From our perspective as a plant, the term "full sun" is a broad and often harsh human classification. Our species, *Lamprocapnos spectabilis* (formerly *Dicentra spectabilis*), evolved in the cool, moist understories of woodland areas in Asia. Our very physiology is built for an environment filtered through the canopy of taller trees. We thrive in what you would call partial to full shade. This is our home, our comfort zone, where our metabolic processes—particularly photosynthesis and transpiration—operate at their ideal, gentle pace without the stress of intense solar radiation.
When planted in full sun, we face significant physiological challenges. Our delicate, fern-like foliage is not equipped with the same waxy cuticles or sun-reflecting adaptations as true sun-worshippers. The primary issue is excessive transpiration. The intense heat and light cause us to lose water through our leaves much faster than our roots can absorb it from the soil. This leads to wilting, scorching of leaf margins (a condition akin to a sunburn), and a general state of heat stress. Our growth becomes stunted as we divert energy from producing our iconic heart-shaped flowers to simply surviving the daily onslaught.
Our ability to tolerate a sunnier location is almost entirely contingent on one factor: consistent and abundant soil moisture. If our roots are kept perpetually cool and moist in a rich, humus-heavy soil that retains water like a sponge, we can manage the higher rates of water loss. However, this is a precarious balance. Even a short period of drought in full sun will cause rapid decline. Furthermore, our fleshy root systems are susceptible to rot if the soil is both waterlogged and warm, creating a contradictory set of demands that is very difficult for a gardener to maintain.
Our tolerance for sun is not absolute; it is heavily influenced by your local climate. In cooler northern zones or regions with consistently cloudy, cool summers, we can perform reasonably well in a location that receives several hours of morning sun. The gentle morning light is far less damaging than the intense, hot afternoon sun. However, in warmer southern climates or areas with intense summer heat, full sun is almost always a death sentence, or at the very least, will ensure we die back and go dormant much earlier in the summer, cutting our beautiful display short.
To see us at our best—with lush blue-green foliage and long, arching stems laden with flowers—the ideal is to replicate our native woodland conditions. Planting us on the north or east side of a structure or under the light shade of a deciduous tree provides the perfect compromise. This offers us the bright, indirect light we need for photosynthesis and flowering while protecting us from the harshest rays of the midday and afternoon sun. This is where we are truly happy and can focus our energy on growth and reproduction rather than mere survival.
