How to prolong the flowering period.
Once the plant has reached about 20cm tall, pinching out the main growing tip to encourage more flowering side shoots. Use a sharp knife or your thumb and forefinger to remove the main shoot (in the centre of the plant, growing upright) down to the top pair of leaves
Tie in the new growth to the stake weekly if possible
Feeding your dahlias with tomato feed, maybe once a fortnight to encourage the flowers to keep coming
When it comes to dahlias, deadheading is the most important task to prolong flowering. Ensure you are removing the spent flower heads and not the new buds, the easiest way to tell is that the buds are more rounded, whereas the spent flower heads are more pointed at the tip. Be sure to remove the whole flowering stem.
What to do with Dahlias over the Winter.
Overwintering in the ground
If you prefer a low maintenance approach to wintering your dahlias, this option may be for you. With recent winters getting milder, it is possible to leave your dahlias in the ground over winter. To do this, you must wait until the Dahlias have become blackened by the first autumn frosts. Then you will need to cut them back to around 10cm off the ground. The next step is to make sure they are deeply mulched to protect them from the frost. (don’t be shy, the more protection the better). If you have multiple dahlias next to each other in a border, it may be wise to label each one as you are cutting them back, so when it comes to spring you know where you are.
If the winter is kind, your dahlias should re-appear in spring, often before the potted plants. Then you will know that you are in for that fantastic display of colour for another year.
Please be aware, that if you do take this option and there is a cold winter, the risk of losing your dahlias completely becomes a strong possibility.
Overwintering by lifting
A much more reliable, all be in time consuming way to ensure your dahlias are protection over the winter months, is to lift them out of the ground and store them under cover. We would certainly advise using this method if the dahlias are planted in a mixed border. If they are mixed with plants that have a strong growth in the spring and the winter, this will cause the dahlias to become over shadowed.
To do this, wait until the autumn frost have blackened the tops, remove all surplus soil including the loose soil around the tuber and cut them down to roughly 15cm and remove them from the ground.
With the time of year, it wouldn’t be sensible to clean the tubers off under a tap. Simply place the tubers upside down or a tray or a crate for a few weeks, allowing them to dry out. Once they are dry, pack them away in a try or a storage box. Ensure that the tubers are surrounded with dry sand or compost or even wrap them in newspaper to stop them from drying out.
Store them in a cool, place that will not get frosted, an attic or a shed will be fine. Make sure that you regularly inspect the tubers throughout winter to ensure there is no rotting.
Troubleshooting with Foliage and Flowers
Leaves and Flowers with irregular holes and pieces eaten away with slime trails present on or near plants = It is likely to be Slugs and Snails, I would say place some Broken eggshells around the bottom of the plant
Leaves with white dust like covering = Powdery Mildew can be treated with a fungal spray from your local garden centre
Leaves, shoots and flowers infested by colonies of black, green or yellow wingless and winged insects; Foliage sticky and sometimes sooty = Aphids or a bug killer spray from your local garden centre
Leaves with irregular holes and pieces eaten away; no slime trails present on or near plants = Caterpillars
Flowers with holes (centre of bloom) and petals with pieces eaten away no slime trails present on or near flower = Caterpillars, remove them from the plant and place them somewhere far away.
Flowers with tattered petals = Earwigs this is simple to fix, Spread petroleum jelly around the stems of your plants