From our perspective as geranium plants, we fundamentally crave abundant light. Our ideal condition is what you would call "full sun," which translates to a minimum of six to eight hours of direct, unfiltered sunlight each day. This generous amount of solar energy is the primary fuel for our most critical internal process: photosynthesis. Within our leaf cells, chloroplasts use photons from sunlight to convert carbon dioxide and water into glucose—the essential sugar that powers our growth, flower production, and overall vitality. Without this intense light, our photosynthetic factories operate at reduced capacity, leading to weaker stems, fewer leaves, and a significant lack of blossoms.
The relationship between the light we receive and our flowering is direct and non-negotiable. Ample sunlight acts as the primary signal and energy source for our reproductive cycle. It prompts the development of our flower buds and provides the metabolic energy required to produce and sustain our vibrant blooms. When we bask in sufficient sun, we can flower prolifically from spring until the first frost. Inadequate light disrupts this entire process. We become "leggy," stretching our stems thin and weak in a desperate search for more photons. This desperate growth comes at the expense of bud formation, resulting in sparse flowering or none at all, as we must divert all our limited energy to mere survival.
While we are sun-worshippers by nature, we are also remarkably adaptable. In regions with exceptionally hot, intense afternoon sun—particularly in peak summer—we can experience a form of physiological stress. The extreme heat and light intensity can sometimes lead to scorching on our leaves or cause our blooms to fade more quickly. In these specific climates, we appreciate a slight reprieve. A location that offers us glorious morning sun and then dappled shade or light afternoon shade is perfect. This pattern provides us with the high-energy light we need for the majority of the day while protecting us from the most punishing rays, allowing us to conserve water and maintain our lush appearance.
Life in deep shade is a constant struggle for us. Deprived of sufficient sunlight, our very structure changes. We become etiolated: our internodes (the spaces between leaves on the stem) elongate dramatically, creating spindly, weak growth that cannot support the weight of flowers or even its own leaves. Our foliage loses its rich, green hue, often becoming pale and yellowish as chlorophyll production declines. Our overall growth is stunted, and our immune system weakens, making us far more susceptible to pests like whiteflies and diseases such as botrytis. Essentially, we are existing, not thriving, in a state of slow decline.
When brought indoors to overwinter or kept as houseplants, our light requirements become even more critical. A south-facing windowsill is our absolute preferred location, as it typically provides the most intense and prolonged direct light available inside. An east or west-facing window can be adequate, but you must monitor us closely for signs of light starvation. Without the full spectrum and intensity of outdoor sun, we may still become leggy. In such cases, providing us with supplemental artificial grow lights for 12-16 hours a day can perfectly mimic our ideal outdoor conditions and keep us healthy and compact until we can return to the garden.
