Plant Hardiness

• Split-leaf philodendron is among the most cold hardy of all tropical philodendrons, according to the late Robert Riffle, author of "The Tropical Look." If frost never occurs in your region, planting split-leaf philodendron outdoors is completely safe. Typically, horticulturists consider the plant hardy outdoors in U.S. Department of Agriculture plant hardiness zones 9b and warmer. However, in USDA zone 9a, occasional, brief bouts in the 20 to 25 F range kill extant leaves, but new foliage emerges in mid-spring from the growing tip on the trunk. If the tip freezes, regrowth won't occur.
  
  

Light Needs

• The best light conditions for a split-leaf philodendron are dappled partial shade, such as that experienced under tall trees. In extremely low-light levels, fewer but larger leaves grow and the plant's growth rate slows. Conversely, too much intense, hot sun rays scalds leaves and increases plant water needs. Site the philodendron where it receives no more than four hours of direct sunlight daily. An eastern side of a building works well since the plant becomes shaded by midday.
  
  

Soil

• Regardless of light conditions, for the split-leaf philodendron to produce large, robust and deep green leaves it must grow in a fertile soil. A sandy or loam soil rich in organic matter proves the best soil. An evenly moist, but well-drained ground supports lush growth too. Soils should become slightly drier during the cooler winter months. Avoid high pH (alkaline), dry sand, compacted clay or soggy, mucky soil types. In cooler, shady garden spots, the need for soil moisture diminishes somewhat. If exposed to more sunlight, drying winds or in sandy soil, the need for constant soil moisture helps prevent leaf scalding or premature yellowing or dying.
  
  

Size Considerations

• Resist the urge to plant a split-leaf philodendron too closely to a building foundation or cramped next to other tropical plants. Plant it so at least 3 feet of open space exists all around it. Often nurseries sell containerized plants that are easy to handle and look compact and tidy. Once growing outdoors, the leaves enlarge as the roots establish. Each leaf stem petiole grows 3-feet long. Therefore, a small plant quickly becomes 5- to 6-feet wide as new leaves radiate from the growing tip. This species is also called the tree philodendron; over several years the trunk grows upright or leans to the light and looks like a small palm.