Dahlias have rather been enjoying these warm, wet weeks and have continued to perform extravagantly in the Cutting Garden at Petersham Nurseries. A rich soil and the care and attention of Rosie Bines and her team have obviously been key – plus they have been regularly harvested so that new blooms just keep coming. Here is just a selection.

We’ll be lifting the tubers after the first frosts blacken the top growth – and that might be any time in the next month – it is important to let that first frost do its work so that the plant knows to stop growing.

The top growth will be cut back to a few cm above ground and the tubers lifted, the soil brushed carefully off and left to air dry for a few days before being then potted up (and labelled) in dry compost in large 10L plastic pots to be stored for the winter. You might place them between crumpled newspaper and store them in the shed or garage, or under the spare bed. You might dust them with a proprietary fungicide before putting them to – or under – the bed. Zealots might clean the tubers thoroughly before, dry, tightly wrapping individual tubers in cling film before storing them in a cool, dark place. Crumpled newspaper has always served me well.

Check them once every month for rot and remove any soft or discoloured material. The growing process can start again next year – and you might divide the tubers before you do – under protection next March or straight outdoors after the last chance of frost has passed directly into the garden in May.

And here’s that Liquidamber, the rich background to the image above …


The National Dahlia Collection in Cornwall


The National Dahlia Society


Rose Cottage Plants – who have an extensive collection for sale in season