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Planting Hole Placement
PHP Technology

PHP technology consists of polymer-coated fertilizer that enables the controlled release of nutrients over an extended period of time, conveniently packaged in a biodegradable transplant pack. When this pack is properly placed with the roots at transplant, it'll provide nutrients to developing tree seedlings as they begin to get established and increase their nutritional demand. 

How do the new PHP products work?

The nutrients within the teabag are coated with a high-performance polymer coating that precisely controls the speed of nutrient release over a set period of time.

As a result of that high degree of control, foresters can safely place the teabags in the same hole as the seedling without fear of killing it.


Just like our coatings in the past, our new PHP products break the feast or famine cycle associated with conventional and inferior slow-release technologies. This ensures that the nutrients remain available to the seedling and are not leached into the environment.


Semipermeable Membrane

As soil temperatures rise, osmotic pressure induces the movement of water molecules from low concentration to high concentration, moving water into the prill. 

As pressure rises inside the prill, water molecules transport nutrients out of the cell, into the soil via reverse osmosis.

The polymer coating on the surface of the prill has pores that create a semi-permeable membrane, allowing water molecules to pass through. 

Water Enters Prill

Water Carries Nutrients Out

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How Does the Polymer Coating Work?

The polymer coating is activated by moisture and the speed of release is affected by soil temperatures. As the soil temperatures rise, osmatic pressure builds within the polymer coating, opening channels and releasing the fertilizer into the soil through reverse osmosis. The warmer the temperature, the greater the osmotic pressure that develops within the coating, creating a quicker release. As the soil temperatures cool, the osmotic pressure decreases and the release of nutrients through the polymer coating slows down.

In fact, if temperatures are too cold for roots to grow, the membrane will close, holding the nutrients in place until conditions are again favorable.

Also of note, is that the rate of nutrient release by the polymer is not significantly affected by soil moisture, soil type, soil pH or microbial activity. For instance, if soil temperatures are consistent, the rate of release will essentially be the same whether soils are saturated or they have minimal moisture levels for plants to grow. If soils are entirely dry (i.e. plants will wilt because they can no longer access moisture) the nutrients will stay put until moisture becomes available again.

Does placing fertilizer in the same hole kills trees?
How does RTI know PHP products will not damage trees?

Given we are in the business of helping you succeed, we would never recommend anything unless we were confident that it works. Since they were introduced in 2013, up until the end of the 2021 planting season, over 71 million RTI PHP teabags have been utilized on the BC Coast and throughout the BC Interior in a wide range number of different ecosystems with numerous species. When implemented according to our instructions, to date, RTI has not received any complaints of seedlings being burned or killed by any of our PHP teabags. We are confident that they will work for you!

What are the advantages to converting to the new PHP products?

SIMPLICITY — Tree planters will be happier with a simplified process, leading to greater efficiency at the time of planting, and greater planting quality. The less time they take to plant the trees, the lower the cost of labor. Therefore that extra time can now be allocated elsewhere, and the faster your trees get into the ground. And every day of cool, spring weather to establish counts!

MORE CONSISTENT PERFORMANCE — You will benefit a from the more consistent result as the teabag will always be placed in the right spot, close to the seedling. How many times have you gone out to the field to check the planters and couldn’t find the teabag? It may be because they put it too far away fearing that they would burn the tree with the fertilizer. Being able to place the teabag in the same hole ensures that you get the full benefit of the fertilizer you are paying for.

ENHANCED SAFETY — Product safety is always on our minds given the concern of tree planters handling teabag fertilizer. We want to do our best to address their concerns and to assure planters that what they are handling is safe. Not only are the levels of heavy metals lower in the fully coated fertilizer prills, well within safety guidelines for the PHP teabags, but the polymer coating also provides an additional layer of protection to prevent contact between the tree planter and the nutrient contents.

For more information regarding the RTI PHP advantage, please contact Darius Bucher, RPF, Integral Forest Management Ltd. At 250-318-8861 or by e-mail at
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