How To Grow Delphinium Flowers From Seed

Germination Tips 

• Delphinium seeds can be sown in autumn and spring. See our seed sowing chart to work out when is best in your climate here.
• As with most seed starting, I would raise seedlings over direct sowing in a greenhouse. 
• Press the seeds on top of the soil and then make sure the seeds are covered lightly with soil, they will need darkness to germinate. I then like to put a layer of vermiculite to keep the moisture in. 
• Germination takes around 10-20 days at 18-21 degrees, they do prefer cooler germination temperatures. 

Planting Tips

• Once the seedling has reached around 6-8 weeks of growth and has two sets of leaves, it is time to harden the seedlings off. Do this by putting the seedling outside for a few hours on the first day, gradually working up to a full day to prevent any transplant shock.
• Delphiniums will enjoy well draining, rich with organic matter soil - soil prep is key! 
• When deciding on where to plant them out in the garden, choose a full sun - part shade position that is protected from the wind.
• Delphinium can grow up to 180cm, so netting support may be required. There are also dwarf varieties, such as pink butterfly that does not need support.
• Space 30-40cm apart.
• A treatment of liquid seaweed every few weeks will encourage strong growth.
• Slug and snails love delphinium seedlings, so make sure they are well protected from these pests.

Harvesting Tips

• Delphinium take around 150 days from seed to bloom.
• When 1/4 to 1/3 of flowers on stem are open. Place immediately in water.

Please note 

All parts of this plant are poisonous, including the seeds.