You may have seen a patch of wild lupines (Lupinus spp.) on an early summer drive up the California coast or a hike through the hills of southwest Texas. From a distance, they look like large waves of blue, purple, or white rolling gently in the breeze. If you roll your windows down, you may even get a whiff of their light, sweet scent. If you’ve wondered about growing them in your own garden, it’s useful to know if they can handle your conditions. Should lupines be planted in sun or shade?
When viewed up close, lupine flowers in all settings reveal themselves as members of the pea family (Fabaceae) by possessing a spikey, complex flower head with whorls of tiny, shell-like flowers. They range in height from 1 to 4 feet and have palm-like foliage that radiates outward like a hand. Flower heads can be anywhere from 4 to 12 inches tall. Cultivars come in widely varied colors, such as pink, red, orange, and yellow, but their basic structure is the same as their wild cousins.
Because members of the Lupinus genus can be wild or domesticated and perennial or annual, their preferences, hardiness zones, and growth habits are quite diverse. Some species have a high tolerance for afternoon heat, while others demand shade late in the day. Some flower in partial shade while others shut down completely. These variations can make site selection challenging, even for the most seasoned gardeners.
So, do lupines need full sun, partial shade, or full shade to thrive? To answer this question, let’s examine the plant’s basic exposure preferences, discuss the nuances of the three sun categories, and propose locations that will meet the needs of some specific species.
The Short Answer
Both annual and perennial lupines require full sun. This means they should be exposed to direct light for a minimum of 6 hours per day, with 8 hours being preferable.
The Long Answer
Lupines in both wild and domestic locations will flower to their fullest potential when planted in full sun, but that doesn’t mean they can’t live with less. They may also wilt under the concentrated rays in the afternoon.
With that in mind, deciding where to plant lupines can be confusing. To help you choose a location on your property where your lupines will thrive, let’s look at the exposure categories as they relate to the Lupinus genus and suggest some species or varieties that may do well in varying light conditions.
This exposure level applies to any location receiving at least 6 hours of direct sunlight daily, but 8 hours is more consistently viewed as full sun conditions. It’s important to note that the hours need not be consecutive. A lupine that gets 4 hours in the morning before the sun moves behind a mature tree will be okay if it gets another 2-4 hours before sundown.
As long as the hours add up to at least 6, a location is in full sun. However, most lupines prefer 8 hours of direct sunlight for the best flower development.
Draw a Garden Map
Make a simple garden map to determine if a potential location has full sun exposure. It’s easy to do and can be an eye-opening exercise. Here’s how:
- Draw a rough sketch of the area where you plan on planting lupines.
- Begin at 7 a.m. and set a timer to go off every hour until sunset.
- Go outside each hour and make a hashtag every time the bed is exposed to unimpeded sunshine.
- Total your hashtags.
- If the number is above 6, you’ve got full sun!
Can Lupines Get Too Much Sun?
Your lupine will receive enough sun in an open field with no trees or structures to diffuse or block direct light. But could they be getting too much? It depends.
Wild lupine species that thrive in open, untended areas will not suffer the effects of excessive heat and sun. Texas bluebonnets (Lupinus texensis), tree lupine (Lupinus arboreus), bicolor lupine (Lupinus bicolor), and Arroyo lupine (Lupinus succulentus) can soak up a full day’s worth of rays and not suffer any effects.
On the other hand, lupine hybrids developed for ornamental use are typically cool-climate plants with a little more fragility. Most cultivars in the Russell hybrid family and those from the English hybrid family will droop in the afternoon heat. To protect them from heat stress, plant them where a mature tree, shrub, or building will screen the sun as it moves west in the afternoon. Typically, a couple of hours of afternoon shade during the day’s peak heat is ideal.
Botanically speaking, this exposure level applies to locations that receive between 4 and 6 hours of sun daily. If a plant tag indicates a preference for partial shade, assume the species has some heat sensitivity. It will do best if rays are concentrated in the morning hours.
Lupines are typically tagged as full sun or full sun to partial shade plants at your local nursery or in a seed catalog. Different varieties can be grown successfully in either exposure, but think about it like this: lupines will flower best and have the highest resistance to disease with morning sun. If that’s not an option, a site with partial shade is the next best thing.
What about Dappled Sun?
This is where things get tricky for lupines. In a bed located beneath a mature tree with a loose canopy, lupines may be getting dappled sun all day long. You might wonder if the exposure adds up to 6 hours a day, or at least 4, and if you can grow lupine in that location. Unfortunately, that’s a really good question without a definite answer.
A lot depends on the intensity of the sunlight that reaches the earth through the canopy. Try visiting the site several times throughout the day as the sun arcs over your property to assess the level of heat that breaks through. It might be worth a try if you can feel the sun’s warmth most of the time.
Again, full sun is ideal. Partial shade is acceptable. In locations with dappled light, be prepared for less-than-perfect blooms and look for shade-related issues such as powdery mildew and slug damage.
This exposure level applies to a site with 4 or fewer hours of direct sunlight per day. Rays may be concentrated in the morning or afternoon and may be either direct or indirect (dappled).
Lupines planted in full shade are not likely to flower and may suffer from excess darkness and moisture issues. If a location with full shade is your only option, skip the lupines and go for hosta, heuchera, or ferns.
Lupines will be happiest and healthiest in locations with full sun. Wild lupines, in both annual and perennial form, do not need protection from late-day rays, but backyard hybrids do, especially in warmer hardiness zones. If you’re forced to choose between full sun with hot afternoons and partial shade with late-day protection, it’s safest to go with the latter.