Quote from Lee Garden Ninja on 14th April 2025, 11:14 am

Hi @denise

Thats a real shame that your Sarah Raven Dahlias have not survived past year one. I could do with a bit more info as to why that is. However, I'm guessing you didn't lift and store your Dahlias? If not this is the prime reason for Dahlias not repeat flowering in year two.

If you’re in the UK or anywhere frost-prone, you’ll need to lift and store your dahlias properly if you want a dazzling encore next year. This is why, personally, I don't grow Dahlias, I find them a faff compared to other herbaceous perennials.

Step 1: Know When to Lift Your Dahlias

As soon as the first frost blackens the leaves—usually late October into November—it’s go-time. That frost tells the plant that its about to go dormant. But because Dahlias are tender here in the UK, they won't survive heavy frost or any water logging, so they need to be lifted, unless they're in raised beds in a warmer, sheltered part of the country.

Don’t leave them in soggy soil. Cold and wet Dahlias quickly turn to mushy tuber soup which results in a dahlia disaster.

Step 2: Cut back your Dahlias, then Lift Carefully

• Use sharp secateurs to cut the stems down to 10–15cm above the base.

• Grab a garden fork (NOT a spade – we’re not wanting to slice through the tubers) and gently lift the tubers from underneath, being careful not to stab or bruise them.

• Shake off the soil and admire your little alien-like treasures.

Step 3: Clean Them Up and Dry Them Out

• Brush off excess soil with your hands—don’t wash with water.

• Turn them upside down (stems down) in a dry, airy spot for a week or two. This allows moisture to evaporate and prevents rot. Think airing cupboard, shed, or greenhouse—just not damp and dank!

Important: Label them now while you still remember which is which! Wooden plant labels are the most environmentally friendly and easy to compost after a few years use.

Step 4: How to Store Dahlia Tubers

Once they’re bone-dry, it’s time to tuck them in for winter to ensure they stay dry, cool, dark and protected from mice or moisture, usually in a cardboard box in a shade or car garage for the winter months.

Storage Options:

• In a box with dry compost, sawdust, perlite or vermiculite.

• Each tuber should be cushioned and not touching its neighbour.

• Store in a cool, frost-free place (think garage, shed, or attic). Aim for 4–10°C.

Check them monthly. Remove any that are soft or mouldy—one rotten tuber can turn the whole lot into a horror show.

Step 5: Pot Dahlia Up in Spring

• In March or April, bring them out of storage.

• Pot them up in trays or large pots indoors with multi-purpose compost.

• Water lightly and place somewhere bright and warm.

• As they sprout, you can take cuttings if you fancy more plants for free (yes please!).

Once the frosts have passed in May (depending on your region), harden them off gradually and plant them out again in your border. This is how to ensure your dahlias repeat flower year after year!

Overwintering dahlias isn’t posh or complicated—it’s just a bit of love and storage smarts.

If you’re lazy (no judgement), you can leave them in the ground in very well-drained soil, but mulch heavily and cross your fingers.

I hope that helps!

Lee Garden Ninja