Introduction
Delphiniums are hardy, herbaceous perennials, famous for their tall, bold spikes in rich blues, yellow, purple, pink and white. Delphiniums are members of the Ranunculus family, and are native to the cool mountain meadows of Europe. This makes them suitable for growing as a commercial crop in the Southern regions of New Zealand.
The flowers from commercial Delphinium crops can grow up to 1.5m tall, with the foliage remaining close to the ground. They grow best in full sun with good air circulation. They require protection from the wind either by staking or the use of Flora-Net.
The Nova and F2 Hybrids make up the bulk of the cut flower market and have a vase life of 1–2 weeks. European breeding programmes are trying to extend the harvest season, range of colours and the shelf-life of the crop. Delphiniums are susceptible to a range of fungal problems. Care must be taken with monitoring and spraying.
Growing Delphiniums
| Propagation: | From seed or small cuttings. |
| Time of flowering: | Early summer and then if the temperatures are warm enough another flowering in late autumn. |
| Crop protection: | One layer of Flora-Net is needed to keep the stems upright. |
| Soil type: | Fertile, free draining soils. pH 6.0 – 6.5 |
| Fertilisers: | Nitrogen and potassium are required. |
| Weed control: | Especially at planting, then maintenance weeding after that. |
| Pest/Diseases: | Watch for bacterial diseases, Pythium, Black spot, Powdery mildew, Botrytis, Phytopthora, Thrips |
| Harvesting: | Harvesting of flowers occurs when the first 3-4 florets have opened. Stems are cut and have to be chilled before packing and shipping. |
| Marketing: | Most New Zealand Delphiniums are sold in the USA and South East Asia. |