Put two of these vines side by side and the answer to the cypress vine sun requirements question shows itself fast. The one in a sunny spot covers itself in scarlet, star-shaped flowers from top to bottom. The one tucked against a shaded fence grows tall and leafy, but you have to hunt for the few blooms hiding in all that green.
So cypress vine likes sun, plain and simple. A cypress vine full sun spot gives you the best flowering, and the plant only tolerates a little light shade beyond that. The lush leaves in shade can fool you into thinking the plant is happy. But a vine grown for those bright red trumpets needs strong light to deliver them, and weak light always shows up as weak bloom.
The reason behind this comes down to energy. Flowers cost the plant a lot to produce, and that energy comes from sunlight hitting the leaves all day. More direct sun means more fuel for more blooms. Move the same vine into shade and it still grows, sometimes faster and leafier, because it stretches to reach light. But fewer flowers form, so you trade those scarlet stars for a plain wall of foliage. The plant chooses leaf growth over flowers when light runs short, and you end up with a cover crop instead of a flowering vine.
That tradeoff catches a lot of gardeners off guard. A vine in part shade can look healthy and grow fast, so it seems like the spot works fine. Then summer arrives and the blooms never show up the way you hoped. The plant is doing exactly what shade tells it to do. It puts its energy into chasing light rather than into the flowers you planted it for in the first place.
Two extension offices back this up. MSU Extension says full sun is best for flowering and notes the vine tolerates a little light shade. University of Illinois Extension lists its range as full sun to partial shade. Both point the same way. The vine survives in part shade, but the show you actually want comes from sun.
Knowing the cypress vine light needs makes siting the plant easy. Pick a place that gets at least six hours of direct sun a day, and more is better. A south or west-facing fence, trellis, or arbor works well, since those spots soak up the most light from morning through afternoon. Skip the north side of the house. Skip any spot that a tree, wall, or taller plant shades for most of the day. That shade cuts your flower count before the vine even gets going.
Hot southern gardens get one small break here. In regions where summer afternoons turn brutal, a bit of light afternoon shade is fine and won't cost you many blooms. The vine still drinks in plenty of morning and midday sun, which does most of the work. A touch of relief from the harshest late-day hours can keep the foliage from scorching and the soil from drying out too fast. Just don't mistake that small allowance for an excuse to plant it in deep shade.
Light and water also work together for this vine. A plant in full sun dries out faster, so a sunny spot usually means you water more often during the hottest stretch of summer. That is a fair trade for the bloom you get back. Keep the soil from going bone dry and the vine rewards the sun with a steady run of flowers that pull in hummingbirds from midsummer right up to the first frost.
Bottom line: give cypress vine the sunniest spot you have. Six hours or more of direct light keeps it loaded with flowers, hummingbirds keep showing up, and the vine pays you back all season long. Shade it heavily and you get a green curtain with hardly a red star in sight.
Read the full article: Cypress Vine: Care, Flowers, and Facts
