What’s it like to have more than 50 delphiniums in bloom in your garden? Sweet. Follow the story of a new kind of delphinium, from seed to bloom in 15 months.
Slide Show: New Millennium delphiniums, from seed to bloom. Click on the images to see captions or go to full-screen mode.

A little over a year ago, I wrote about my intentions to start some delphinium seeds that I’d ordered from Dowdeswell’s Delphiniums in New Zealand. Terry Dowdeswell has bred a new and more vigorous strain of delphiniums, which he christened New Millennium. This new strain of plants first became available in the U.S. market in 2008, but only a few of the varieties are available — and at a dear price.

New Millennium delphiniums growing in raised beds at Sue’s house.

So my gardening friend Sue and I decided to grow our own. She’d pay for the seeds and I’d start the seedlings in my greenhouse. In April 2008, I sowed the four little packets of seeds in 4×6 flats. To my surprise, nearly every seed germinated!

About a month later the plants were ready to be moved into 6-packs. At this point I also moved them out of the house (where they’d been growing under lights) and into the greenhouse, where they stayed for another month or so.

By late June, the plants were starting to get crowded in the 6-packs. At that point, my partner in this delphinium project took home her half of the plants. This left me with about 80 seedlings, which I transplanted from the 6-packs into 4„ pots.

The 6-packs Sue took home were planted directly into her garden. But in my own garden, there wasn’t an inch of free space available. Nothing to do but wait until fall when crops started coming out of the vegetable garden. It was around this time that it began to dawn on me that I would never have room for a dozen delphiniums — much less 80!

By late last fall, I made a space in the vegetable garden where the plants could winter over. All 80 plants were transferred from their pots into the garden. In early December, they got covered with a 10- to 12-inch layer of straw for insulation from our zone 4 winter.

This spring, once the ground had thawed, I moved about 30 of the plants into my cutting garden. Another dozen went into the back of my long perennial border (of course I first had to make room for them by removing 10 gigantic clumps of Siberian iris). The rest of the delphiniums were potted up into 1- or 2-gallon pots and went home with various friends.

Now it’s early July and my New Millennium delphiniums are 15 months old. They’re beginning to bloom for the first time and they look fantastic.

But here’s something interesting: The plants that stayed at my house are half the size of the ones that went to Sue’s. I suppose this could be just a difference in the color of our thumbs. But it could also be a discovery that young delphinium plants ought to be transplanted into the garden as soon as possible. Keeping them in small pots for the summer arrested their development and delayed flower production for a full season.

So what’s it like to have 60 or 70 delphiniums in your garden? Sue tells me that they’ve cost her many sleepless nights. When it rains or the wind begins to blow, she lies in bed fretting about whether she has staked the plants well enough, or if she should maybe go out there with an umbrella to protect them. Her intricate support system of wood and rebar stakes, sections of reinforcing wire held horizontally, and lots of twine will hopefully help them to withstand the inevitable late-summer thunderstorm.

Neither of us can quite believe how lucky we are to have such an extravagance of flowers in our gardens. However fleeting this experience may be, we did it. We grew some beautiful delphiniums from seed and got to see them bloom in our gardens.

Kathy LaLiberte, Director of Gardening, Gardener’s Supply