When it comes to growing dahlias in containers, it can be frustrating to find reliable information. But fear not! I’ve got you covered. Over the years, I’ve experimented with different techniques and have developed a successful method that I’m excited to share with you.
The Versatility of Dahlias
Traditionally, only dwarf or low-growing dahlias were recommended for container gardening. However, I’ve discovered that any height of dahlia can thrive in a container, including those reaching four feet or taller. Imagine the beauty of a privacy hedge on your patio or balcony, or the added elevation and texture that different heights of dahlias can bring to your deck garden.
Starting Early Indoors
To get a jumpstart on the growing season, I recommend starting your dahlia tubers indoors during the first week of April. Most suppliers won’t send out tubers until around this time due to weather conditions. By starting early, some varieties may even start blooming by the last week of June.
The Right Container and Potting Soil
When it comes to containers, opt for heavy-weight, sturdy, plastic pots that have drainage holes. I prefer the azalea style, which provides stability and a pleasing aesthetic. As for potting soil, I recommend using a coarse soilless mix like Ball’s Growing Mix #2. It’s important to ensure that the soil is loose, drains well, and doesn’t contain clay, as dahlias don’t thrive in clay soil.
Planting Technique
Planting depth is crucial for dahlia tubers. Place the tubers horizontally in the potting soil, making sure to leave about a quarter-inch of space between the non-eye end of the tuber and the side of the pot. This allows room for the roots to grow. Cover the tuber with enough soil to just hide it, mist with warm water using a spray bottle, and avoid overwatering at this stage.
The Secret Ingredient: Copolymer Crystals
One of my “secret” ingredients for successful container gardening is the addition of acrylic copolymer crystals to the potting soil. These crystals absorb and release water to the roots, preventing overwatering or drying out. They also help keep the roots cool and protect them from freezing. Simply mix the crystals into the potting soil according to the label instructions for your pot’s diameter.
Staking and Support
To prevent your dahlia stalks from breaking in the wind or if the pot falls over, insert a stake into the pot before covering the plant label with soil. Use steel stakes covered in green plastic for strength and ease of use. Attach the stake to the container using plant tie-wire or string, and ensure that the stake stands upright next to the stalk. For taller varieties, you may need to tie the stalks to the stake for additional support.
Care and Maintenance
Water your container dahlias when the soil is almost dry, being mindful not to overwater. The copolymer crystals will help prevent the tubers from drying out. Feed the plants every 7-10 days with a balanced fertilizer like Ra·pid·Gro Bloom Builder. Pinch out the growth tip of the stalk when the plant has three or four sets of leaves to encourage bushier growth and more flowers.
Moving and Protecting Your Plants
One of the advantages of container gardening is the ability to move your plants as needed. This flexibility allows you to optimize the flower show by turning or rearranging pots. Consider bringing your pots indoors during hailstorms or thunderstorms to protect them. Additionally, cover the plants if there’s a frost warning. By being proactive, you can extend the blooming season and enjoy more beautiful dahlia flowers.
Keep a Record and Have Fun!
Don’t forget to keep a growth record of each dahlia and take photos for future reference. This will help you track their performance and identify any patterns or factors that contribute to success or challenges. Remember, this method of growing container dahlias is not set in stone. Feel free to experiment and adapt it to suit your unique circumstances and preferences.
Happy gardening!