How to Grow Antirrhinum
'Crown Mixed' from Seed
The classic cottage garden snapdragon — a rich mix of traditional colours on self-supporting intermediate stems, flowering from June to October, with the characteristic snapping mouth that bumblebees and children both adore
There are some plants so deeply embedded in the British cottage garden tradition that they feel less like a choice and more like an obligation — and the snapdragon is one of them. Antirrhinum majus has been grown in British gardens for centuries, with its characteristic two-lipped flowers in a spectrum of colours from white through cream, yellow, pink, orange, red, crimson and bicolour, its long flowering season from June right through to the first autumn frosts, and its distinctive snap mechanism that delights children and puzzles bumblebees in equal measure. 'Crown Mixed' represents the best of the classic cottage garden type — intermediate in height at 35–45cm, self-supporting without staking, robust in disease resistance, and producing a full range of the traditional snapdragon colours that have made this flower irreplaceable for three hundred years.
Botanically, snapdragons are short-lived perennials — they are not true annuals and will sometimes survive mild UK winters, particularly in free-draining soil, to flower again the following year. But they are at their best and most reliably vigorous when treated as half-hardy annuals in the UK: sown under cover in late winter, planted out after frosts, and flowering from midsummer through autumn. The Crown series has been specifically selected for improved resistance to snapdragon rust — the main disease challenge — which gives it a significantly longer and cleaner season than older or less selected varieties.
Quick Facts at a Glance
Plant Type
Half-Hardy Annual
Sowing Time
Feb–Apr indoors · Aug–Sep for spring
Flowering Months
June – October
Position
Full sun
Height & Spread
35–45cm · 25cm
Difficulty Rating
3 out of 5 — Moderate
Understanding the Plant
Antirrhinum majus — the snapdragon — is a short-lived perennial native to the rocky hills of southern Europe and the Mediterranean region, where it grows in dry, sunny, well-drained conditions. The genus name Antirrhinum means "like a snout" in Greek, referring to the flower's resemblance to an animal's nose — though children throughout history have preferred to think of it as a dragon's mouth. The common name captures the imagination far better than the botanical one, and the snapping mechanism that gives it that name is one of the most charming features in the entire range of cottage garden plants.
The snap mechanism works because the flower's two lips are held closed by muscle-like fused petals, and only insects heavy enough to force them open — primarily bumblebees — can access the nectar inside. This is not just entertaining to watch but ecologically significant: snapdragons and bumblebees have co-evolved, and the flowers are specifically adapted to bumblebee pollination. The RHS Plants for Pollinators designation reflects this — few flowers support bumblebees as specifically and as effectively as antirrhinum.
Crown Series — What Makes It Different
The 'Crown' series was developed specifically to address the main weakness of traditional snapdragons: susceptibility to snapdragon rust, a fungal disease that causes orange-brown pustules on leaves and stems and significantly reduces the plant's season and appearance. Crown series plants show notably improved field resistance to rust, which means the foliage stays cleaner and greener for longer and the plants continue flowering vigorously into October when less resistant varieties may have already become tired and diseased. The intermediate habit — tall enough for impact, compact enough to be self-supporting — makes it the ideal border type.
The Autumn Sowing Option
Snapdragons can also be sown in August or September and overwintered as young plants in a cold frame or cool greenhouse. These autumn-sown plants establish stronger root systems over winter and come into flower significantly earlier the following spring — sometimes from late April or May rather than June. They also tend to be more vigorous and larger-flowered than spring-sown plants. If you have a cold frame or unheated greenhouse, the autumn sowing route consistently produces the finest results.
When & How to Sow
Antirrhinum seed is minute — almost dust-like — and requires surface sowing with light access. This is the non-negotiable rule that determines whether a sowing succeeds or fails. The seed needs warmth and light simultaneously, and a heated propagator makes a substantial difference to germination speed and reliability.
The Two Sowing Windows
February to April indoors — the standard approach for summer flowering. February sowings flower from June; April sowings from July or August. August to September — sow for overwintering in a cold frame, producing significantly stronger plants that flower from May or June the following year. Both windows are productive; the autumn sowing consistently produces superior plants for those with the facility to overwinter them.
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Fill pots or modules with fine seed compost and firm lightly. Water from below before sowing. The compost surface must be smooth, firm and consistently moist — antirrhinum seed is so fine that it needs good contact with an even surface to germinate reliably.
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Surface sow without covering. Antirrhinum seed requires light to germinate — do not cover with compost. Tap the seed carefully from the packet or fold a piece of paper to create a channel and roll seed along it very gently. Press the surface lightly to ensure contact.
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Place in a heated propagator at 20–22°C, or on a warm, bright windowsill. A propagator is strongly recommended — antirrhinum germinates significantly faster and more uniformly at consistent warmth. Germination typically occurs in 10–14 days, occasionally up to 21 days. Keep the compost consistently moist from below.
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Move immediately to full light after germination. Antirrhinum seedlings draw very quickly in insufficient light. A bright windowsill with rotation, or a heated greenhouse, produces compact, sturdy seedlings. Drawn, leggy seedlings can be partially recovered by deeper potting.
