Dahlias come in a huge range of colours from bright whites and yellows to deep pinks, purples, reds, and more. With shapes aplenty, you can enjoy everything from cactus to anemone, single, collarette, decorative, ball and even Dahlia Pompon.
Sizes are also bountiful, and dahlias range from dwarf dahlias of 35cm high to trees towering well over 2 metres. Their flowers can reach the size of dinner plates and go all the way down to small delicate balls, so there are plenty of options available.
Dahlias come in a huge range of colours, shapes, and sizes
One of the most popular and spectacular perennial flowers you can grow at home, dahlias are easy to grow and reward you with abundant flowers throughout the warmer months. In this guide, we’ll discuss when to plant dahlias, how to grow dahlias from seed giving you everything you need to know to grow these show-stoppers in your garden!
Growing Dahlias from Seed vs Tubers
Dahlias are commonly grown from tubers (bulbs) but can also be grown from seed. Lets break down growing Dahlias from seed below:
Cost
A packet of dahlia seeds will set you back an average of $5 for 50 seeds whereas a dahlia bulb will cost you around $9-17 per bulb. So, if you’re watching the pennies, it’s a bit of a no-brainer.
True to Type
A dahlia tuber is harvested from a parent plant so will be identical to its parent. Because of this, you’ll know the exact colour and style you’ll end up with when planting dahlias from tubers. Propagating from seed, however, results in a random specimen based on the genetics of the seed and insect pollination, which modifies its genetic makeup. As a result, you won’t know the colour or size of your dahlias until they flower.
This creates a unique experience when growing from seed which can be an exciting way to experience these beauties at home!
Flowering Performance
Dahlias grown from seed or tubers result in a flowering plant in their first year. Seed-grown dahlias will develop tubers as they grow and become stronger as the years go on.
Where and When to Plant Dahlias
Climate
Dahlias can grow in most climates but prefer warmer areas because they don’t handle frost well. So, you should plant dahlia seeds after the risk of frost has passed.
Dahlia tubers handle living in well-draining soil throughout their dormancy, but if you experience cold winters or your soil is prone to waterlogging, you may be better off digging up your tubers at the end of the growing season and storing them in a cool, dry place until next year.
Position
Dahlias are sun lovers, so they will flower best when they receive at least 6 hours of sun. Morning sun is best, and a sheltered position away from strong winds will help protect their stems from breakages.
Soil
Well-draining, rich, fertile soil is ideal for growing dahlias from seed and you should mulch to keep weeds at bay and keep soil cool in summer. Dahlias are resilient and will grow in suboptimal soils such as heavy clay, but don't expect a strong performance.
Water
Dahlias are quite drought-resistant once established, but keep them well-watered and fed regularly throughout the flowering season for best performance.
How to Grow Dahlias From Seed
Growing dahlias from seed is easy if you know what you’re doing, so let’s lay the groundwork.
Soil Preparation
Dahlia seedlings are best planted in the garden after the last frost date and can be started early indoors. This gives you lots of options compared to many other flowers.
Sowing Your Dahlias From Seed
Ready, set, sow! Specifically, sow seeds 5mm deep in seed-raising mix and keep them nice and moist. If you are sowing in spring or summer, you can do so directly into their final growing position in the garden if preferred. If you’ve played your cards right, your dahlia seedlings should appear in 10-14 days.
Planting Dahlias From Seed
Transplant your dahlias into a sunny part of the garden when they’re large enough to handle and the danger of frost has passed. But don’t just put them anywhere! Instead, plant them in well-draining soil enriched with organic matter and rotted manure.
Caring for Dahlias when Growing From Seed
Start your care routine by mulching around the dahlia seedlings. This keeps weeds at bay and keeps the soil cool in summer. You should feed your dahlias with a liquid fertiliser when buds appear, then stake them as required. Oh, and don’t forget to protect them from the wind to avoid stem damage!
If you follow these steps, your flowers should appear about 3-4 months after germination.
Harvesting your Dahlias From Seed
Your dahlia plants grown from seed will produce tubers, which once mature can be lifted and separated at the end of the growing season. These tubers will grow identical flowers to the ones you’ve just grown, so essentially, you will create your own unique variety of Dahlia!
At the end of the growing season let your dahlia plants die back before cutting them off at ground level. This will allow energy to return to the tuber, energising it for a bigger and better flowering season next year.
How to Harvest Dahlia Flowers
Dahlias are best cut as soon as the blossoms open and preferably in the cool of the early morning. Cut using secateurs and place straight into a vase of tepid water.
Dahlias make excellent cut flowers and last well in vases. They are also very popular competition flowers, so why not look at entering your blooms in your local agricultural or flower show?
