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Growing Dahlias


December 6, 2022


Searles Gardening Team

Dahlias are an easy to grow herbaceous perennial plant, which is grown for its magnificent flowers. The blooms can be used as a cut flower that often can last up to a week or be left on the plant to add longterm colour to the garden. The more you cut the flowers off, the more they will produce and be sure to remove all the spent flowers when the blooms have faded.

Some growers thin out the number of buds on the stem, so the fewer flowers they produce are larger than normal.   You see this also with chrysanthemum flowers, especially around Mother’s Day.


Many people buy dahlias as tubers, as these are exact copies of the parent plant and select them for the colour of their blooms.  If grown by seed then there is no guarantee of the colour, form, or size of the flower.  When planted as a tuber they will take about eight to ten weeks to be a mass of flowers.  Always plant your dahlias in a sunny, well drained position, with rich organic matter dug through the soil. Incorporate Searles 5 in 1 Organic Fertiliser when you are preparing the bed for best results. Keep up regular watering once they are growing but also give them a little extra encouragement with Flourish Flowers and Foliage every fortnight to promote more blooms when they are starting to form buds.


When it comes to the end of the season and the plant dies back, you can lift the dahlia tubers and store them in a cool dry place for next year.  This way you will get the same flower colour and form, or you can let them die down and replant with fresh tubers next year.  It is not a guarantee that the tubers will re-sprout if not lifted, as they can be damaged by harsh or wet conditions.


There are a few things to be aware of when growing dahlia; sucking and chewing insects can have a feast on the foliage and the flower and so keep a keen eye out for them.  Fungal issues such as powdery mildew can also occur and a three in one product such as Searles Trifend is handy to keep in the shed. Searles Trifend is an insecticide, miticide and fungicide and will treat most problems dahlias encounter.


To keep dahlias longer as a cut flower be sure to change the water regularly and cut about two centimetres off the stem every time you change the water.  If the stem goes soft and mushy then cut it back to firm stalk and it will last longer.  Dahlia gives a brilliant display of foliage and flowers, with the bonus of becoming a wonderful cut flower. Try planting a few tubers and you will be amazed at the ease of this underrated perennial.