Ask the Expert – Hannah's Dahlia Care Tips

Ask the Expert – Hannah's Dahlia Care Tips

Posted by Amber Williams on 26th Mar 2024

Feeling like it's almost time to plant up your dahlias? Wondering if you're fully prepared for the job? Hannah Rowson, our RHS-certified expert, is our go-to person for planting advice and expert tips. Today, we’re asking her all about dahlias – from how to pot up dahlia tubers to lifting advice.

If you’re planning on getting your dahlias in the garden over the next few months, then keep this blog to hand as a helpful planting guide.

How to Plant Dahlias in Pots

As Hannah always says, any plant can be potted as long as the pot’s big enough. Of course, you can just wait to plant them directly into the border from mid to late May (after the final frost of winter). But, starting them off early is much easier in a container.

“For the best results, we recommend planting one tuber per pot. If you overcrowd them, they don’t do as well.” Hannah tells us.“If you’re putting them in a pot, I’d go for one, and in a decently sized pot for the best results.”.

Hannah explains more about how to pot up dahlias in this TikTok

We also recommend picking a pot with drainage holes, as dahlias hate to be waterlogged. This allows the water to drain out freely. To plant dahlias in pots, follow these tips. 

Step 1 - Fill your pot halfway with multi-purpose compost. 
Step 2 - Put in your tuber with the stem pointing up and the roots pointing down. 
Step 3 - Cover with compost with the stalk just below soil level. 
Step 4 - Water them every day, especially in warm weather or when the soil is dry to the touch. 
Step 5 - Gradually acclimate the dahlias outside from mid to late May, once the threat of frost has passed. You can then replant the tubers (gently) or keep them in your pot for a container display. 

How to Pinch Out Dahlia Tubers

You can double or even triple your dahlia blooms by pinching them out, and when you’re growing a large display of dahlias, it’s certainly worthwhile as it will produce a fuller display.

Hannah explained in a recent TikTok “The reason that you would pinch out your dahlias is to get a bushier, less leggy plant that produces way more flowers. Ideally, you'll want to do it when it's over 20 cm in height.” She then described her method of pinching out dahlias “Look for a set of leaves where the side shoots come in, so what I'll do is I'll just take some sharp secateurs and I'll just cut off the main stem just above these side shoots”.

What to Do with Dahlias Once They’ve Finished Flowering

Early autumn is the perfect time to care for your dahlias as they die back. This includes giving them time to die back completely, lifting them, and storing them over winter.

Hannah gives us her top dahlia care tips in a recent TikTok on how to care for dahlias “When they start to die back, all the foliage will start to go yellow, and it will all fall over. After it’s done that, it’s important to lift them. But if you do it too soon, there won’t be enough nutrients that’s been brought back into the tuber and your dahlias won’t be as good next year. You need to wait for that to happen before you lift them.

How do you store tubers? Hannah answers this too; “You can cut this year’s growth off, lift them out of the ground, and then store them. The best place to store them is in a cool dark place like a shed or a garage. You need to allow them to completely dry out, so it’s recommended you either store them in paper bags to keep any moisture out or in big tubs filled with sawdust. Keep them completely dark throughout winter and in spring once the frost has passed you can then replant them for dahlias in the summer.”.

Follow Hannah's top dahlia tips to keep them in the best possible shape for the following year. Want to ask Hannah a question? Follow us on TikTokInstagram, or Facebook and drop us a comment or message.