October jobs in the Dahlia garden

October is a time for house-keeping your dahlia garden and preparing to lift the tubers.  I am hoping that we can continue cutting for 2/3 weeks into October as the plants are still strong and robust, probably because they had a delayed start.  There is now no need to water the plants.  Look out for the onset of Dahlia Smut; this occurs in cold, damp conditions and appears as paler spots on lower leaves that may spread to all leaves. To control culturally, if at all possible remove all affected leaves.  To control by intervention use a fungicidal spray such as Bordeaux Mixture.  The fungus may lay dormant in the soil so clear away and burn all affected leaves.  However, there should be no long term damage to the tuber if dealt with promptly.

If you have been cutting frequently, as well as dead heading, you will see that stems have the remains of the main shoot and the two primary side shoots, see image 1.  To promote continued strong growth prolonging the flowering season as long as the weather permits these should b, in effect, pruned back.  That is, cut the stem back to the leaf node below that has side shoots showing, See image 2.

Image1: Before pruning back. 

Image 2: after pruning back, the side shoots can be seen by the leaf node.

All plants that are to be discarded should be either removed now or clearly marked to prevent any mix up should they be frosted.  If your bed is to be used for spring bedding it would be time to cut back and lift the tubers in the middle of the month.  However, ideally one can wait until the frost blackens the foliage forcing the sap back into the tuber.  Cut the stems back to 12 / 13 cm before lifting.  Trying to lift before cutting the foliage back may result in the stems splitting and damaging the crown of the tuber.  Label clearly, bring inside and place upside down to drain all the sap out.  

Later in October bring into the greenhouse all pot tubers lying them down on their side to dry off.

Remember to pay your National Dahlia  Society subscription due in November!