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Pinch out at 10cm for a bushy plant. When seedlings reach 10cm, pinch out the growing tip between finger and thumb. This forces the plant to branch from lower nodes, producing five to six flowering spikes rather than one. It delays flowering by ten to fourteen days but produces a significantly more productive and more attractive plant.
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Harden off and plant out from late April to May. Antirrhinum tolerates light cold but not hard frost — plant out once overnight temperatures consistently stay above 2°C. Space 25cm apart in full sun and well-drained, reasonably fertile soil.
Growing On Tips
Full Sun
Snapdragons require full sun for the best flower colour, most upright habit and the healthiest, most disease-resistant plants. In shade, stems become drawn and the foliage is more susceptible to rust. A south-facing border in full sun is ideal. At least six hours of direct sun per day is needed for a good display.
Deadheading
Remove spent flower spikes by cutting back to the nearest visible side shoot or bud. Regular, consistent deadheading is the single most important care task for sustaining continuous flowering from June to October. Plants that are allowed to set seed quickly reduce their flower production. Cut every week or two throughout the season.
Feeding
A balanced liquid fertiliser applied fortnightly from midsummer sustains the plant's energy through the long season. Without feeding, the later flushes of flowers become progressively smaller and the plant's overall vigour declines in August and September. High-potash feeds (tomato fertiliser) from July encourage continued flower production over leafy growth.
Rust Resistance
The Crown series has been selected for improved resistance to snapdragon rust — a fungal disease that causes orange-brown pustules on leaves and stems, most common in warm, humid conditions in late summer. Remove any affected leaves promptly. Good airflow through correct spacing (25cm) and avoiding overhead watering are the most effective preventive measures.
Overwintering
In mild areas and free-draining soils, snapdragons sometimes survive the UK winter and produce a second season of flowers the following year — usually from March or April, weeks before spring-sown plants come into flower. Do not cut plants back in autumn; leave them in the ground and see how they perform. Second-year plants are often vigorous and rewarding.
Bumblebee Pollination
Watching a bumblebee force open the closed mouth of a snapdragon, disappear inside and emerge covered in pollen is one of summer's genuine wildlife pleasures. Only bumblebees are strong enough to open the flowers; honeybees and smaller bees cannot. This makes antirrhinum an unusually specific and valuable bumblebee plant — the snap mechanism is not just charming but ecologically deliberate.
Common Problems & How to Fix Them
| Problem | Likely Cause | What to Do |
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| No germination | Seed covered or too cool | Antirrhinum must be surface-sown without covering — it is one of the most commonly failed sowings when gardeners instinctively cover the seed. Resow on the surface at 20–22°C with good light access and consistent moisture. |
| Leggy, drawn seedlings | Insufficient light after germination | Move to the brightest possible position immediately after germination. Rotate windowsill pots daily. If seedlings are already drawn, pot on more deeply — bury the leggy stem section in the potting compost, leaving only the top 3–4cm above the surface. The buried stem develops roots and the plant becomes more compact. |
| Rust (orange pustules on leaves) | Snapdragon rust fungus — warm and humid conditions | Remove affected leaves immediately and destroy — do not compost. Ensure good airflow between plants. Avoid overhead watering. The Crown series has improved resistance but is not immune. A preventive copper fungicide spray in mid-July can help in particularly susceptible conditions. Heavily affected plants should be removed entirely. |
| Flowering stops in midsummer | Plants allowed to set seed | Deadhead rigorously and consistently — remove spent flower spikes as soon as they fade. Snapdragons set seed quickly and reduce flowering once seed production begins. Cutting back spent spikes to a side shoot or bud is the key to the long season this variety is capable of producing. |
| Damping off in seedlings | Overwatering, cold, poor airflow | Water from below only. Ensure good ventilation after germination. Antirrhinum seedlings are sensitive to damping off in wet, cold conditions — warmth, light and modest watering prevent it. A small electric fan set to very low provides beneficial airflow in a greenhouse or propagator environment. |
When to Expect Flowers
From a February sowing, Crown Mixed typically comes into flower in June — the flowering season running continuously, with regular deadheading, through to the first hard frosts of October or November. A March sowing flowers from July; April from August. Autumn-sown plants overwintered in a cold frame come into flower from May, giving a noticeably earlier and longer season.
Sow indoors from February for flowers from June, or in August for an earlier, stronger display the following May — with regular deadheading, flowering continues without interruption until the first autumn frosts.
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| 🌱 Sow Indoors |
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| 🪴 Plant Out |
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| 🌸 Flowering |
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Plant Specifications
The cottage garden classic that never goes out of style
Antirrhinum 'Crown Mixed' is the snapdragon for gardeners who want the full, classic cottage garden experience — the rich mix of traditional colours, the characteristic snapping mouth that bumblebees wrestle with and children delight in, the long season from June to October, and the improved disease resistance that keeps plants looking clean and floriferous through late summer. Sow in February for a summer-long display, or in August for a stronger, earlier showing the following spring. Pin your technique — surface sow, pinch out at 10cm, deadhead consistently — and this traditional plant will reward you magnificently.
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