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How to Grow Dahlias in Pots

#1 · 16th March 2024, 9:53 am

I’m relatively new to gardening and have pots ranging from 9” to 11” and thinking of dahlias in the corner of my front garden can anyone please tell me how many tubers per pot I’m guessing one as I’m hoping for a wonderful display of colour thankyou

#2 · 17th March 2024, 9:07 am

Quote from Lee Garden Ninja on 17th March 2024, 9:07 am
Hi @calamatous Debbie,
Dahlias are a great beginner flower to grow as they are relatively fuss-free (except for the slugs when they are young) and can flower really quickly in the season. They also work really well in pots for small gardens, balconies, and terraces. However, there are a few key considerations you need to be aware of with Dahlias, mainly lifting in the winter, feeding when in containers, and positioning, as they need full sun.
Here's my beginner's guide to how to plant Dahlias in pots.
Planting Dahlias in Containers
Growing dahlias in pots can be an easy beginner plant to grow in any garden or outdoor space, offering a burst of vibrant colours and intricate blooms.
1. Pot Selection
Opt for large, sturdy pots with sufficient drainage holes to ensure proper water drainage and aeration for the dahlia roots. Choose pots that are at least 12-18 inches in diameter and depth to accommodate the dahlia tubers and allow ample room for root growth. Your pots should be fine, Debbie, but only plant one per pot; they do put on significant foliage as they grow and planting more than this means they will compete with each other for nutrients.
2. Potting Mix to Grow Dahlias
Use a high-quality, well-draining potting mix of peat-free compost, which is moisture-retentive and has slow-release nutrients. You can also look for mixes that contain a blend of organic matter, perlite, and vermiculite to promote healthy root development and prevent waterlogging. But usually, peat-free compost is free-draining enough. Don't try and use garden soil, it is too heavy and quickly dies in containers as it is a living organism that needs the ground to fully survive,
3. Planting Dahlia Tubers
Plant dahlia tubers in the pot in late spring (April to May in the UK ) after the danger of frost has passed and the soil has warmed up. Position the tubers horizontally with the eye (or growing point) facing upward (these look like little eyes or nodes sticking out, but don't panic too much). Bury Dahlia tubers about 4-6 inches deep in the potting mix. Space multiple tubers evenly in larger pots 20inch pots plus, ensuring they are at least 12-18 inches apart to prevent overcrowding. For the most part just plant one per pot.
4. Sunlight for Dahlias
Choose a sunny location for your dahlia pots where they will receive full sun for at least 6-8 hours per day. Place the pots on a patio, deck, balcony, or in a sunny spot in your garden to maximize sunlight exposure. If growing indoors, place the pots near a south-facing window or under grow lights to provide adequate light for optimal growth and blooming.
5. Watering Dahlias
Keep the potting mix moist but not waterlogged throughout the growing season. Water the dahlias deeply whenever the top inch of soil feels dry to the touch, allowing the water to penetrate the root zone. Avoid overhead watering, as this can increase the risk of fungal diseases. Instead, water the base of the plants to deliver water directly to the roots. In mid-summer, when they are flowering, and it's hot, it's preferable to place a deep saucer under the Dahlia to water them so they don't dry out and get stressed.
https://youtu.be/VpIIaKM69eo
6. Fertilizing Dahlias
Feed your dahlia plants regularly with a balanced liquid fertilizer or a slow-release granular fertilizer to provide essential nutrients for healthy growth and flowering. Dahlias are hungry plants. Begin fertilizing once the plants have established themselves and continue every 2-4 weeks throughout the growing season. Follow the manufacturer's instructions for application rates and frequency.
https://youtu.be/5BhGtCjT2TQ
7. Support
As the dahlia plants grow taller and develop heavy blooms, provide support to prevent them from flopping over or breaking. Install sturdy stakes or canes around the perimeter of the pot and gently tie the stems to the support structure using soft garden twine or plant ties. This will help keep the plants upright and stable, especially during windy conditions.
8. Deadheading Dahlias
Remove spent flowers regularly to encourage continuous blooming and prolong the flowering period. Pinch off faded blooms just above a set of healthy leaves or flower buds to promote new growth and stimulate the production of more flowers. Deadheading also helps maintain the plant's overall appearance and prevents the formation of seed heads. My guide here on deadheading roses shows you how to do that.
https://youtu.be/SKnDofyV2PQ
9. Lifting & Overwintering Dahlias
Dahlias are tender plants, Debbie, and won't survive the frost each winter if planted in the ground. Dahlias are typically treated as tender perennials and need protection from frost which is why some people grow them in pots which can be moved somewhere sheltered each winter.
Before the first frost in Autumn, carefully lift the dahlia tubers from the pots using a garden fork or shovel, not damaging the roots. Shake off excess soil and allow the tubers to dry in a cool, dry location for a few days, like a bench outside. Once dry, store the tubers in a container filled with dry straw and place them in a shed somewhere cool and dark.
Alternatively, you can leave them in the pots to see if they survive any frosts, and if not, then replace them them next year; it depends on the weather.
I hope that helps, and do let us know, Debbie, how you get on with your Dahlias!
Happy Gardening
Lee

Hi @calamatous Debbie,

Dahlias are a great beginner flower to grow as they are relatively fuss-free (except for the slugs when they are young) and can flower really quickly in the season. They also work really well in pots for small gardens, balconies, and terraces. However, there are a few key considerations you need to be aware of with Dahlias, mainly lifting in the winter, feeding when in containers, and positioning, as they need full sun.

