How to Plant Dahlias
Over the years we have grown and tested many, many Dahlias and we have now curated an edit of our tried and tested favourites – Dahlias that look sensational in the garden or in a large pot and are perfect for cutting. We look for Dahlias that are consistently reliable, with strong stems and stunning florets. Our florists start adding Dahlias to our bouquets in the summer, but following the popularity of our Rose plants and Sweet Pea seedlings, you can now also buy some our favourite Dahlias to grow at home.
In our recent Instagram Live, our founder Rosebie Morton likened a Dahlia tuber to a ‘half-dead tarantula’ and marvelled at the wonder of nature – in just two to three months, this small, dry tuber can transform into a plant producing masses of glorious flowers.
There are hundreds of varieties of Dahlia, which are further divided into categories. The choice can feel overwhelming, so here are a few of Rosebie and our farm manager Rob Marsden’s absolute favourites.
Orfeo Semi Cactus Dahlia
Rosebie thinks it is extremely difficult to do this Dahlia justice in photographs. Its vibrant spiky florets are an unusual raspberry cerise and it produces masses of flowers and grows well in pots or a border.
American Dawn Decorative Medium Dahlia
Rob’s favourite Dahlia is American Dawn, a Waterlily Dahlia he also thinks looks far better in real life than in any photographs he has seen. It has graduated pink florets with a pinky lavender centre.
David Howard Decorative Dahlia
This Dahlia is close to Rosebie’s heart as it was David Howard that sold us our first Scabiosa. David Howard’s namesake Dahlia has it all – beautiful vibrant orange flowers and dramatic dark green foliage with a hint of purple bronze.
How to Plant Dahlias
You can plant your Dahlias straight into the ground once the risk of frost has passed, but for early flowers we recommend you plant your tubers into pots first.
If you are planning to plant your Dahlias directly in the ground then store them in their packaging in a cool, dry place.
Planting in Pots
Choose a pot that is a good fit for the tuber – we usually use 2-litre pots on the farm. You can plant the tubers directly into the pot but you will need a warm, frost-free place to store them until after the last frost.
Half fill the pot with good-quality potting compost and place the tuber on the compost so the neck or stem is facing up. Cover the tubers with compost but leave the neck sticking out.
Water, then place the pot somewhere warm such as a sunny window cill, greenhouse or conservatory.
Planting In Ground
You can plant your Dahlias in the ground once the risk of frost has passed (usually mid- to late May in the UK). Dig a hole that is around 30cm in depth, mix in some compost and then add your Dahlia tuber. If you have given your Dahlia a head start, then make sure the new growth is above ground. If you are planting directly, then cover the tubers but leave the neck or stem above ground.
Dahlias are surprisingly low maintenance but many people find the idea of lifting Dahlias (removing them from the ground) to store over winter off putting. However, it is not as complicated as it sounds. All you need to do is carefully dig the tubers up, remove the foliage and store them somewhere cool but frost free over winter. Here on the farm we leave our Dahlias in the ground over winter but we heavily mulch them with a good four inches of straw for protection.
Dos and Don’ts for Growing Dahlias
Do – Choose a sunny spot to plant your Dahlias.
Do – Have some horticultural fleece or straw on hand to cover you Dahlias if you have planted them out and there is any risk of frost.
Do – Feed your Dahlias once a month – we use Vitax Q4.
Do – Use copper bands, beer traps or the biological control Nemaslug to keep away slugs, which love Dahlias.
Do – Keep picking and deadheading your Dahlias to promote more growth.
Don’t – Let your Dahlias dry out – but also beware of overwatering. Once you have planted out your Dahlias they do not need much water until the plants are around 15-30cm in height.
Don’t – Let your Dahlias blow over in the wind. If they are getting tall, then it’s worth supporting them with a stake.
One of the wonderful things about Dahlias is that they are so easy to propagate – the tubers grow and can be divided to create more plants or you can take cuttings from the new spring growth. Rosebie will be hosting an Instagram Live in the next couple of weeks to show you how, and we will also share her tips here on our our blog.