If you want colour that lasts for months rather than a few weeks, start by choosing the best flowers to plant for the sun, soil and space you actually have. Matching the plant to the place makes the biggest difference.
This guide covers eight reliable flowers — zinnias, marigolds, cosmos, petunias, sunflowers, dahlias, lavender and coneflowers — with each one’s type, bloom time, sun needs and care.
Annuals finish their life in one season and usually flower for a long time. Perennials return for several years and need less replanting once established.
Start with sun, soil and space
Most colourful border flowers need full sun: at least six hours of direct light a day. Petunias, lavender and coneflowers flower poorly with much less, so watch your bed for a day before you buy.
Almost all also need soil that drains well. Lavender can rot in heavy, wet ground, while cosmos flower better in soil that is not too rich.
Check mature size, too: a sunflower can pass six feet, while a French marigold may stay under a foot, so put tall plants at the back. Thinking about sun, soil and size first is the easiest way to narrow a catalogue down to the best flowers to plant for your plot.
Illustrative image: a sunny summer border of zinnias, marigolds and cosmos.
The best flowers to plant for a sunny bed
Zinnias are annuals that bloom from summer until the first hard frost, in red, orange, pink, purple, white, yellow and lime. They need full sun and well-drained, fertile soil. Sow seed after the last frost, a quarter of an inch deep, and space plants 9 to 12 inches apart for air flow, which helps reduce powdery mildew. They flower six to eight weeks after sowing. Pinch young plants for branching, and deadhead regularly.
Marigolds are annuals that bloom from early summer to the first frost, in gold, orange, yellow, red and cream. They grow best in full sun and moderately fertile, well-drained soil. Sow seed directly once the soil has warmed, or buy young plants. Plants flower about eight weeks after sowing. French marigolds stay compact, at roughly 8 to 12 inches; taller African types mature more slowly, so plant those earlier. Water at the base, not overhead.
Cosmos are annuals with feathery foliage and daisy-like flowers in pink, white, purple, red and yellow, blooming from summer to early fall and often until frost. They need at least half a day of sun and do best in full sun. Rich soil produces leaves instead of flowers, so average or poor soil is fine. Sow indoors four to six weeks before planting out, or directly once the soil warms. Tall varieties reach three to four feet and may need staking.
Illustrative image: petunias and marigolds flowering in containers and a sunny border.
Long-flowering annuals for pots and baskets
Petunias are treated as annuals in most areas, although they can be tender perennials in USDA Zones 9 to 11. They bloom from spring until frost, in almost every colour, and are especially useful for containers. They need full sun or they become spindly. Plant out after the last frost, about a foot apart, in well-drained soil. From seed, start indoors eight to ten weeks before your last frost.
Water petunias thoroughly weekly in the ground, more often in pots, and feed monthly. By midsummer many get leggy, so cut shoots back by about half, then water and feed.
Sunflowers (Helianthus annuus) are annuals and the tallest flower here. Most varieties mature in 70 to 95 days and flower in summer. Dwarf types stay around a foot tall; large varieties grow far taller, so check the packet. Sow seed directly where it is to flower, after frost, once the soil reaches at least 50°F (10°C), 1 to 1.5 inches deep and about 6 inches apart, in six to eight hours of sun, sheltered from wind.
For a small space, the best flowers to plant are compact types of these same annuals — dwarf sunflowers, dwarf zinnias and trailing petunias all fit in pots.
Perennials that come back year after year
Coneflowers (Echinacea spp.) are hardy perennials in USDA Zones 3 to 9, with pink-purple, daisy-like flowers and a raised central cone. Newer varieties add white, yellow, orange and red. They bloom in midsummer and continue, on and off, until frost.
They prefer full sun and well-drained soil, tolerate poor soil, and are drought-tolerant once established. Space plants 1 to 3 feet apart. Buy young plants for flowers soon, because seed-grown plants may not bloom for two to three years.
Lavender is a bushy perennial grown for blue-violet flower spikes and scented foliage. English lavender (Lavandula angustifolia) is hardy to USDA Zone 5, grows 1 to 3 feet tall, and often blooms twice in a season.
It needs six to eight hours of sun and sharp drainage. Wet ground is the most common cause of failure. Lavender is slow from seed, so buy starter plants and set them out in spring, 2 to 3 feet apart. Prune in spring by about a third, but not into old, bare wood.
Dahlias are tender perennials, winter-hardy only in Zones 8 to 11. In colder areas, lift and store tubers before the first hard freeze, or treat them as annuals. Plant tubers in late spring, after frost, when soil reaches about 60°F (15°C), in full sun and fertile, well-drained soil. Most bloom about eight weeks after planting, from midsummer into fall. Stake tall varieties at planting, and do not water tubers heavily at first, as cold, wet soil can rot them.
Illustrative image: coneflowers and lavender in a sunny perennial border.
Colour by season and by colour scheme
No single flower blooms from spring to frost, so a long display comes from overlap: petunias in spring, zinnias, marigolds and cosmos in summer, coneflowers from midsummer, and dahlias into fall.
The Old Farmer’s Almanac guide to flowers for continuous colour makes the same point: use perennials as the framework, then fill gaps between their flowering periods with annuals.
For colour, plant one colour in a large group for a calm effect, pair opposites such as purple lavender with yellow zinnias for contrast, or use neighbouring colours such as pink, red and orange. Plant in groups of three or five, not scattered singles.
Planned this way, the best flowers to plant are not always the brightest ones in the shop. They are the ones whose bloom time fills a gap in your bed.
Planting and care basics
Clear weeds and dig in compost. For coneflowers, the Old Farmer’s Almanac coneflower guide suggests loosening soil 12 to 15 inches deep and mixing in compost, good practice for most of these flowers.
Plant annuals and tender plants only after your last frost date, and harden off indoor-raised seedlings for a week first. Water new plants in well, then water deeply and less often, so roots grow downwards. Mulch once established, away from stems and lavender crowns. Most need roughly an inch of water a week in dry weather, pots more.
Deadheading extends flowering the most: removing faded zinnias, cosmos, marigolds and dahlias pushes the plant to make more buds instead of seed. Feed with restraint — petunias in pots benefit from feeding, but cosmos and lavender flower worse in rich soil.
Illustrative image: sunflowers and dahlias flowering in a late-summer bed.
What seeds and plants typically cost
Costs vary by country, shop and variety, so treat these figures as typical ranges only, not quotes.
- Zinnia, marigold, cosmos and sunflower seed: typically about $2 to $5 per packet.
- Petunias: seed typically about $3 to $6 per packet; bedding plants typically about $3 to $7 each, less per plant in a multi-pack.
- Dahlia tubers: typically about $5 to $12 per tuber, more for named varieties.
- Coneflower plants: typically about $8 to $18 per potted plant.
- Lavender starter plants: typically about $5 to $12 each, usually better value than slow-germinating seed.
Seed-grown annuals give the most flowers for the least money. Perennials cost more at first, but return for years, so their cost per season falls. Many gardeners mix both when they choose the best flowers to plant for a new bed.
A simple plan to copy
For a sunny bed about 10 feet long, use lavender and coneflowers as the backbone, French marigolds at the front, zinnias and cosmos in the middle, and dahlias and sunflowers at the back.
Plant annuals after your last frost, water while they settle in, and deadhead weekly: marigold colour early, zinnia and coneflower colour through midsummer, and dahlia colour into fall.
Start small, note what flowered well, and adjust next year. In the end, the best flowers to plant are the reliable ones that suit your sun and soil and earn their space.