Greetings from the lupine community! We are a diverse genus, *Lupinus*, with many species calling the United States home. Our blooming schedule is not a single date but a rolling wave of color, dictated by our genetic programming and a deep, instinctual response to environmental cues. To understand when we typically display our magnificent flower spikes, one must consider both our geographic location and our specific species.
Our internal clocks are set by the length of daylight, a phenomenon you know as photoperiod. Most lupine species are "long-day" plants. This means our flowering mechanism is triggered as the days grow longer after the spring equinox. Furthermore, many of us require a period of cold dormancy, called vernalization. This chilling period satisfies a biological requirement, ensuring we do not attempt to bloom before the danger of a severe frost has passed. It resets our system, priming us for robust growth and flowering when warmer temperatures and longer days arrive.
The vast climatic differences across the continent mean our bloom time varies significantly by region.
In the Pacific Northwest and West Coast, species like *Lupinus polyphyllus* (Bigleaf Lupine) and *Lupinus arboreus* (Yellow Bush Lupine) begin our show. We typically start sending up flower spikes in the late spring, with peak blooming occurring from May through July. The cool, moist springs here are ideal for our growth cycle.
In the South and Southeast, the season starts much earlier. Here, you will find species like *Lupinus diffusus* (Sky-blue Lupine) and *Lupinus perennis* (Sundial Lupine). We take advantage of the milder winters and often begin flowering as early as March, with blooms continuing through April and into May. We must complete our reproductive cycle before the intense summer heat and humidity set in.
In the Northeast and Great Lakes regions, *Lupinus perennis* is also a common native. Our schedule here is later due to the colder, longer winters. We emerge later in the spring and typically do not open our flowers until late May or early June, often blooming throughout the month of June.
In the high-altitude regions of the Rocky Mountains and the West, species like *Lupinus argenteus* (Silvery Lupine) have a very compressed growing season. Our bloom is entirely dependent on the snowmelt. We may not even emerge from the soil until June or July, flowering quickly in mid to late summer to set seed before the first autumn snows fall.
It is also important to mention the Russell Hybrids and other garden cultivars bred from our wild cousins. These cultivated forms are selected for specific traits and often have more flexible blooming schedules. In many gardens, with adequate moisture and care, we can be encouraged to produce a primary flush of blooms in late spring to early summer (June). If spent flower spikes are removed, many of us will often reward the gardener with a second, smaller showing of blooms later in the summer or early fall.
