When growing Delphiniums there are two areas which need particular attention. Firstly, Delphiniums need slug protection. Unfortunately, slugs are fond of Delphiniums, and are especially keen on the new tender shoots which emerge in the spring. It is essential to lay down slug protection. There are lots of ways to defeat slugs, slug traps of beer and pellets are among the most popular. Ideas on how to protect Delphiniums, and your garden, from slugs, how to beat the slugs.
Delphiniums need to be planted in full sun and fertile soil, which is moist, but well drained and most importantly, sheltered from strong winds. Much gardening advice says to water and feed during the growing season; I find if your soil is reasonable that is not really necessary. Delphiniums are hungry feeders, and will definitely benefit from feeding if time allows, but will bloom well without being cosseted. Summer feeding may not be essential, but 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.
All Delphiniums need staking as soon as they have put on growth and are starting to get established, and they need plenty of support. The flower heads can be damaged by heavy summer rain or storms. The blooms become heavy with the rain water and it is hard to stake them enough to prevent the stems from snapping, especially if there are high winds. It is essential to get the supports in place early in the growing season. Delphinium have stems which are hollow and brittle which are easily damaged. It is tricky, when pushing large canes or stakes into the ground next to a delphinium plant, not to damage the delicate stems. There is less risk of damage if the stakes are put in place early. It is also important to use soft ties, and not to tie them too tightly, (which risks damaging the plant stem) and to leave room for the stem to expand with further growth. Run a single can or stake alongside the bloom and using a soft tie link the flower stem to the stake. Alternatively if there is a clump, it maybe easier to make a simple cage out of 2/3/4 stakes, and then use soft ties to link the stems to the supports.
Even with staking it is recommended to plant Delphiniums in a spot sheltered from high winds. Delphiniums bloom best in summers which are calmer with less rain. Check the variety carefully as many Delphiniums can get very tall. Some of the Pacific varieties once established can grow to well over 5ft /1.5m. This means you need stakes or canes which are tall in order to stake the plants.
It is because so many supports are needed for Delphiniums that using natural supports rather than canes looks less intrusive.
If your garden is not sheltered and tends to catch the wind, it maybe more practical to grow the shorter varieties. The colour range is traditionally blue, pink, mauve there are now some yellow Delphiniums and a greater range of colours.