Master the art of growing dahlias in pots and containers (2024)

Growing dahlias in pots and containers can be a truly rewarding experience, allowing you to enjoy these stunning blooms even if you’re short on space.

The key to success lies in understanding your dahlias’ needs and replicating as close as possible the conditions they’d enjoy in the garden. It’s not just about aesthetic appeal; dahlias require good drainage, frequent feeding, and the right amount of sunlight to thrive. By mastering these elements, you can transform your balcony, terrace, or patio into a dazzling dahlia display.

The first step is choosing an appropriate container that provides enough room for growth and ensures proper drainage. This helps prevent waterlogging, which can lead to root rot, a common pitfall in container gardening. Once you’ve selected the perfect home for your dahlias, focus on the soil composition. A rich, well-draining potting mix will nourish your plants and support their substantial growth. Regular care, including deadheading and staking, will keep your dahlias blooming profusely throughout their growing season.

Key Takeaways

• Ensure containers provide adequate space and drainage for healthy growth
• Use a rich, well-draining potting mix to nourish the plants
• Regular maintenance encourages more blooms and extends the flowering period.

Best Dahlia Varieties for Growing in Pots

Now that you’re ready to dive into the world of dahlias, it’s time to choose your plants. Not all dahlias are created equal – some varieties are better suited for container gardening than others.

Dwarf dahlias are a superb choice for pot cultivation. They’re small, compact, and pack a punch with their vibrant blooms. Varieties like ‘Twyning’s Revel’ and ‘Topmix Purple’ are popular choices.

Gallery Dahlias are another excellent choice. They’re known for their shorter stems and impressive flowers. ‘Gallery Art Deco’ and ‘Gallery Pablo’ are two varieties that can add a splash of color to your space.

Don’t shy away from the power of Cactus Dahlias. Their unique, spikey petals and smaller size make them a striking addition to any container garden.

Finally, consider Bishop Dahlias. These varieties have dark foliage that provides a stunning contrast to their bright flowers. ‘Bishop of Llandaff’ and ‘Bishop of Canterbury’ are crowd favorites.

Remember, when choosing dahlias for pots, consider factors such as:

• Size: smaller varieties tend to do better.
• Sunlight: Dahlias need at least 6 hours of full sun each day.
• Soil: Dahlias prefer well-draining soil.

Choosing the right container

When growing dahlias in pots, selecting the proper container is crucial to ensure your plants thrive. The right pot will provide ample space for growth and essential drainage.

Size and Space Considerations

It’s vital to choose a container that accommodates your dahlia’s roots and supports its growth. Dahlias need room to flourish, so a large pot—at least 30 cm (1 foot) in diameter and 3 times the depth of the dahlia tuber — is best.

Remember, the size of the container directly impacts the size of the plant and its blooms.

Plastic containers are lightweight and come in all sizes, making them a popular choice, and they can help keep the soil moist for longer. However, dahlias can become top-heavy as they grow, so ensure your pot is heavy enough to prevent tipping.

Drainage Requirements

Good drainage is non-negotiable when growing dahlias in pots. Without it, water can accumulate at the bottom of the pot, leading to root rot. Therfore, your container must have drainage holes at the bottom.

If there’s concern about soil loss, place a mesh screen inside the pot over the holes. When you’re adding potting soil, consider a blend that includes perlite or vermiculite to improve drainage while retaining adequate moisture.

The goal is to create an environment where water is absorbed efficiently but excess moisture can escape, keeping the roots healthy and preventing disease.

Potting Mix and Soil Composition

When setting out to grow dahlias in pots or containers, the potting mix and soil composition are fundamental to your success. These components provide the support, nutrients, and environment your dahlias need to thrive.

Selecting Potting Mix

Your choice of potting mix is pivotal in ensuring that your dahlias start off well. Dahlias require a potting mix that offers good drainage to help keep the roots healthy and prevent rot, but plenty of organic content to hold nutrients.

A blend consisting largely of coco coir with added perlite, in a ratio of about 70% to 30%, respectively, encourages excellent drainage and aeration, essential for strong growth. You can find these blends at most gardening centres, or consider mixing your own using high-quality ingredients.

Nutrient Content and Fertilization

Dahlias are quite hungry plants and will flourish when fed with a balanced fertiliser containing the key nutrients nitrogen, phosphorus, and potassium. Including well-aged compost or manure to your potting mix helps provides these nutrients and enhances the soil’s overall fertility at the outset.

