Do Dahlias Come Back Every Year: A Growing Guide To Dahlias

Dahlias are a fan-favourite for many gardeners! Yet, many wonder if these stunning flowers will return each year to bring new vibrancy to the garden. In this article, we will discuss do dahlias do grow back every year. From when to plant and flower to caring for them during winter, this is the complete guide on how to look after dahlias.

Key Info: Do Dahlias Come Back Every Year

When learning about do dahlias come back every year, you first have to think about when they mainly blossom.

Dahlias blossom most in the summer, and add a burst of vivid colour to gardens. Dahlias suit various garden styles, and blend seamlessly in everything from cottage gardens to exotic paradises. Partner them with companion plants such as cosmos, grasses, Verbena bonariensis, or cannas for spectacular combinations. Plus, they’re a favourite choice for cut flowers, and will reward you with more blooms the more you trim them. 

While you can purchase dahlia plants at garden centres during the summer, many gardeners prefer to grow them from tubers. These tubers are typically potted indoors, starting in late March or early April, and then transplanted to the garden once the threat of frost has passed. Additionally, dahlias can be grown from rooted cuttings and seeds.

In regions with colder climates, gardeners often take precautions by digging up their dahlia tubers when the first autumn frosts appear, bringing them indoors for the winter.

When to Grow Dahlias

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Knowing the right time to grow dahlias when learning about do dahlias come back every year is essential to ensure a successful and long-lasting display. Here are the key points to keep in mind:

Planting Time: Dahlias are typically planted in late March or early April, starting them indoors and transplanting them into the garden once the risk of frost has passed. In the UK, this generally means planting them out in May.

Flowering Period: Dahlias grace your garden with their stunning blooms from July to October, offering a late-summer burst of colour.

How to Grow Dahlias

Dahlias are relatively low-maintenance, but they do have specific requirements to flourish. Here’s what you need to know when following our advice as you learn about how do dahlias come back every year:

• Soil: Dahlias thrive in fertile, moist, and well-drained soil. While they aren’t too picky about soil type, adding organic matter, such as well-rotted manure, can enhance their growth. In heavy clay soil, mixing in some grit during planting will benefit them too.
• Sunlight: Dahlias love the sun. To ensure they thrive, plant them in a sunny, sheltered spot, ideally facing south or west.
• Staking: Taller dahlia varieties may require staking to prevent them from toppling over as they grow.

Where to Grow Dahlias

Selecting the right spot for your dahlias is crucial when learning how do dahlias come back every year. For instance, if you’re growing dahlias in pots, opt for high-quality, peat-free multi-purpose compost to provide the ideal growing conditions.

Growing Dahlias from Tubers

To kick start your journey about how do dahlias come back every year, you can place all your tubers in a large, shallow tray at the start of April, lightly covering them with compost. Alternatively, pot each tuber separately in a decent sized plastic pot filled with multi-purpose potting compost. Ensure that the tuber is positioned correctly, with the old stem or new shoot (indicating the top) just below the soil surface. When watering, do this thoroughly, as this will allow any excess water to drain away.

Now, it’s time to find a suitable spot to nurture your budding dahlia stars. Choose a well-lit, frost-free location such as a greenhouse, cold frame, porch, or windowsill. Keep the compost consistently moist. Around five weeks after planting, expect new shoots to emerge, gradually transforming into robust plants by the time frost in May has ended.

When to Buy Dahlia Tubers in the UK

In the UK, February is the best month to buy dahlia tubers from local garden centres. However, if you’re seeking a more extensive selection, online nurseries and specialised growers are your best bet. Consider the following factors when purchasing dahlia tubers:

• Dahlia Size: Dahlias come in various sizes, catering to different garden settings. Some are compact dwarfs suitable for bedding displays, while others are medium-sized and ideal for pots. Large dahlias, on the other hand, thrive in spacious borders or cutting patches. Before making a selection, ensure the chosen dahlia’s ultimate size aligns with your garden’s available space.
• Growing Conditions: Dahlias thrive in sheltered, well-lit spots. Before purchasing tubers, evaluate your garden’s conditions to ensure they meet these requirements.
• Tuber Quality: If you prefer shopping at garden centres for your plants, choose the right tubers carefully. Look for tubers that are large, plump, and free from any signs of rot or mould.

Where to Buy Dahlias Online

For a diverse range of dahlia varieties to grow as you know how do dahlias come back every year, here are some reputable online sources to explore:

• Crocus.
• Thompson & Morgan.
• de Jager.
• Dobies.
• Sarah Raven.

How to Plant Dahlias

Planting dahlias is an exciting step in bringing these vibrant blooms to life. Here’s what you need to know about the planting process when learning about how do dahlias come back every year:

Crucial Timing: Wait until mid to late May when the threat of frost has passed before planting your dahlias in the garden. Prepare the tuber before planting. Prune away some of the shoots, leaving around five. This will stimulate the growth of bushier plants with more abundant flowers. Any extra shoots can be used to create basal cuttings.

Harden Off: Before planting your dahlias directly in the garden, allow them to acclimatise to the outdoor conditions. 

Prepare the Soil: Dig a planting hole that measures about 30cm in diameter. To increase soil fertility, add a generous amount of well-rotted organic matter to the hole. 

Provide Support: Unless you’re dealing with dwarf dahlia varieties, these plants have a tendency to grow quickly and may become floppy, particularly if the flower heads are large. To prevent this, insert sturdy stakes or bamboo canes at all four corners of the plant. These supports will be concealed as the plant matures. Remember to tie the new growth to these supports every couple of weeks.

