This post is part of our Garden Wisdom from Our Auntie series.
I have a special affinity for Delphiniums, they remind me of my mom and so many of the beautiful gardens I spent time in as a child.
Delphis come in a variety of colours, blues being the most common, also pinks, purples and a lovely pure white. They normally grow to a height of 7 or 8 feet tall and 2 to 3 feet wide. They do best in full sun, but will grow in partial shade.
They are easy to start from seed or plant and pretty much available anywhere. They transplant easily once they are established, and self seed so you will have more to enjoy or share. If they get out of hand in one spot, just dig them out. They are not invasive.
How to Deal with Delphinium Worm
With the beauty, comes some beasts. For this post, I wanted to discuss one of natures most annoying inventions, the Delphinium worm. They also attack monkshood and larkspur.
I have learned through trial and error, and lots of research that the best way to deal with them is by cutting your delphis to the ground, yes, right to the ground in the fall, and disposing of the stalks in the garbage or burn barrel, and never putting them in your compost.
The worms spend the winter in the hollow stems of last years plants and then climb up to feast on new growth. Then the little beasts build a cocoon, curl up for a couple weeks, have a million young’uns, who suck all the moisture and life from your plants, and the cycle repeats.
They especially love to nest in the buds and make it so you have no blossoms if the plant does survive. This is heartbreaking considering it only flowers once per season!
Pick them off as soon as you see the leaves start to curl up, or get blackish, forming their cocoon, and don’t be nice. Crush them and drown them!
There is a biological insecticide called BTK (Bacillus thuringiensis kurstaki – a bacteria found in soil already) that is not dangerous to humans, critters, birds, fish, or honeybees and other helpful insects.
Growing Delphiniums on the Prairies
Delphiniums are best planted in the back of your flowerbeds, preferably up against a fence, and staked to keep them safe when the wind comes shrieking, (and you know it will.) This is Alberta, and the weather is a monster. Mine have already survived our ridiculous May snowstorm and cold snap, two torrential rainstorms, and then 3 days of +30 that fried everything.
I have had incredible luck with delphiniums here in my zone 4 Edmonton garden. My mom grew them in hot, dry, windy Southern Alberta and my sister grew them in Calgary where the summer nights are much cooler. Funny fact, now that my sister gardens in paradise on Vancouver Island they still grow, but they are short, only a foot or so tall, small blossom stalks, but they bloom twice a season.
If you want to grow something that will wow your friends, and make you feel like a badass gardener give these babies a try!
If you have a gardening question you’d like answered, leave a comment below.