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How To Grow Dahlias : Growing Dahlias In Pots

Tips on how to grow dahlias in pots from tubers and cuttings including watering, fertilizer and pruning are given with pictures. Dahlias belong to the family Asteraceae, a part of the daisy family. They are hard to beat for dramatic display of colours in summer and autumn. Dahlias are named after the Swedish botanist, Dr Anders Dahl. There are about 30 species of Dahlia.


Ball Type Dahlia
Ball Type Dahlia
As most varieties of dahlias grow tall and need to be staked, many gardens do not like to grow this plant. In Australia and the World over, dwarf dahlia varieties are now been planted and use green color stakes to blend in with the garden.

There are hundreds of different cultivars and hybrids of dahlias. The colorful spiky flowers bloom from summer to the early winter. They come in many shades - Red, Pink, Orange, Yellow, Purple, White and one nearly black, and there are bi-colour ones as well. The flowers range in size, from 2 inch to the giant 10-inch blooms.

Dahlia Growing Information

  1. Position: Select a planting site with full sun, protected from wind. Dahlias grow more blooms with 6 to 8 hours of direct sunlight. They love the morning sun and afternoon shade.
  2. Soil for Dahlias: Dahlias thrive in humus-rich, well drained soil so add some peat moss or compost or composted cow and sheep manure to loosen the soil texture for better drainage as explained in garden soil preparation. Soil should be slightly acidic, pH about 6.5-7.0.
  3. If potted in containers, the pot should be 12 inch x 14 inch.
  4. Plant tubers in the mid spring when the soil temperature is on the rise and the risk of frost is over. Do not cut individual dahlia tubers as you would potatoes. Select dahlia tubers that do not appear wrinkled or rotten.
  5. It is better to plant the smaller tuber because it will develop its own root system quicker than the big tuber. The big tuber develops its root system much later.
  6. For the taller dahlias, insert stakes at planting time. Plant the tuber whole about 6 to 8 inches deep, with the growing eyes," facing up, space about 18 to 24 inches apart, and then cover with soil. Do not water after planting, it can cause tubers to rot.
  7. Watering: Water when the sprouts have appeared above the soil. Give a deep watering 2 to 3 times a week for at least 30 minutes with a sprinkler if planted in ground bed, otherwise more frequent water is needed for plants in containers. Application of mulch is good for water retention and reduce evaporation. The mulch also assists with weed control further reducing evaporation.
  8. Fertilization: Dahlias benefit from a low-nitrogen liquid fertilizer such as a 5-10-10. Fertilize after sprouting and then every 3 to 4 weeks from mid-summer until early Autumn. Do  not over fertilize with nitrogen to avoid small or no blooms.
  9. When the flower season is over, cut back and leave in the ground; cover with a deep, dry mulch. In cold regions, you can dig out the tuberous, wash and dry them in shade and store them for the next season.
  10. Pests: Put slugs and snails bait 2 weeks after planting and continue to bait throughout the season.
  11. Pruning: Pinch the growing shoot just above the third set of leaves to encourage bushiness. (The shoot can be potted in course sand which will grow into an individual plant.)
  12. Cut Flowers: When you cut flowers for inside, cut at least two sets of leaves, that will encourage more prolific new growth. If not cutting blooms, be sure to regularly prune the spent flowers. The best time to pick flowers is early morning. Put them into the water ASAP. Make the cut is at an angle. Continue dead-heading to ensure the Dahlias to bloom for a long time.
Double Dahlia Tubers
Double Dahlia Tubers
Dahlias growing in a pot
Dahlias growing in a pot