Philodendron atabapoense | Atabapo Philodendron 4”

Long, narrow leaves with deep green upper surfaces and striking reddish-purple undersides give this species a dramatic look from almost every angle. Native to Amazonas, Venezuela, it grows naturally as a climber in wet tropical forest. Juvenile foliage can show particularly strong violet-purple coloration underneath, while mature plants develop much larger, elongated leaves that emphasize the contrast between the two surfaces.

This is a true climbing Philodendron rather than a self-heading plant. As the stem develops, aerial roots emerge from the nodes and can attach to trees or other vertical surfaces. Give it a moss pole, plank or other sturdy vertical support if you want to encourage its mature growth habit. With support and enough usable light, successive leaves can become substantially larger and more elongated. Mature leaf blades in the wild have been documented at approximately 20–25 inches long.

For natural light indoors, place it 1–3 feet from an east-facing window or 2–4 feet from a west-facing window. It prefers approximately 800–1,500 foot-candles at the leaves. Foot-candles simply tell you how much light is actually reaching your plant. The lower end can support growth, but stronger usable light within this range can help maintain tighter growth and support increasingly substantial foliage. If the spaces between leaves begin getting longer, successive leaves become smaller or the stem begins reaching strongly toward the window, move it closer to its light source.

Under a grow light, use a full-spectrum 5000–6500K fixture positioned approximately 8–12 inches above the canopy, aiming for 800–1,500 foot-candles at the leaves. Kelvin describes the color of the light, while foot-candles tell you how much light is actually reaching the plant. Keep the fixture positioned over the active growing point and move it upward as the plant climbs. A plant can continue growing under lower intensity while gradually producing smaller leaves and longer internodes, so the newest growth is an important part of evaluating whether the light is actually sufficient.

Water when your plant needs watered. Allow it to use a good portion of the available moisture before watering thoroughly again, but avoid repeatedly taking an actively growing plant to an extreme dry. Use a loose aroid mix with potting material for moisture retention combined with chunky bark and perlite or pumice to maintain air space around the roots. A climbing plant with a large root system and increasingly substantial foliage can begin using water much faster than it did when young, so adjust according to the plant and root zone rather than keeping the same watering pattern as it grows.

Watch the newest leaf, internode spacing and attachment to its support. Successive leaves becoming smaller while the stem continues growing can point toward insufficient usable light, lack of support or a change in root health. Increasingly long spaces between leaves are another useful light cue. New leaves can emerge softer and differently colored before hardening, so evaluate their final appearance rather than judging them immediately after unfurling. If new growth repeatedly emerges undersized or distorted, look at light, moisture consistency and the root system together rather than treating the leaf itself as the problem.

Success looks like a stem actively climbing its support, aerial roots beginning to attach, relatively compact spacing between nodes and successive leaves becoming increasingly substantial. As the plant matures, the long narrow foliage becomes the dominant feature, with the green upper surface and reddish-purple underside creating its characteristic contrast. The goal is not simply a longer vine. A climbing plant producing larger leaves as it moves upward is a much better indication that its environment is supporting mature growth.