If you don’t have a garden, or wish to grow your dahlias on a balcony or in a paved courtyard you will want to grow them in pots. You can grow dahlias in pots, it is a matter of choosing the right dahlia and the right pot.
Some dahlias grow more vigorously than others, it is the smaller growing types that are best suited to growing pots. Invariably, the root system is smaller when growing in pots, this means that the plants are a little less stable and subject damage and falling over. So taller growing types will need lots of support.
The lower growing types such as Dahlia Mystic Illusion will need very little or no support.
The pot that you choose needs to be reasonably large to allow for the tuber to grow as well as the root system. A 300mm (12 inch) container is a minimum for good growth. You also need to make sure that the pot or container has good drainage holes, dahlias do not like wet soggy soils.
Dahlias are perennials, so with proper care you can grow them in pots and they will come back year after year.
How to plant Dahlias in pots
Dahlias are hungry plants, they do like a rich soil. Use a good quality potting mix, perhaps with some added compost also add around 2 cups of aged cow manure to the potting mix.
The dahlia tuber or bulb is planted in the normal manner. The tuber is planted at around 10 cm (4 inches) deep. The eye, which is near the neck of the tuber is slightly higher than the rest of the tuber.
Once the plant sends up shoots, mulch around the plant in the container, this will keep the moisture level higher and the root system cooler.
General care for dahlias in pots.
- Dahlias require a frost free position.
- Put the stake in before the tuber to avoid damaging the tuber, or use 3 stakes around the edge of the pot.
- Keep the plant moist.
- A position in moving sun and afternoon shade is best. You can use a 50% – 70% shade cloth.
- Ensure that drainage is good.
- Fertilise regularly, avoiding high nitrogen fertilisers as this will promote foliage growth rather than flowers.
- Apply a small amount of sulphate of potash to promote flowering.
- Foliar spray with epsom salts for stronger plants and flowers.
- Deadhead dahlia after flowering to produce more blooms.
Once the foliage dies back, remove the tubers from the pots, place them in a cool dry position indoors over winter. They will be ready to plant out once the danger frosts is over in spring. You can try leaving the tuber in the container over winter as long as it is under cover and the soil remains close to dry.
In milder climates potted dahlias can remain in pots over winter as long as the drainage is good.
- When buying dahlias for growing in pots, look for the smaller growing types.