Often delphiniums are thought of as difficult and time consuming to grow. This is not the case. While like all plants, they thrive in ideal conditions, a few basic growing techniques will ensure quality spikes in any garden. At least five hours of sun is recommended.

     Soil: Delphiniums will prosper in almost any soil type. You will want your perennial to last for many years, so amend the soil with compost before planting. Do not allow waterlogged soil, especially in the spring, as this will promote crown rot. If necessary, raise the bed slightly.

    Transplanting: Delphiniums do not like to be disturbed but if necessary move only young  plants and very early in spring, just as they begin to grow.

    Watering: needs to be consistent, especially during the growing season. Delphiniums are shallow rooted but a good soaking once a week should suffice for mature plants. We are on a hill with south exposure and rely on well water, so our watering is minimal. In dry areas, mulch may be beneficial but not directly on the crowns.

    After flowering: cut off the spikes but leave the foliage to promote strong roots. You may be rewarded in autumn with a second flowering but the spikes likely won't be as tall as in July.

    Winter care: Cut off all plant material and clear the beds of debris before winter, to reduce the possibility of slug damage. Delphiniums are very hardy and do not require a winter mulch. They enjoy a good snow cover, if Mother Nature provides it in your area.

Slug and Snail Controls

A thin layer of coarse gritty sand will help discourage these pests year round but be sure it has an open texture and will not form a crust which would affect new growth. Eliminate as many pests as possible by handpicking. Evenings or early mornings are usually most productive for both slugs and snails. In late autumn, cut the stems and foliage of delphiniums to the ground. Remove all leaves, debris and weeds from around the plants as slugs and snails winter over in these. If your garden is heavily infested with slugs and snails, late winter and early spring may be times of excessive damage. A solution of aluminum sulfate (usually 2 oz. mixed in one gallon of water is enough for 4 plants) may be sprayed over the area of dormant delphiniums during the winter. Follow the manufacturer’s instructions for recommended strengths. This solution is astringent and therefore is able to kill adult slugs and snails as well as their eggs. Care must be taken to never spray a plant crown directly unless it is dormant. Aluminum sulfate is a soil acidifier so overuse will change your soil pH and may require an application of lime in the spring.