Delphiniums are an impressive border plant with tall spires of flowers which bloom in mid-summer. I grow them I love them, but they are hard work and definitely a red wheelbarrow plant.
Delphiniums are a hardy herbaceous perennial, which means they are tolerant of our winters hardy down to H5, (explanation of frost hardy.) In late autumn and winter they die back completely to bare earth and re grow each spring.
Delphiniums need moist good fertile soil and are best planted in a sheltered spot way from winds. Delphiniums fare best in summers which are cooler, hot dry summers are not ideal, causing the Delphiniums to tend towards powdery mildew. Although Delphiniums need sun, they are best not planted in garden hot spot. Ensure that plenty of organic matter or compost is worked into the planting area and plant the delphinium level with the existing soil, i e not too deep. Given the heavy flower heads supported by hollow stems, gusty winds and rain are not ideal either. Still in the right conditions during the right summer they can look just fabulous.
Much gardening advice says to water and feed during the growing season; I find if the soil is reasonable that is not really necessary to feed them. Delphiniums are hungry feeders, and will benefit from feeding if time allows, but will bloom well without being cosseted. Whilst summer feeding may not be essential, staking is. Which means if you don't have time to feed and stake Delphiniums, the more important task is to stake them so the plant and blooms are well supported.
After flowering, it is best to dead head the flower spike, and further smaller flower shoots should appear. Bees are attracted to Delphiniums drawn in part by their lovely strong blue, as bees do love blue flowers.Delphiniums are a red wheelbarrow plant as they need quite a lot of attention in terms of slug protection, staking and if time allows, feeding, as detailed below. If Delphiniums are not your first choice to plant check out summer flowering plants, scented plants and climbing plants for more ideas on what to plant in the garden.