flower
perennial family

Iris

Iris germanica

Bearded irises are among the most elegant and dramatic garden flowers, producing large, ruffled blooms in an extraordinary range of colours — from palest ice-blue and cream through rich purples, bronzes, near-black, and vibrant bicolours. They flower in May and June, each stem producing several buds that open in succession. The flowers have an unmistakable form: three upright 'standard' petals and three falls (drooping petals), the latter decorated with a fuzzy 'beard' that gives the group its name. They're easy to grow given the right conditions: full sun and well-drained, neutral to alkaline soil. Crucially, the rhizome must sit on the soil surface, exposed to the sun — burying it is the single most common cause of failure. Plant or divide in July or August, after flowering, placing the rhizome on the surface with roots below. Face the fan of leaves north so the rhizome gets maximum sun. They're extremely drought-tolerant once established and thrive on neglect. Divide every 3–4 years when flowering declines, discarding the old centre and replanting vigorous outer sections. 'Jane Phillips' (pale blue), 'Sable' (near-black), and 'Kent Pride' (brown-gold bicolour) are outstanding UK varieties. Many are beautifully fragrant.

Plan where to grow Iris using our vegetable garden planner.

SunlightFull sun
WateringLow
Height90cm
Spacing30cm
GerminationN/A — grown from divisions or pot-grown rhizomes
Sowing MethodDirect sow
Frost HardinessHardy
Sowing DepthSurface — rhizome must sit on top of soil

When to Sow Iris

Sow iris in July, August.

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Sowing months

Time to Harvest Iris

Expect to harvest approximately 10 months after sowing.

Companion Plants

Expected Yield

Ornamental — spectacular flowers May to June; many are fragrant. Divide every 3–4 years for more plants.

Growing Tips

Plant rhizome on the surface — never bury it

Common Problems with Iris

Rhizome rot (bacterial soft rot)

The rhizome becomes mushy, foul-smelling, and collapses. Usually caused by planting too deep, poor drainage, or physical damage allowing bacteria to enter. Always plant with the rhizome exposed to sun and air. Cut out all rotten tissue with a clean knife, dust with sulphur powder, and allow to dry before replanting in a new position.

Iris leaf spot (Mycosphaerella macrospora)

Brown, oval spots with water-soaked margins appear on leaves, eventually causing them to brown from the tips down. Remove and destroy affected leaves promptly. Clean up all dead foliage in autumn. Improve air circulation and avoid overhead watering. Good garden hygiene breaks the disease cycle.

Poor flowering after a few years

Clumps become congested after 3–4 years, with rhizomes climbing over each other and flowering declines. Lift and divide after flowering in July–August. Discard old, exhausted centre sections and replant vigorous outer fans 30cm apart in refreshed soil. They'll flower well again the following May.

Plan your iris in the allotment planner

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More Flowers

French Marigold

Tagetes patula

flower

French marigolds are the workhorses of companion planting — their pungent scent confuses pests and their roots release chemicals that suppress soil nematodes. They're particularly effective planted alongside tomatoes, peppers, and brassicas. Beyond pest control, they're genuinely beautiful, producing a non-stop display of orange, yellow, and red blooms from June until the first hard frost. They're among the easiest flowers to grow from seed, germinating quickly and flowering within 8 weeks of sowing. Deadhead regularly to keep the display going. In the allotment context, scatter them generously between vegetable rows — they attract hoverflies whose larvae devour aphids. The flowers are also edible, adding colour to salads.

Full sunLow30cm

Daffodil

Narcissus

flower

Daffodils are the quintessential spring flower in Britain, carpeting woodland edges, roadside verges, and garden borders with golden yellow from February to April. They're incredibly easy to grow — plant bulbs in autumn, pointed end up, and they'll flower reliably for years with almost no care. They naturalise brilliantly in grass, creating meadow-like drifts that improve year on year. The key rule is never to cut back the foliage after flowering until it has yellowed naturally (at least six weeks) — the leaves are photosynthesising to recharge the bulb for next year's flowers. 'King Alfred' types give large trumpet flowers; 'Tête-à-Tête' is a compact miniature perfect for pots and borders. Daffodils are toxic to rodents and deer, so they're left alone where other bulbs get dug up. They're also poisonous to cats and dogs, so take care in gardens with pets.

Full sunLow40cm

Sunflower

Helianthus annuus

flower

Sunflowers are the flowers that children grow and adults never tire of — their cheerful, towering presence lifts any garden. Giant varieties like 'Russian Giant' can reach 3 metres or more, turning any allotment into a dramatic backdrop. For cut flowers, try multi-headed varieties like 'Velvet Queen' (deep burgundy) or 'Lemon Queen' (pale yellow). Sow seeds directly where they're to grow from late April — they germinate quickly and grow at an astonishing rate. In exposed positions, stake tall varieties to prevent wind damage. The seed heads provide valuable food for goldfinches and other birds in autumn — leave them standing rather than cutting them down. Sunflowers also have practical uses on the allotment: they can act as living supports for climbing beans, their deep roots improve soil structure, and they attract pollinators to your plot. Slugs can destroy seedlings, so protect them until they're large enough to withstand nibbling.

Full sunModerate200cm

Sweet Pea

Lathyrus odoratus

flower

Sweet peas are the quintessential English cottage garden flower, grown primarily for their intoxicating scent and delicate, ruffled blooms. They're climbers, reaching 1.5–2 metres, and need support — wigwams of canes, trellis, or netting all work well. The golden rule is to pick, pick, pick: the more you cut, the more flowers the plant produces. Once you let seed pods develop, flowering slows dramatically. For the longest season, sow seeds in October in root trainers and overwinter in a cold frame — these autumn-sown plants flower weeks earlier than spring sowings. Alternatively, sow in March–April under cover. Nick or soak the seeds overnight before sowing to speed up germination of their hard seed coats. 'Matucana' has arguably the strongest scent; 'Spencer' types offer the largest, most ruffled blooms. Sweet peas make sublime cut flowers, filling a room with fragrance for days.

Full sunModerate200cm