, grow & care for antirrhinums

• Common name Snapdragon
• Latin name Antirrhinum majus
• Type Half hardy annual
• Height 60cm x 30cm
• TLC rating Easy
• Aspect Full sun
• Planting position Cutting Garden or middle of the border.
• Suitable for pots Yes
• Good for pollinators Yes
• Good for cut flowers Yes

sowing antirrhinum (snapdragon) seeds

Sow the seeds on the surface of a fine seed or sieved compost and keep under a propagator cover or clear plastic bag until they have germinated. Once they have two good seed leaves, prick them out into modules and grow them on until they are sturdy plants. They can be planted out once the danger of frost has passed. 

growing antirrhinum seedlings

If you have ordered antirrhinum seedlings, they will require protection until after the last frosts when they can be planted outside. You can pinch out the growing tip to encourage the plant to bush out, but if you are going to cut them for flower arrangements this will have the same effect. Autumn sown seedlings can be planted out in a very sheltered spot in warmer areas or put in a cold frame to overwinter and give you flowers as early as the following May.

planting out antirrhinums

Gradually acclimatise your plants to outdoor conditions for 7-10 days before moving to their final position. Choose a sheltered spot in full sun, ideally with moist but well-drained soil. Prepare the final planting area well by adding plenty of organic matter (such as home-made compost) and forking it through your topsoil. You want soil with a fine tilth (or texture). 

Water plants well or soak for 20 minutes in a bucket or wheelbarrow of water if they look dry. Mark out your planting positions with empty plant pots, leaving plenty of space for plants to spread (around 30cm apart). Dig holes deep and wide enough so the crown of the plant is level with the soil surface. Backfill around each plant and firm the soil gently. You should be able to tug gently on the leaves without the plant lifting out of the ground. Water them in well and water again, with a flood, not a sprinkle, every 5-7 days (if no rain), to encourage roots to be drawn down deep. 

growing antirrhinums in pots

For growing antirrhinums in pots, use as large a container as possible, as this won't dry out so quickly and will require less watering. Place the container in a sunny sheltered position where they will not be damaged by the wind.

how to care for antirrhinums

watering

Water your antirrhinums once a week if the weather is dry or more frequently if they are growing in containers.

staking

As antirrhinums are particularly tall plants, they will need staking, or growing up through horizontally stretched jute netting. Attach the mesh to stout canes at each corner and every metre or so along the edge, to ensure the mesh stays taught. Place it over the seedlings soon after planting at about 45cm above ground so that they grow up through the squares and do not flop over.

picking

Keep picking (not to the ground but to above a pair of leaves), and they will keep flowering for months at a time. They will last 7-10 days in a vase. 

seasonal checklist

pests, diseases & common issues

pests

Luckily not many pests are interested in antirrhinums: rabbits are not keen and even slugs seem not to like them. Deer, however, might have a go, and of course there are always the smaller sap sucking insects that will head for your juicy young seedlings. Aphids might well appear on the tips in spring, so squash any that you see, and wait for the ladybirds and lace wings to come to your rescue. SB plant invigorator is a good treatment if the problem persists.

antirrhinum rust

This fungal disease first appears as circles of dark brown pustules on the underside of the leaves. If left unchecked, it can spread to the rest of the plant and kill it. Remove affected leaves as soon as you see the symptoms and destroy any badly affected plants. 

Rust can overwinter in warm conditions, which is why it is important to move autumn seedlings into cooler conditions like a cold frame. It also means that removing all spring sown plants at the end of the summer is important, to prevent any build-up of disease. Rotating plants around the cutting garden is also a good way of preventing disease of all kinds, as the life cycle of the pathogen is broken if plants are not grown in the same ground for two or three years.

damping off

The tiny seedlings of antirrhinums can suddenly wilt and die if too warm and damp or sown too thickly in the seed tray. Ensure good air circulation as soon as the seeds have germinated, and make sure you follow strict hygiene habits of washing pots and only using mains water for seedlings.

downy mildew

Downy mildew is another fungal infection that can attack young antirrhinum plants, leaving yellow patches on the upper surface of the leaves. Remove affected leaves as soon as you see the problem and ensure good air circulation. Make sure that plants are not growing too close together in the row and try not to water from above.

powdery mildew

This mildew leaves white powdery fungal growth on the leaf surface, but it is unlikely to kill the whole plant as long as you remove affected leaves promptly. It is caused by dryness at the roots and dampness around the leaves, so ensure you water at the base.

why are my snapdragons wilting?

Usually plants wilt because they are too dry or too wet, so ensure you have the watering regime right. Some fungal diseases can also cause wilting, so ensure good hygiene and air circulation.

why are my snapdragons falling over? 

This is usually because they need staking, so follow the guidance above, and make sure they are growing in full sun.

why are my snapdragons not blooming? 

Make sure you are not over feeding your plants as this can prevent flowering. Also make sure they are getting enough sunshine. It is usually a case of patience, as antirrhinums, being annuals are programmed to flower as soon as they are ready.

frequently asked questions

do slugs eat antirrhinums? 

Apparently, antirrhinums are one of the few plants that slugs do not like!

will deer eat snapdragons? 

Yes, deer will eat snapdragons. Growing them through a mesh might help protect the younger plants when they are still below the level of the mesh.

do snapdragons spread? 

Antirrhinums will only spread if they drop their seed and the winter is mild enough for the seeds or seedlings to survive the winter.

do snapdragons come back every year? 

No, in our climate they are grown as a half-hardy annual as generally they will not survive our winters, unless you live in a very mild part of the country.

are snapdragons poisonous to cats and dogs? 

They are not listed as having any toxic properties to pets.

why are they called snapdragons? 

If you squeeze the flowers gently at the sides, they do have the look of a dragon’s mouth snapping open and closed – a favourite children’s game for generations.

are snapdragons good for bees? 

Yes, pollinators of all sorts like to collect the nectar from snapdragons.

will snapdragons grow in shade? 

They will grow in shade, but they are unlikely to flower very well.

can you grow snapdragons indoors? 

No, because of their need for strong sunlight antirrhinums are unlikely to flower well indoors.

how to keep antirrhinums flowering? 

Just keep picking them – the more you pick, the more they flower.

what do snapdragons symbolise? 

They can symbolise childhood, as the name and game is so appealing for children. The genus ‘antirrhinum’ derives from the Greek word for nose, referring to their face-like appearance. The tenacity of their wild forbears which grow on rocky hillsides gives them an aura of strength, and apparently the purple varieties symbolised spirituality for the Victorians.

where do snapdragons originate from? 

Antirrhinum majus has been cultivated for thousands of years but is thought to originate from the Mediterranean regions of Spain and North Africa.

what to do with snapdragons after flowering? 

It is best to remove and compost antirrhinums after flowering. Whilst they might survive a mild winter, they can harbour disease, so are best resown every year.

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