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Home & garden.

Updated: 10 Jan 2022

How to grow antirrhinums

Antirrhiums (snapdragons) flower all summer and are loved by bees. Discover our best antirrhinum varieties and tips for how to grow them.
CT
Ceri Thomas
Antirrhinum

Antirrhinums are a traditional favourite that are essential for any cottage garden and are popular with bees and other pollinating insects. There are two types to choose from: snapdragons that are fun to squeeze open, and trumpet blooms that make a wonderful display in a vase. Both types come in a huge range of colours, including some sophisticated bronze tones and bicolours, and have a long flowering season to brighten up any border. Most varieties suffer from rust towards the end of the summer, but the best shrug it off and keep flowering well into September.

Which? Gardening magazine grew 25 varieties to see which would give us the best display.


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Key facts

PLANT TYPE Tender perennial (grown as annuals)

POSITION Sun or light shade

SOIL Any

How to grow antirrhinums: month by month

JanuaryFebruaryMarchAprilMayJune


SOW
PLANTPLANT/FLOWERING
JulyAugustSeptemberOctoberNovemberDecember
FLOWERINGFLOWERINGFLOWERING


Best antirrhinum varieties

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Best Buy antirrhinums
What it looks likeVariety nameHeight x spread
70 x 40cm
The striking magenta flowers of this variety are a single tone, but have intriguing white flecks on the outside, which add interest. The blooms are traditional snapdragons and are held high on the strong, upright stems, which didn’t need much support. The plants in our trial were a very uniform height, making a great display. The foliage stayed green and healthy looking, and the plants flowered to the end of August when they started suffering badly from rust. Peak flowering: July-August
What it looks likeVariety nameHeight x spread
80 x 55cm
This is a tall variety that would be great for growing for cut flowers or to provide height in a border. We found that it germinated well and started flowering in June. The blooms were more shades of dark orange than bronze, but were attractive nonetheless. They are also more open than traditional snapdragons. The stems were long and strong, and didn’t need any support. The plants did eventually become infected with rust, but not until September and it didn’t stop them flowering. Peak flowering: June-September
What it looks likeVariety nameHeight x spread

How we test antirrhinum

We sowed the seeds indoors during March, using a Best Buy compost for sowing seeds, and planted out in May at our trial site in the Cotswolds. We assessed the antirrhinums throughout the summer, noting how well they flowered and how well they coped with the weather, including if they needed support to keep upright. We also noted whether any plants were suffering from rust or any other pests or diseases. All varieties were regularly deadheaded to keep them flowering for longer.

Caring for your plants

Sowing

Sow seeds in autumn or early spring in a greenhouse or on a sunny windowsill. Sow them thinly on the surface of a Best Buy compost for sowing seeds, water and put in a propagator or clear plastic bag. They should take between seven and 10 days to germinate. Transfer seedlings, when large enough to handle, into pots of a Best Buy compost for raising plants and grow on in a greenhouse or coldframe.

Planting

Plant out after danger of frost has passed in late spring. Early-autumn sowings should produce early flowers in May. Plant in pots or in a sunny or lightly shaded spot in a border.

Prolonging the display

To prolong flowering, feed weekly with a potash-rich fertiliser, such as tomato feed, and deadhead spent blooms regularly. Keep plants well watered and support taller varieties if required. 

At the end of the season

At the end of the season in early autumn, pull up your plants. They can overwinter in a mild year, but they’re best sown from seed each spring or autumn.

Common growing problems

Rust

Rust is a fungal infection of the leaves that strikes late in the summer. You can treat with Scotts Fungus Clear but, as antirrhinums are mainly grown as annuals, it’s easy just to dispose of infected plants.

Aphids

Sap-sucking insects, such as aphids, can also be a problem. Remove the aphids by hand if the colonies get to be a problem, or treat with Best Buy Neudorff Bug Free Bug & Larvae Killer or Westland Resolva.

Read more about aphids