Delphiniums

One of the most spectacular perennials to adorn Pacific Northwest gardens is the Delphinium. Very few gardeners in the nation can grow delphiniums as perennials and treat them as annuals. They do best in regions with cool summer nights and low humidity.  They are well-suited for the Pacific Northwest but resent periods of high temperatures and humidity. Needless to say, they are not going to like this coming week!

The towering spikes of delphinium flowers (growing up to 6 feet tall) are good candidates for the back of the border. Flower colors come in blue, purple, red, white and pink. For the most dramatic impact, plant in groupings.

Grow delphiniums in deep, rich, moist soil generously ammended with compost in full sun to partial shade. Mulch with compost and apply several times during the growing season. Delphiniums are heavy feeders so feed regularly (every 4-6 weeks) with an organic fertilizer such as fish emulsion or any well-balanced fertilizer. Superphosphate is also a good fertilizer to add to the soil when planting. Yellowing leaves is an indication that they need more fertilization.

Keep faded blooms deadheaded to keep the flowers coming. After the plant has finished blooming, cut the stalks back. You should get more flowers later in the summer.

Since delphiniums grow so tall, staking is advised. To avoid damaging or breaking the stems, it is good to install stakes when you plant.

Slugs are often a problem. These pests can be combated with slug control or Diatomaceous Earth.