Periodically test the pH level of your soil; aim for a slightly acidic to neutral pH (6.5 to 7.0) for optimal dahlia growth. Regularly monitor the moisture levels of your soil—it should be moist but not overly wet to ensure your dahlias don’t get waterlogged.

Fertilise your dahlias with a controlled-release balanced fertiliser to continually support their growth and blooming throughout the season. This kind of fertilise will include essential trace element nutrients that are essential growth, as well as the right proportions of nitrogen, phosphorous and potassium,

Planting and Caring for Your Dahlias

When growing big, hungry plants like dahlias in pots, you need to keep on top of the feeding, watering and maintenance. The key areas to focus on are proper planting of the tubers, ensuring adequate moisture without overwatering, offering the right support as they grow, and keeping up with pruning and deadheading to encourage blooms.

Planting Dahlia Tubers

When planting your dahlia tubers, part fill the pots with your chosen potting mix. Leave sufficient space for the tubers for the tubers to be plant 10-15cm below the soil surface. Plant the tubers with the eye (where the new growth comes from) facing upwards. Be gentle when planting to avoid damaging the eye, as this is crucial for the future growth.

Watering and Moisture Management

Dahlias prefer consistently moist soil but can’t tolerate being waterlogged. Water your plants until water runs out of the drainage holes, then allow the top inch of soil to dry out before watering again. Especially during the growing season, maintain a balance – not too dry, not too wet.

Support and Staking Methods

As your dahlias in pots grow, they’ll need support to protect them from wind damage and the weight of their blooms. Staking your plants early is key. You can use a cane or a cage to keep them upright. Position the stake carefully beside the tuber without disturbing the root system.

Pruning and Deadheading

Regular pruning and deadheading are essential to encourage more blooms and a bushier plant.

Pinch out the stems when they are about a foot (30cm) tall. This will encourage bushier groth and more flowering stems.

By removing spent flowers, you ensure your plant’s energy is directed towards producing new growth and blooms. Be careful not to damage the main stem or any new buds forming.

Preventing Common Problems

Growing dahlias in pots and containers can be highly rewarding, yet it’s crucial to pre-empt common issues related to pests, diseases, and overwintering to ensure your dahlias stay healthy and vibrant.

Pest Control

You’ve likely encountered an uninvited guest or two in your garden, and dahlias can attract earwigs, aphids, and slugs which may gnaw on the foliage. For slugs, consider barriers such as crushed eggshells spread around your plants.

Regular inspections are key. My favoured approach is to remove any pest like earwigs by hand. Catch pests early to prevent a full-scale invasion.

Disease Management

Dahlias in containers can succumb to fungal diseases and root rot, especially when the growing conditions are too damp or lack proper air circulation. Ensure you’re using well-draining soil and pots with adequate drainage holes.

Fungal infections, such as powdery mildew, require prompt action—remove afflicted parts and treat with a fungicide. Always disinfect your tools to prevent spreading disease.

Overwintering Dahlias

As perennials, dahlias can brave the winter with a bit of care. When foliage dies back, cut stems to several inches above the soil and allow the pot to dry out in a frost-free setting like your garage or shed. Ensure they stay dormant in cool frost free conditions

It is usually a good idea to replant the tubers in fresh potting mix at the start of the following growing season.

More on growing dahlias

You can also get much more guidance on growing red dahlias(and all other dahlias) in these posts:

• Taking care of dahlias: the trick with deadheading
• How deep to plant dahlia tubers
• Dahlia pinnata: a dahlia original
• How to grow dahlias: the complete guide to dahlia care
• How to overwinter dahlia plants and tubers
• How to stop or pinch out dahlias
• All you need to know about dahlia tubers and dahlia bulbs
• Dahlia varieties: your complete guide to all types of dahlias
• Dahlias in my garden: Six on Saturday
• Dahlia Wizard of Oz – Beautiful pink pompon dahlia
• Can you grow dahlias in raised beds?
• Do dahlias grow in Florida?
• Dahlia Wine Eyed Jill
• Can you grow dahlias in a tropical climate?
• Dahlia Ivanetti: magnificent magent dahlia
• Dahlia Night Silence – dusky pink dahlia beauty
• Visit a dahlia farm near you
• Best mulch for dahlias: a comprehensive guide
• Dahlia Islander: large, pink, loud, showy. What’s not to like?
• Heat tolerant dahlias: beat the heat with these 120 choice varieties
• Dahlia gall: identify and prevent leafy gall and crown gall in dahlias
• When to plant out dahlia tubers