6 Fast-Growing Flowers That Bloom in Weeks – Sow Them Before May Ends to Fill Border Gaps and Patio Pots With Easy Summer Color
These cheap, speedy seeds will grow hundreds of blooms in time for summer, filling your garden with flowers, quick, in all zones. What are you waiting for?
Good things come to those who wait, right? Not always. Some plants are both unabashedly beautiful and incredibly quick to flower, growing from seed to bloom in a matter of weeks. They’re like a Michelin-starred chef whipping up a microwave meal: the result is fabulous, but quick as can be. So, if you need to fill border gaps, or you're looking for an idea for a patio container whose contents didn’t make it through the winter, these fast-growing flowers will quickly fill a garden space with abundant petals.
There’s no magic happening here – all these plants rely on fast growth to survive. They're annual flowers that complete their life cycle in a year, so their sole goal is to grow blooms to be pollinated and set seed, in the hope of leaving a legacy that’ll germinate the following year. Many have also evolved to grow in drought-stricken environments so, when the right conditions arrive, they sprout fast and bloom furiously to make the very most of a short weather window. And that all means they're incredibly easy flowers to grow from seed. These guys seriously want to live.
They're abundant, too, and to keep them flowering all summer long, all you need do is keep snipping the fading blooms. As long as you keep deadheading, they’ll keep blooming. It’s their nature to self-seed, too, so you’ll likely have more flowers next year, and every year forever after, without lifting a finger! Or you can collect seeds at the end of the summer to sow again next year.
Another advantage of these quick-flowering plants is that they tend to grow slim stems, happily finding their way around bigger, more established plants in your border without swamping them. And let's not forget that their short life cycle makes it easy to breed new varieties, so there are plenty of unusual cultivars to choose from. Ready to fill those border gaps? Here’s what to sow for fast flowers within weeks.
1. Cosmos
Cosmos is the Mario Andretti of the plant world, speeding from seed to flower in as little as 45 days in ideal, full-sun conditions. Blooming on branched, wiry stems, a single cosmos plant can carry over 30 flowers at a time and, as long as you keep deadheading, will bloom continuously from late June to the first frost. And you won’t just get to enjoy the abundant flowers, because their rich nectar attracts plenty of pollinators, too.
Dwarf varieties such as ‘Sensation’, available from Eden Brothers, thrive in a container or at the front of a border, while taller varieties such as ‘Psyche White’, available from Burpee, are better in the ground. There are all sorts of colors to choose from, and a fabulous range of petal forms, too. The trick to getting Cosmos to flower super-abundantly is to treat ’em mean and keep them keen: in poorer conditions, they’ll work harder to survive and produce more blooms, so don't feed them.
2. California Poppies
While it’s the state flower of California, Eschscholzia californica has naturalized in many other states, largely because it can bloom in around 60 days after sowing so quickly establishes itself in a new home. It self-seeds freely, too, though not so much as to be a nuisance.
While the wildflower has petals in a beautifully bright orange (seeds are available from Botanical Interests), varieties are available in many tones from white through yellow and red to lovely corals and peachy pinks. The feathery leaves are almost as appealing as the funnel-shaped flowers, and the buds and seedpods are a charming shape, too.
Plants are incredibly drought tolerant so give California poppies a sunny spot and well-drained soil, and they won't take much looking after. Each flower only lasts for a few days but keep deadheading and the plant will continuously produce new buds to flower all the way into fall.
3. Cornflowers
Bachelor’s Button seeds germinate fast and bring flowers in as little as 60 days. Cornflowers typically flower for around 10 weeks as long as you snip off fading flowers, and are reliable self-seeders so will grow anew next year. These dropped seeds tend to flower earlier so, by collecting some seed in late summer to sow in May or June, too, you’ll have blooms all summer long in sun or partial shade.
The original Bacherlor’s Buttons are a striking blue but there are now varieties in white, red, pink, mauve and almost black as well. Compact varieties such as ‘Dwarf Blue’, available from Eden Brothers, do well in a pot. For borders, you'll find tall cultivars growing 3 feet high, bred for the cut flower industry as these flowers last well in a vase.
Pollinators flock to the flowers and birds feed on the seedheads. An added bonus is that you can eat cornflowers too, so sprinkle petals over salads for a pretty shot of color.
4. Sweet Alyssum
Got a gap along the front of a border where weeds keep growing? Or a dry, rocky patch where nothing does well? Sweet alyssum is the answer. As its name suggests, Lobularia maritima has evolved to grow in harsh coastal conditions, so it’ll cope with pretty much anything you throw at it as long as it has sunshine and good drainage. And you'll soon realise how it earned its common name, once you smell its sweet fragrance.
Sweet alyssum only grows to a petite three inches but spreads to 10 inches and forms a carpet of tiny flowers. Got some seeds left over? Use them to underplant a shrub or pop them into a windowbox. Results are fast, and you’ll see blooms 45-60 days after sowing. You can even re-sow in September to prolong the show.
While sweet alyssum is a short-lived perennial in warmer zones, it's generally treated as an annual.
5. Nasturtiums
One of the fastest annuals to flower, nasturtiums can bloom just 50 days after sowing. And there are so many other good reasons to grow them! For a start, both nasturtium flowers and leaves are edible with a spicy, peppery taste. Pollinators adore them, too, and so do aphids and flea beetles which makes these super-useful as companion plants to keep veggies pest-free.
Nasturtiums flower best in poor, well-drained soil and need at least five hours of sun a day. There are two types so check when you’re buying: Tropaeolum minus are bushy and self-supporting while Tropaeolum majus are climbers – or trailers, should you grow them in a hanging basket. There are so many varieties to choose from, with many petal colors and some with variegated leaves. Keep deadheading and they’ll keep on blooming right up till the first hard frost.
If your kids like to help you in the garden, then nasturtium are a great choice as their seeds are large and easy to handle.
6. Zinnias
Zinnias take around 75 days to flower, so if you sow them by the end of May, you’ll have blooms in August. If you keep deadheading them, they’ll keep flowering all the way to your first hard frost, and each bloom lasts for a long time – in a vase as well as on the plant.
Zinnias come in many forms from simple daisy-like blooms to ruffles of over a hundred petals, and it makes sense that those with fewer petals are fastest to flower. There are plenty of multicolor mixes to brighten up borders, and for pots, the foot-tall ‘Thumbelina’, available from Botanical Interests, is a pretty blend of red, pink and yellow. For the most flowers, sow them in a sunny spot.
