How To Grow Dahlia From Seed
​
Dahlia seeds do not require any treatment (eg soaking, stratification) before sowing.
Dahlia seeds can be sown directly into the garden OR seedlings can be raised in trays or other containers and transplanted to the garden once established.
Sow Direct
-
Sow seeds directly in the garden 10mm deep and 30-45cm apart.
-
Keep soil moist but never wet or dry.
-
Seeds should germinate in around 3-5 days at a soil temperature of 18-21°C.
-
Young seedlings will need protection from pests, pets and weather until they are established.
Raise Seedlings
-
Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
-
Sow seeds 10mm deep.
-
Keep soil moist but never wet or dry.
-
Seeds should germinate in around 3-5 days at a soil temperature of 18-21°C.
-
Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
-
Plant out, spacing plants 30-45cm apart.
Dahlia is a tender crop that’s sensitive to frost. Do not transplant seedlings or sow seeds outside until all danger of frost has passed.
Optional: In cool climates dahlia seeds can be sown indoors 6 weeks before the last expected frost. Grow them in a warm position with plenty of natural light.
​
How to Grow Dahlia
Dahlia plants may need watering during the growing season. Water when the soil is dry about 5cm below the surface (test this by scratching away a little soil with your finger). Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases.
​
If soil was well prepared no extra fertiliser should be necessary. In poor soil or to give your plants an extra boost, application of a high-potassium fertiliser or one formulated for flowering plants can be beneficial:
-
Apply slow release fertiliser at the recommended rate when transplanting or when seedlings are 5-10cm tall.
-
Apply liquid fertiliser at the recommended rate and frequency while plants are fruiting or flowering.
Dahlia plants may need to be supported as they grow. Depending on the expected size and height of the plant, use a stake, bamboo cane, trellis or string lines to support plants. Make sure you have the support in place when you sow seed or transplant seedlings to avoid disturbing the plant's roots later.
Optional: Pinch out the growing tips of dahlia plants to encourage denser growth with stronger stems and more flowers. Using sharp secateurs or snips remove the top set of leaves, cutting just above a set of lower leaves.
Dahlia plants should flower in approximately 110-130 days.
Deadhead dahlia flowers regularly during the growing season. Using sharp secateurs or snips cut fading or dead flowers off just above a set of leaves. Removing old flowers regularly will encourage plants to produce more flowers.
​
CHECK OUT OUR VIDEO HOW TO GROW FROM SEED
​
​
​
​
​
​
​
