When to Plant Outside
Moving dahlias outside always feels like a hopeful moment, but it is also when they are most vulnerable, especially to slugs.
I wait until the risk of frost has passed and the shoots are around 10 to 15 cm tall, around mid May. Before planting, I harden them off gradually over about a week, letting them spend more time outside during the day and bringing them back in at night.
Planting into Pots
If I am planting dahlias into pots, I am careful about the material I choose. I avoid terracotta because it is a thirsty, porous material that absorbs water from the compost. Instead, I use stoneware pots, which are not porous. They hold moisture far better and stop the plant losing water it actually needs.
Planting into the Ground
When planting into the ground, I prepare the soil well and then focus on protection straight away. I place a copper ring around the plant at soil level to help deter slugs. On top of that, I add whelk shells from Shell on Earth around the base. The uneven, hard surface creates an unfavourable environment for slugs and gives the young shoots a much better chance.
Support is important from the start. For dahlias in the ground, I use willow sticks and string to create a simple lattice. It may look modest early on, but it provides strong, flexible support as the plant fills out and starts to flower.
If I am growing dahlias in pots, I take a different approach and use a grow-through plant support. They are easy to place early and keep everything tidy without disturbing the plant later.
Once they are settled in, growth can be surprisingly fast. Getting protection and support right at this stage makes the rest of the season far easier and far more enjoyable.
My Planting Essentials
