How to overwinter your dahlias

There are a couple of factors to consider when deciding whether to lift your dahlias and store them over the winter or leave them in the ground. Some of these are in your control, such as soil conditions and space and others are not, such as the weather!

What works for you one year, might not work the following year if we have a particularly harsh winter. In this video I explain how I decide whether to lift or leave in my own garden and how I recommend you do it at home. If you do decide to lift, theres a step by step guide below on how to store the tubers to ensure they don't rot.

https://www.youtube.com/watch?v=mS1wu7niViU

Step 1: Timing

• When to Harvest: Wait until after the first frost has killed the foliage (leaves) of your dahlias. This usually occurs in late autumn. The reason to do this is that it puts the dahlia tuber into a dormant state and it will no longer try to produce shoots. There's nothing wrong with digging them up before the frost, but if it is particularly mild, the tuber will continue to sprout.

  
  

  

  
  

Step 2: Digging Up Tubers

• Prepare the Area: Use a garden fork instead of a spade to carefully dig around the tuber clumps, being cautious not to damage them.

• Lift the Tubers: Gently lift the tubers from the soil, keeping them intact as much as possible. Shake off excess soil.

  
  
  
  

  

  
  
  
  

Step 3: Checking and Labelling the Tubers

• Remove Excess Soil: Gently shake the tubers to remove soil any excess soil but be careful not to damage the tubers. We don't recommend washing them as the the remaining soil acts as a barrier to protect the tuber and leaves it less exposed to the element.

• Inspect for Damage: Check the tubers for any signs of rot or damage. Discard any that are mushy or diseased.

• Label them: Use plant labels and a sharpie to write the names of each variety and attach to the tuber. This will help you decide where to plant them next year.

  
  

  

  
  

Step 4: Drying

• Cure the Tubers: Place the tubers upside down in a frost free space with good air circulation for a week or two to ensure they are dry. This has to be a natural process and not in a centrally heated house as you run the risk of them dehydrating. This process also helps to cure any wounds and prevents rot.

  
  

  

  
  

Step 5: Storing

• Choose a Storage Medium: Use straw, wood shavings, vermiculite, or sawdust to store the tubers

• Pack the Tubers: Place the tubers in a container (like a cardboard box or plastic bin) and cover them lightly with your chosen medium. Ensure they’re not touching to avoid rot.

  
  

Step 6: Ideal Storage Conditions

• Temperature: Store the tubers in a cool, dark place with a temperature between 40°F and 50°F (4°C to 10°C).

• Humidity: Keep humidity low to prevent mold growth. A basement or a garage can work well if conditions are right.

  
  

Step 7: Periodic Checks

• Monitor Tubers: Check periodically for signs of mold, rot, or drying out. If any tubers show problems, remove them immediately to protect the rest.

  
  

Step 8: Prepping for Spring

• Before Planting: A few weeks before the last frost, check the tubers. If they’ve dried out, soak them in water for a few hours before planting.

• Dividing Tubers: If needed, divide larger tubers into smaller sections (each with an eye) for planting.

  
  

  

  
  

Step 9: Replanting

• Timing: Replant your dahlia tubers either under cover in March/April time or outside after the last frost date in your area, when soil temperatures are consistently warm.

  
  

By following these steps, you can successfully overwinter your dahlia tubers and enjoy vibrant flowers for next season! If you've found this video useful, this year we're including our 'Introduction to Growing Dahlias Video Course' (usually £49.99) free of charge with every tuber purchase & now is the perfect time of year to start planning your garden for next year.

Head over to our tuber webshop to check out the new varieties for 2026 and secure your dahlias for spring delivery.