Container Planting: If you’re considering container growing your dahlias, choose a sizable container, at least 30cm wide and deep. Use multipurpose compost and organic matter, such as well-rotted manure, to fill the container. You can also incorporate slow-release plant food at this stage. Plant the dahlias in the container at the same depth as they were in their original pot.

How to Care for Dahlias

Proper care ensures that your dahlias flourish every year and produce plenty of blossoms. Follow these steps for ongoing care:

1. Encourage Side Shoots: Once your dahlia reaches approximately 20cm in height, promote the growth of flowering side shoots by pinching out the main growing tip. Remove the main shoot down to the top pair of leaves using either a sharp knife or your thumb and index finger.
2. Provide Support: Maintain support for your dahlias by tying in new growth to the stakes every week or so. This prevents the plant from sprawling as it grows.
3. Regular Feeding: Feed your dahlias with a high-potash fertiliser, such as tomato feed, once every two weeks. This practice ensures a steady supply of flowers. Additionally, water your dahlias thoroughly once a week to keep them hydrated.
4. Harvesting: If you’re cultivating dahlias for cut flowers, wait until they are fully open before harvesting them. This is when they are at their most vibrant and ready to adorn your arrangements.

Overwintering Dahlias

In many regions, dahlias face a frosty or wet winter that can be challenging for their survival if left in the garden. To ensure that dahlias do come back every year, we advise lifting the tubers once the foliage has been blackened by frost. 

Trim the stems back to approximately 12cm, and then, using a garden fork, carefully lift the tuber and gently remove the soil with your fingers. Place the tubers upside down in a tray lined with newspaper, allowing them to air-dry for a couple of weeks in a dry location.

Once the tubers are thoroughly dry, store them in a cool, frost-free area, ideally in a shallow tray filled with dry compost or horticultural sand. There’s no need to water them during this period, and they don’t require light, making a dark garage or cellar a suitable storage space. Do not disturb them during late March or early spring, until it’s time to pot them again.

If your garden has well-drained soil or you have limited space for lifting and storing dahlia tubers, an alternative approach is to cover the soil with a thick layer of mushroom compost and straw. This protective layer acts as insulation, preventing frost from penetrating the tubers. When spring arrives, simply rake away the excess compost.

For more growing tips, learn about adding trellis to an existing fence to increase appeal to your garden.

Deadheading Dahlias

Do dahlias come back every year if you deadhead the spent blooms and use fertiliser?

To ensure that your dahlias come back every year, deadheading is an important technique to include. Identifying spent flower heads versus buds can be a bit tricky – buds are typically round, while spent flower heads are more pointed. 

To deadhead, remove the entire flowering stem. This not only encourages new blooms but also keeps the plant looking tidy and well-groomed.

Propagating Dahlias

Do dahlias come back every year through successful propagating?

You can propagate dahlias in several ways:

• Dividing Tubers: In spring, dahlia tubers of substantial size can be divided. Press the tubers onto a tray of shallow compost and place them in a greenhouse or a sunny room with warm and moist compost. Once the tubers begin to produce shoots, use a clean, sharp knife to divide them. Each section should have at least one shoot and set of roots. Pot these divisions and grow them until the danger of frost has passed, at which point you can plant them in your garden.
• Basal Cuttings: In spring, you can take basal cuttings from your dahlias. Each tuber can hold approximately five new plants, which will flower during the summer. Another option is to purchase rooted cuttings online in spring. While these may produce smaller plants in their first year, they are well-suited for pots and still offer vibrant blooms.
• Growing from Seed: If you’re feeling adventurous, dahlias can also be grown from seed.

Problem Solving

How do dahlias come back every year if they get affected by pests?

Dahlias, like many plants, have their fair share of pests. Earwigs are a common pest, as they feast on foliage, buds, and flowers. Creating earwig traps will help to deter the critters. Do this by inserting a garden cane into the soil. Next, place an upturned garden pot filled with straw on top. During the day, earwigs will seek refuge in the pot, allowing you to dispose of them.

Slugs and snails are another common challenge, especially when it comes to new growth. Planting dahlias when they have reached a decent size can help. Additionally, placing a copper ring around the plant acts as a barrier, deterring these slimy intruders. If needed, organic slug pellets can also be scattered, ensuring the safety of your garden’s wildlife while protecting your dahlias.

The True Answer To Dahlias Coming Back Every Year

Do dahlias come back every year with the same vibrant colors, or do they tend to change over time? You will only learn this by following this guide on growing dahlias; when done properly, you should have the gorgeous flowers at their most prosperous every July – October. With proper care, from planting to overwintering, and the regular practice of deadheading, you can ensure a prolonged and vibrant flowering season. 

On the topic of potting plants, here are our recommended choices for low maintenance plants for pots.

FAQs

Sources

Crocus. (n.d.). Dahlia Search. [online] Available at: https://www.crocus.co.uk/search/_/search.dahlia/sort.0/ [accessed 20/10/23] 

Thompson & Morgan. (n.d.). Dahlia Tubers. [online] Available at: https://www.awin1.com/cread.php?id [accessed 20/10/23] 

de Jager. (n.d.). Dahlias. [online] Available at: https://www.dejager.co.uk/1150/Dahlias [accessed 20/10/23] 

Dobies. (n.d.). Dahlia Tubers. [online] Available at: https://www.awin1.com/cread.php?id  [accessed 20/10/23] 

Sarah Raven. (n.d.). Dahlia Search. [online] Available at: https://sarah-raven.sjv.io/c/1236178/1289204/15796 [accessed 20/10/23]