Philodendron Congo and Rojo Congo

Philodendron ‘Congo’ PAT#11724 and ‘Rojo Congo’ PAT#14116 are medium to large, self-heading Philodendrons with very thick, glossy leaves suitable for interior use in 6” to 10” containers. ‘Congo’ is green. The new foliage of ‘Rojo Congo’ opens red and matures to a dark green with a red blush. The leaf petioles remain bright red.

Handling liners: Young plants are supplied as 98 cell pack liners. Liners of the Congos should be potted as soon as possible after delivery. Plant them deep so that the base of the plant is covered with soil. This will ensure that the finished plant will not ‘wobble’. First plant into 4” or 6” pots. After a full root-ball has developed, pot into larger pots. For fullness, use 2 to 3 plants for a finished 10” container.

Soil: The Congos require a light, well-drained soil and good aeration. Use mixes such as 50% Canadian peat, 30% bark, and 20% perlite; or 60% Canadian peat, 25% bark, and 15% perlite. The pH should be between 5.5 and 6.0. In order to keep the pH at this level, use a modest amount (2-3#) of dolomite per cubic yard (depending on the pH of the peat). Incorporate 1 to 2# gypsum for additional calcium. If the pH creeps above 6.0, top dress with granular sulfur (15 grams per 10” pot should suffice), or drench with iron sulfate. Canadian peat is helpful in maintaining a low ph.

Fertilizer: The Congos are fairly heavy feeders. Incorporate a slow release fertilizer such as 15-9-12 with 1 lb./cubic yard of magnesium sulfate into the soil before planting. ‘Congo’ is a fast growing philodendron, so when roots are well developed (about 6-8 weeks after planting) the plants can be fertilized with a liquid fertilizer such as 24-8-16 or 20-10-20 at a rate of 150 to 200 ppm N (EC~1-1.5) maintaining soil EC~1.0. As plants mature, apply additional Magnesium weekly.

Water: Over-watering will induce root rot in Philodendrons. While the young plants establish new roots, keep the soil evenly moist but do not over water. After the roots have penetrated beyond the liner root ball, monitor moisture levels carefully.

Light: In order to maintain good foliage color and growth, light levels should be kept between 1500 to 2500 f.c. (73%-80% saran). Higher light may cause yellowing and susceptibility to diseases.

Temperature: The optimum day temperature for the Congos is 76 to 86º F, with soil temperature no less than 65º. Although the plants will tolerate temperatures as high as 104º for brief periods, higher temperatures will reduce growth rate and increase disease susceptibility. Maintain night temperatures between 65 and 72ºF. Again, lower temperatures are tolerated, but will slow growth. Damage can occur at 40ºF.

Pests: Thrips, aphids, spider mites, and scale. The Congos can host Tumid mites (red mites) which may cause small necrotic spots (see enclosure). Significant crop damage can occur with only a few Tumid mites, so preventive applications are important (rotate Vendex, Avid (6 oz. rate), and Kelthane).

Diseases: Root rots such as Phytophthora and Pythium are a problem only if the soil is too heavy or too wet. Under dry conditions, the plant is fairly resistant to Erwinia. Extremely hot, wet conditions are conducive to infections of Erwinia. When these conditions prevail, a preventive program of copper-based bactericides is suggested.

Other: These plants are fairly vigorous growers. From a liner to 6” pot takes 16 to 18 weeks of growth. Three plants in a 10” pot should finish in 7 to 8 months. Plants should have a fully developed rootball before shipping and going into the interior.

This text is a recommendation only; it is not an endorsement of any products or acceptance of any liability as a result of usage.