Dahlia Growing Guide

The History of Dahlias...

Many, many moons ago...1789 to be precise, a number of Dahlias were sent from Mexico (their Native Homeland) to the botanical garden of Madrid, along with the recommendation to use them as food. At the time, this recommendation resulted in little popularity....

All that changed when Joséphine de Beauharnais, Napoleon’s wife, had a sudden whim to fill her entire garden with Dahlias. Having set the new trend, everyone wanted some of these charming beauties in their garden. Dahlias quickly became the 'in' thing, and they soon became rather affordable; their status changed from ‘exclusive’ to ‘ordinary', and for years, the charming Dahlia had to make do with this undeserved status. Fortunately, however, she has been rediscovered! This lady is again a hot item in the garden!

Dahlia Growing Guide

- The best time to plant Dahlias here in NZ is September or October, but can be planted anytime from mid August through to late December.

- Dahlias love sun ,so choose a nice sunny spot in your garden. Ideally a spot that gets at least 4 hours of full sun a day.

- Dahlias will grow in almost any soil, but prefer well drained loamy soil conditions.

- Prepare the ground a few weeks before planting by digging over the soil thoroughly and adding a little well rotted compost and an application of general fertiliser.

- Before planting the tubers, apply stakes (for larger varieties) staking after planting damages roots and tubers.

- Plant your Dahlia tubers about 5-10cm deep and about 50cm apart with the eye facing upwards. Water well and keep moist being careful not to over-water.


After planting...

  • If you're wanting your Dahlia's to bloom like crazy, it's a good idea to pinch out the tops of your dahlia plants after the second set of leaves has developed.... it sounds ruthless I know, but by doing this your Dahlia plant will form four flower stalks instead of one, and will ensure you have a lovely display of blooms for weeks, even Months to come! Either cut them off with a sharp knife, or squeeze between your thumb and forefinger, remove the main shoot down to the top two pair of leaves.
  • Speaking of being ruthless, it's also often recommended to remove all but five shoots sprouting from the tuber. There may be several more shoots, some of them spindly, however all but five should go... this will encourage bushy, vigorous plant growth, with masses of blooms.
  • Earwigs and Slugs can both be a pain when it comes to Dahlias - it's important to keep on top of these wee buggers. Slug bait works a treat for Slugs and Snails, and the eco friendly Neem Granules are fantastic for Earwigs.

Picking Dahlias...

Unlike a lot of Flowering Bulbs, Dahlia Flowers don't continue opening after they have been cut - it's therefore important to only pick blooms that are fully open.

If you don’t manage to pick every bloom for the vase, it’s a good idea to have an occasional deadheading fieldday. Not only will this tidy the bush up, but it  will significantly prolong their flowering, and ensure that more Nutrients head back down into the production of healthy Tubers. 


Alrighty... now you know the ins and outs of Dahlias - time to get gardening!

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