Zinnia
Zinnia elegans
Zinnias are the ultimate summer cutting flower, producing a dazzling display of large, vibrant blooms in an incredible range of colours — from hot pinks and scarlets to soft pastels, lime greens, and even near-purple. They flower prolifically from July to the first frost, and the more you cut, the more they produce. They're half-hardy annuals, so sow under cover in April (they germinate quickly at 20°C) or direct sow after the last frost in late May. They hate root disturbance, so sow in individual modules or pots rather than seed trays. Plant out into the sunniest, most sheltered spot in your garden in rich, well-drained soil. Space 25–30cm apart. Zinnias thrive in hot summers and struggle in cool, wet ones — good drainage is essential to prevent mildew and stem rot. Deadhead regularly or, better still, cut for the house — cutting above a leaf node encourages branching and more flowers. 'Benary's Giant' series produces enormous, dahlia-like blooms on long stems perfect for cutting. 'Queen Lime Orange' and 'Zinderella Lilac' are modern favourites with sophisticated colours. 'Profusion' series are compact, mildew-resistant, and ideal for containers and borders.
Plan where to grow Zinnia using our vegetable garden planner.
When to Sow Zinnia
Sow zinnia in April, May.
Time to Harvest Zinnia
Expect to harvest approximately 3 months after sowing.
Companion Plants
Expected Yield
Each plant produces 15–25+ stems for cutting over the season. Vase life 7–10 days.
Growing Tips
Outstanding cut flower; the more you cut, the more they bloom
Common Problems with Zinnia
Powdery mildew
White, powdery patches on leaves are common, especially in cool, damp weather or when plants are crowded. Space plants well for air circulation, water at the base in the morning (not overhead), and remove affected lower leaves. 'Profusion' series has excellent mildew resistance. Full sun and good drainage are the best preventatives.
Root rot and damping off
Seedlings and young plants are susceptible to damping off in cold, wet conditions. Use fresh compost for sowing, water from below, and ensure good ventilation. Don't sow too early — wait until compost temperature reaches 20°C. Avoid overwatering established plants; they prefer drier conditions.
Poor performance in cool, wet summers
Zinnias are heat-lovers and sulk in cool, rainy UK summers. Grow in the hottest, most sheltered spot available. In a poor summer, they perform much better in a greenhouse or polytunnel. Choose compact, mildew-resistant varieties like 'Profusion' for more reliable outdoor performance.
Plan your zinnia in the allotment planner
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French Marigold
Tagetes patula
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.
Daffodil
Narcissus
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.
Sunflower
Helianthus annuus
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.
Sweet Pea
Lathyrus odoratus
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.