Patience, please! From my perspective, I am a vigorous but sometimes slow-to-mature vine. If you planted me from a small nursery pot this season or started me from seed, my entire biological focus is on establishing a strong root system and growing healthy leaves and stems. Blooming is an energy-intensive process, and I simply may not be ready. Many of my kind, especially the popular Passiflora incarnata (Maypop) and Passiflora caerulea, need a full growing season or two to become established before they divert precious resources to flower production. My priority is survival first, reproduction later.
This is the most common reason I withhold my blooms. I am a sun-worshipper at heart. To produce my intricate flowers, I require a tremendous amount of energy, which I get directly from the sun through photosynthesis. "Full sun" means I need at least six to eight hours of direct, unfiltered sunlight each day. If I am planted in a shady spot or am shaded by larger trees or structures for most of the day, I will focus my energy on growing vines and leaves to try and reach the light. Without sufficient sun, I simply cannot muster the energy required to create buds and sustain flowers.
Your intentions are good, but that high-nitrogen fertilizer you are using is telling my body to do one thing: grow leaves! Nitrogen promotes vigorous green vegetative growth. While this makes me look lush and healthy, it comes at the expense of flowers. To encourage blooming, I need a fertilizer that is higher in phosphorus (the middle number in the N-P-K ratio). Phosphorus is the nutrient that specifically supports the development of roots, flowers, and fruits. A fertilizer labeled "Bloom Booster" or something similar with a ratio like 5-10-5 would send me the correct signal to start the flowering process.
I am a notoriously fast and large grower. If I am living in a container that is too small, my roots quickly become pot-bound. When there is no more room for my roots to expand, I become stressed. This stress signals that my environment cannot support offspring (seeds within fruit), so I see no point in blooming. Similarly, if I am in the ground but competing with the roots of other plants, trees, or shrubs for water and nutrients, the same stress response can occur. Ensuring I have adequate space for my root system is crucial for flower production.
I produce my flowers on new growth. If you pruned me aggressively very early in the spring, you may have removed the budding points from which those new, flower-bearing vines would have emerged. A light pruning to shape me or remove dead material is fine, but a heavy-handed cut too late in the season can significantly reduce or delay flowering. The best time for major pruning is in late winter or very early spring, just before new growth begins, so I have the entire season to regenerate and produce flowering wood.
I thrive in consistently warm conditions. A late spring frost can damage my tender new growth, including nascent flower buds. An unusually cool, cloudy summer provides less solar energy for photosynthesis. Even a period of extreme heat coupled with drought can cause me to drop buds to conserve water and energy. My blooming is heavily influenced by environmental factors beyond your control. A sudden shift from cool to hot weather can also shock me, temporarily halting bud development.