Here's my beginner's guide to how to plant Dahlias in pots.

Planting Dahlias in Containers

Growing dahlias in pots can be an easy beginner plant to grow in any garden or outdoor space, offering a burst of vibrant colours and intricate blooms.

1. Pot Selection

Opt for large, sturdy pots with sufficient drainage holes to ensure proper water drainage and aeration for the dahlia roots. Choose pots that are at least 12-18 inches in diameter and depth to accommodate the dahlia tubers and allow ample room for root growth. Your pots should be fine, Debbie, but only plant one per pot; they do put on significant foliage as they grow and planting more than this means they will compete with each other for nutrients.

2. Potting Mix to Grow Dahlias

Use a high-quality, well-draining potting mix of peat-free compost, which is moisture-retentive and has slow-release nutrients. You can also look for mixes that contain a blend of organic matter, perlite, and vermiculite to promote healthy root development and prevent waterlogging. But usually, peat-free compost is free-draining enough. Don't try and use garden soil, it is too heavy and quickly dies in containers as it is a living organism that needs the ground to fully survive,

3. Planting Dahlia Tubers

Plant dahlia tubers in the pot in late spring (April to May in the UK ) after the danger of frost has passed and the soil has warmed up. Position the tubers horizontally with the eye (or growing point) facing upward (these look like little eyes or nodes sticking out, but don't panic too much). Bury Dahlia tubers about 4-6 inches deep in the potting mix. Space multiple tubers evenly in larger pots 20inch pots plus, ensuring they are at least 12-18 inches apart to prevent overcrowding. For the most part just plant one per pot.

4. Sunlight for Dahlias

Choose a sunny location for your dahlia pots where they will receive full sun for at least 6-8 hours per day. Place the pots on a patio, deck, balcony, or in a sunny spot in your garden to maximize sunlight exposure. If growing indoors, place the pots near a south-facing window or under grow lights to provide adequate light for optimal growth and blooming.

5. Watering Dahlias

Keep the potting mix moist but not waterlogged throughout the growing season. Water the dahlias deeply whenever the top inch of soil feels dry to the touch, allowing the water to penetrate the root zone. Avoid overhead watering, as this can increase the risk of fungal diseases. Instead, water the base of the plants to deliver water directly to the roots. In mid-summer, when they are flowering, and it's hot, it's preferable to place a deep saucer under the Dahlia to water them so they don't dry out and get stressed.

6. Fertilizing Dahlias

Feed your dahlia plants regularly with a balanced liquid fertilizer or a slow-release granular fertilizer to provide essential nutrients for healthy growth and flowering. Dahlias are hungry plants. Begin fertilizing once the plants have established themselves and continue every 2-4 weeks throughout the growing season. Follow the manufacturer's instructions for application rates and frequency.

7. Support

As the dahlia plants grow taller and develop heavy blooms, provide support to prevent them from flopping over or breaking. Install sturdy stakes or canes around the perimeter of the pot and gently tie the stems to the support structure using soft garden twine or plant ties. This will help keep the plants upright and stable, especially during windy conditions.

8. Deadheading Dahlias

Remove spent flowers regularly to encourage continuous blooming and prolong the flowering period. Pinch off faded blooms just above a set of healthy leaves or flower buds to promote new growth and stimulate the production of more flowers. Deadheading also helps maintain the plant's overall appearance and prevents the formation of seed heads. My guide here on deadheading roses shows you how to do that.

9. Lifting & Overwintering Dahlias

Dahlias are tender plants, Debbie, and won't survive the frost each winter if planted in the ground. Dahlias are typically treated as tender perennials and need protection from frost which is why some people grow them in pots which can be moved somewhere sheltered each winter.

Before the first frost in Autumn, carefully lift the dahlia tubers from the pots using a garden fork or shovel, not damaging the roots. Shake off excess soil and allow the tubers to dry in a cool, dry location for a few days, like a bench outside. Once dry, store the tubers in a container filled with dry straw and place them in a shed somewhere cool and dark.

Alternatively, you can leave them in the pots to see if they survive any frosts, and if not, then replace them them next year; it depends on the weather.

I hope that helps, and do let us know, Debbie, how you get on with your Dahlias!

Happy Gardening
Lee

#3 · 20th March 2024, 6:21 am

To grow dahlias in a pot, choose a large container, provide well draining soil, ample sunlight, regular watering, and fertilizations for vibrant blooms.