How To Grow Dahlias
Here are our answers to the most commonly asked questions about successfully growing dahlias:
What is the best location in a garden to grow Dahlias?
Dahlias grow almost anywhere, but thrive when they receive morning sun and afternoon shade. For best results, ensure the plants are sheltered from the wind and are in an area with good drainage.
When is the best time to plant Dahlias?
Plant from late September through to middle to late December. Dahlias do not tolerate frost so avoid planting if the weather is still too cold.
How do I prepare the soil?
To increase the levels of organic matter in the soil, it is a good idea to grow a green crop (such as wheat, oats or legumes) that is dug in prior to planting. About 2 weeks prior to planting the tubers, incorporate animal manure (sheep or cow) and chemical fertiliser. We recommend using the growth enhancers NGI and Wormhit, which we supply. Pig or poultry manures may be used, but they should be well rotted or broken down as they are otherwise too strong and can inhibit growth of the plants.
How much room does each plant need?
Leave about 600mm between each tuber, although shorter varieties may be planted closer together. Plan for rows to be 900-1500mm apart.
How do I plant tubers?
- Dig a hole about 10cm deep.
- Put the tuber in the hole with the eyes facing up.
- Fill the hole with enough soil to just cover the top of the tuber.
Do I need to stake the plants?
The plants need to be supported by either stakes or a trellis. If using stakes, position these before planting the tuber so that the stakes do not damage the tuber when they are inserted into the ground. If using a trellis, ensure that the first wire is 20-30cm from the ground and wires above that may then be 30cm apart.
Can Dahlias be planted amongst other plants?
They may successfully grow amongst other plants such as small shrubs and roses.
How often should I water after planting?
It is not necessary to water the tubers as soon as they are planted unless the weather has been particularly dry. Water the plants if rainfall has been less than 25mm in the last 7 days and water early in the morning.
Plants can do very well with a dripper system. A pulse watering system is effective and involves the application of a small amount of water 4 times a day for approximately 2 minutes at a time. Mulch is helpful in reducing evaporation and controlling weeds.
How do I care for the plant once it starts growing?
As the plants start to grow, remove any damaged foliage and if necessary, remove lower leaves to ensure that there is enough air circulating around the base of the plants.
How do I get maximum blooms throughout the season?
For more blooms, remove the growing tip once the plant is 30-40cm tall. Keeping up with dead-heading will assist plants with blooming for a long period.
What is the best time to pick the blooms?
Pick blooms first thing in the morning and place them in water immediately.
Can I grow Dahlias in pots?
Yes you can! Dahlias in pots require more regular watering than those planted in the ground. Fill a 300mm pot with potting mix and a couple of handfuls of manure for best results.
Do I need to protect the plants from pests?
It is advisable to use an insecticide to protect plants from thrips and aphids.
Keep snails and slugs away with snail bait.
Use a miticide to protect the plants from mites.
Should I lift the tubers each year?
Tubers may be left in the ground for approximately 2 seasons, but after that it is advisable to lift them from the ground and divide them.
If there is a chance of frost, lift them and store them so that they are protected from frost.
