When you’re preparing your garden for winter, you might not think of your delphiniums. But giving them a head start now can make a huge difference come spring.
Why Pot Up Delphiniums in August?
Delphiniums are majestic perennials known for their striking spires of blue, purple, or white blooms. But when left in 9cm pots through winter, they can struggle with poor root development and frost damage.
By moving them into a larger pot in late summer, you give their roots room to grow, and you’ll end up with a much stronger plant come spring. This process allows the delphinium to settle into its new home, grow a robust root system, and be ready to burst into life with impressive flower spikes next year.
What Size Pot Should You Use?
Aim for a 2–3 litre pot or even larger. Delphiniums have deep roots, so choose a container that’s taller rather than shallow. If you want to keep them in containers long-term, go even bigger and consider moving them into a display pot in spring.
Step-by-Step Guide
-
Choose the right pot
Use one with good drainage. Delphiniums don’t like sitting in soggy compost.
-
Add fresh compost
Use a good-quality peat-free compost. Mix in a slow-release fertiliser or some well-rotted manure if available.
-
Remove from the 9cm pot
Gently tease out the roots if they’re congested. Don’t worry if a few break – it’ll encourage new growth.
-
Pot it up
Plant at the same depth it was growing before. Firm it in and water well.
-
Overwinter position
Keep the pot somewhere sheltered from harsh winds and waterlogging. A cold frame or greenhouse is ideal, but a sheltered wall will do fine.
The Benefits
-
Healthier, more resilient plants
-
Earlier and stronger flowering next spring
-
Better root systems that establish faster in the garden (or large containers)
So this weekend, take five minutes to get ahead. Pot up your delphiniums now, and your spring garden will thank you!
