What Is Blue Lupine?
Identification: What Does the Plant Look Like?
Spiky blue flower racemes (4-10 inches tall), which bloom in late spring or early summer, are the hallmark of this perennial, which can grow as high as 2 feet.
It is smaller than its introduced rival, Lupinus polyphyllus (see below). Of this lupine's foliage, Lawrence Newcomb, in his wildflower identification guide, writes, "Lower leaves with 7-11 leaflets 1-2 inches long." Because of the appearance of these palmate leaves, the plant is moderately attractive even when not blooming.
Planting, Preferred Growing Conditions
Lupines, having long taproots, are one of those fussy plants that dislike being transplanted. For this reason, it is better to try to establish them by seeding.
Allan Armitage, in his book on garden perennials, observes that lupine flowers "love the cool weather, hate the combination of heat and humidity...." (p.198). That's why, although blue lupine is listed by many authors for planting zones 3-9, that range is probably somewhat deceiving. It may technically grow as far south as zone 9, but it will perform better in the more northerly reaches of that range.
Our Flowers Expert, Jamie McIntosh, furnishes a more realistic listing of zones 3-7 for Lupinus species.
Keeping in mind this perennial's hatred for heat and humidity, you'll better understand my recommendations regarding light conditions. In the North, locate blue lupine flowers in full sun. The further south in its range you go, the more it makes sense to grow it in partial shade.
Provide your plants with a well-drained soil, leaning toward the acidic side in terms of soil pH. Due to their nitrogen-fixing ability, they don't need you to supply them with a lot of nutrients; in that sense, they're not fussy. But they are, indeed, fussy about the drainage requirement, so if you have a clayey soil, make it more friable by working in some humus.
"Wild" Is Not Synonymous With "Native"
My wife and I live in southern New England. But we vacation frequently in northern New England. Lupine grows wild all over up there. You can't miss it in spring when it blooms. Maine, New Hampshire, and Vermont even celebrate lupine festivals. New Hampshire's (held in Sugar Hill, in the White Mountains) is the best known of these.
Once, while vacationing in New Hampshire's White Mountains, we went on a wildflower walk led by a woman I have dubbed Wildflower Wilma elsewhere. I was enjoying chatting with Wilma about all the wild plants we were encountering, so I thought it was the most natural thing in the world to mention that I had been admiring the large stands of lupine in mixed colors that line the roadsides of northern New England. I was caught off-guard by her response, which indicated a disdain for the lupines with which I had so fallen in love.
So what could someone who leads wildflower walks possibly have against such a beautiful wildflower (in this case, a species known as Lupinus polyphyllus)? Well, the answer lies in the fact that not all wild plants are native plants, and the beauties that had so enthralled me actually were not indigenous to New Hampshire. This alien lupine had the gall to hail from western North America. As it turned out, Wilma was not so much a wildflower enthusiast as she was a native plants enthusiast.
It is blue lupine (Lupinus perennis) that is native to eastern North America (including New England).
Other Types of Lupine
In addition to Lupinus perennis (i.e., the blue lupine that is the subject of the present article) and Lupinus polyphyllus, the pretty but unwelcome guest at Wilma's Granite State party, I'll mention two other kinds of lupine here:
- Texas bluebonnets (Lupinus texensis)
- The Russell hybrids (a hugely popular commercial version of Lupinus polyphyllus)
The Karner Blue Butterfly Connection
You butterfly aficionados may have heard of the Karner blue butterfly (Lycaeides melissa samuelis). The Michigan Department of Natural Resources (MDNR) reports that it is on the federal government's endangered species list. MDNR goes on to say that its larvae feed only on blue lupine leaves and flowers. The reduction in the population of Karner blues is directly correlated to the dwindling numbers of blue lupines across much of their native range.
Curious Fact: The Phenomenon of the Incredible Exploding Seed Pods
You may have heard that as the seed pods of lupines dry out, they explode, ejecting the seeds. Is this myth or fact?
It is fact. Lupines are among the plants that set off explosions, so to speak, as a means of dispersing their seeds more broadly. Other plants that reproduce explosively include:
- Wisteria vines, which are also in the pea family
- Impatiens, especially the hardy impatiens known as "jewelweed" that grows wild across much of North America