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Why We Use RPM
Vicky Bartish and Michelle Curran-Kimball
Root Pruning Method , or RPM , is a patented process developed by Forrest Keeling Nursery in Missouri. Trees and shrubs grown using this incredible technique develop superior root quality, which results in superior root mass. What this means to you is that they grow faster, more vigorous, and stronger specimens than those grown with average growing methods. High Ranch has been growing selected plants using this special technique for over three years, and is your exclusive grower of RPM plants for Northern California.
We invite you to come visit these incredible tree and shrub selections growing up to twice as fast as you normally expect. The key to these plants is their beautifully developed root system that is fibrous, full, and not root-bound! Since they are started in pots that prevent circling roots, the root system continues to grow outward, not around in circles. Consequently, our customers do not run into problems down the road with girdling roots and poorly developed root systems. This is a huge benefit to retailers and landscape contractors: your customers have less trouble planting these plants and the chances for failure are decreased. They establish themselves quickly with a healthier root system. There are fewer returns, higher success rates, and happy home gardeners.
We recently learned of some incredible benefits that trees grown with this method have contributed to the international effort to reforest degraded lands. Studies performed by Queens University in Northern Ireland show that the RPM method produces quantifiably better trees in a much faster time period than any other root-pruning system. This is an important breakthrough for the earth; the Kyoto agreement that was put in place to assure a sustainable environment for human life requires countries who sign to keep a certain percentage of their country’s landmass forested, or replenish it. The qualities of RPM -grown plants lend themselves perfectly to this cause.
In the US, projects in Missouri have shown that this special technique dramatically increases survival rates of trees in restoration projects, from the original 10% expected of bareroot seedlings to an amazing 90% survival rate for #5 RPM grown trees. Another great environmental benefit includes the use of mychorrhizae fungi in the planting process- living organisms that help plants take up and process nutrients in the soil much better- making it possible to use far less fertilizer, which in turn reduces run-off and the pollution of groundwater systems.
You will find our RPM selections in shorter but wider #5 and #15 cans in order to accommodate the wider root mass of the trees and shrubs. Tree choices grown in the “squat” # 5s include Acer species , Betula pendula, Cedrus deodara, Celtis sinensis , Grevillea robusta , Liriodendron tulipifera , Nyssa sylvatica, Pistacia chinensis, Platanus racemosa, Prunus cerasifera varieties, Quercus species, Sequoiadendron giganteum and Washingtonia robusta . Currently we are also growing Loropetalum , Coleonema, and Hydrangea quercifolia ‘Snow Queen’ in #3 pots using this amazing method and find them to be of outstanding quality as well. Be our guest and check the root balls! Keep a look out for a comparison planting we will be installing at the nursery to show you firsthand the remarkable strength, vigor and health of RPM plants.
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