JARS v64n1 - Tips for Beginners: The Magic of Shredded Pine Bark

Tips for Beginners: The Magic of Shredded Pine Bark
Mark Konrad
Sewickley, PA

Dr. Mark Konrad of Sewickley, Pennsylvania, submitted his choice for the "ideal" medium additive for propagation.

Sometimes I think the horticultural gods designed shredded pine bark especially for rhododendrons. Pine bark is valuable both for seedling culture and also as a medium additive for propagation. The combination of shredded pine bark and Canadian peat has proven ideal for container culture.

Shredded pine bark is an excellent medium additive for the following reasons:
1. Promotes an ideal pH. The low pH also suppresses unwanted microbial growth.
2. Allows for moisture retention with good aeration along with equal distribution of moisture in container culture.
3. Supplies an environment for mycorrhizal growth which is important in rhododendron culture.
4. One might speculate that the shredded pine bark produces organic acids, perhaps an important factor in the luxuriant growth of rhododendrons.

When adverse soil conditions are encountered (non acidic), pine bark and sand can be added to the soil and then placed in elevated beds for custom culture. Horticultural sulfur can also be added as needed to adjust the pH to a satisfactory acidic level.