How can you grow dahlias from seed? Follow this simple expert guide for achieving impressive blooms
Want to start from scratch with your dahlias next year? Here's everything you need to know
Whilst it can certainly be more work, growing plants from seed has several benefits and is such a rewarding task. So if you're looking to add some dahlia blooms to your plot, why not start from scratch?
If you know how to grow dahlias, you've probably come across the tuber method, which is the more traditional, straightforward way to grow the colourful flowers. However, if you're looking to cut costs in the garden or want to try something new, growing the popular plant from seed is a great idea and much easier than you may think.
To ensure your seeds thrive from sowing to their very last summer blooms, we spoke to gardening experts for their comprehensive guide on growing dahlias from seed.
How can you grow dahlias from seed?
As one of the best cutting garden flowers, dahlias are a really popular choice for homeowners to grow in their gardens. They come in all colours and have a mesmerising petal pattern, which makes them a wonderful addition.
However, it's not often people grow them from seeds, despite the process being surprisingly straightforward.
Add some sunset hues to your garden with this stunning mix of dahlia seeds.
Fill up your pots ready to plant with this nutrient-rich all-purpose compost mix.
These seed trays are hugely popular as they create a greenhouse effect with their plastic lids.
1. Planting
Whether you've deadheaded your dahlias and collected seeds or bought them from your local garden centre, starting from seed is an easy yet rewarding process.
"Dahlia seeds can be sown in early to mid-spring. Fill a pot or seed tray with moist compost, and gently firm this down. Push the dahlia seeds into the compost, and then cover the plant container with a clear plastic bag or propagator lid. As they are tender, the growing plants should be kept indoors until outside temperatures are above 5°C," says Richard Barker, horticulture expert and Commercial Director at LBS Horticulture.
With 4 years in the industry, Richard is a gardening expert at LBS Horticulture. He is keen to share his knowledge with both experienced and beginner gardeners, and prides himself on keeping up to date with the latest horticultural trends.
2. Caring for seedlings
Although it's usually recommended for dahlias to be planted in February, they can be sown later as long as they're kept protected until establishment.
"The seeds should germinate within a few weeks, and once they have grown 'true' leaves, they can be transplanted into individual pots," explains Richard.
"Transplant the seedlings into 10cm pots, and water in well. Around mid-May, plants can be hardened off by leaving them outside during the day and then bringing them in at night. Once all risk of frost has passed, the dahlias can be planted out in their final locations," he continues.
3. Post-planting out maintenance
Whether you're having dahlias as a patio container plant or planting them out into a raised bed, their maintenance doesn't end when they reach full growth.
"Dahlias can be thirsty plants, so containers will need regular watering through the growing season, and plants in the ground will need additional watering in hot, dry weather. They can grow better when given additional feeding, but this will differ depending on planting location," points out Richard.
"For dahlias in the ground, mulching with organic matter is usually sufficient. For container plants, you can provide a liquid fertiliser rich in potassium once every two weeks from July to September. Some dahlia varieties can be top-heavy when they are in full flower, so they may need to be staked with bamboo canes," he continues.
Are dahlias difficult to grow from seed?
If you've always grown your dahlias from tubers and learnt how to overwinter them, you may be apprehensive about starting them from a seed.
"Although it is more popular for dahlias to be grown from tubers, as this enables you to know the colour and the shape the blooms will be and the tubers have an already established, energy-stored root system which should result in bigger plants and earlier blooms in the first year than those grown from seed," explains Lucie Bradley, garden expert at Easy Garden Irrigation.
"If you want to grow lots of dahlias and be cost-conscious, then growing them from seeds is relatively easy, and you can expect a germination rate of between 50 and 80% when you buy seeds from a reputable supplier and sow them within 12 months," she continues.
And if you enjoy collecting seeds from your garden to grow, Lucie recommends collecting from your dahlia plants around autumn. But be warned, you won't necessarily grow the exact same-looking flower as dahlias don't grow true to type.
With over 28 years of experience working in the garden industry, Lucie has been fortunate enough to spend every day speaking to both amateur and professional gardeners.
FAQs
Can you just scatter dahlia seeds?
Should you be looking to transform your garden on a budget and quickly, you might be hoping a simple scattering of seeds will do the trick. However, it's sadly not as easy as that.
"Although you can scatter dahlia seeds, this is very rarely successful, and it may result in patchy gaps in garden borders. They are also susceptible to frost, so it is best to grow them indoors for the best results," says Richard.
"If you do want to plant them outside directly in the ground, you will need to wait until the risk of frost has completely passed and the soil is warm," he adds.
Protecting your plants from frost is particularly crucial when they're first growing, as they're incredibly vulnerable and it won't take much to stress the plant.
Do dahlias flower first year from seed?
If you're looking for some later summer flowers to perk up your garden into autumn, dahlias are a great choice.
"When you sow your dahlia seeds in late winter to early spring (February through to April), you can expect them to produce vibrant, colourful blooms from mid-summer until the first frosts of autumn in their first year," says Lucie.
"Although the plant themselves might be smaller and more compact than if you had started from a tuber, you still get glorious displays and at the same time what you planted as a seeds will have turned into a small cluster of miniature, underground tubers which can be dug up and carefully stored until the following spring when you can replant it, knowing what the blooms will be when they appear and you will get a bigger plant in the second year than the first," she says.
Then, if you want to start your new tubers earlier to avoid premature blooming, you can use a clever sandwich bag trick that will keep them protected whilst helping to start their growth cycle.
If you have chosen to plant dahlias in a pot, you might be wondering if you can keep them in there over winter. Luckily, there is a way, but it takes a lot of extra effort to keep them from freezing and rotting.
