Container System facilitates air pruning of tree roots.

Press Release Summary:

Suited for tree seedling production, RigiPot(TM) 25-350 system consists of white trays with solid walls on outside edge for placement on perimeter of growing compound, and black trays with slits on all cell walls for interior placement. Solid walls protect roots from wind and other harmful elements, while slits allow for ventilation and enable air pruning. Reusable trays have 25 cells of 350 cc volume, tapered cavities, inner ribs that minimize root spiraling, and drainage holes.

Original Press Release:

IPL Reusable RigiPot(TM) 25-350 Enables Air Pruning to Strengthen Roots Without Over Exposure to Elements

When nurseries have a need for specialized growing containers, Stuewe & Sons often turns to IPL Products Ltd. Stuewe & Sons, Inc. offers a complete line of nursery containers, including IPL RigiPots(TM), for tree seedling production. The RigiPots are sturdy, reusable, one-piece seedling trays designed to yield a high number of seedlings per square foot. IPL has been supplying the containers for the nursery and forestry industries for about three decades.

Recently, a long-time customer of Stuewe & Sons approached the company looking for a container with special features that would accommodate Douglas Fir seedlings grown for reforestation.

"We've always had excellent service from IPL and have found the company to be open to innovation so we contacted them with our customer's design request," said Eric Stuewe, president and co-owner of Stuewe & Sons.

The design challenge was to create a container system that would not dry out the root system but still enable air pruning. IPL began with an existing RigiPot tray that has side slits on each of the 25 cavities within the tray. These side slits enable air pruning which strengthens the root system. "The root pruning affect is the same each growing season, producing a consistent crop each year."

IPL modified its existing container system so that it now includes trays with solid walls for cells on one outside edge only. The new tray is white to differentiate it from the black containers with slits on all vertical cell walls.

The IPL trays are placed side by side in a large "growing compound". The white trays, with solid walls on the outside edge, are placed on the perimeter of the growing compound. The black trays with slits on all the cell walls are placed in the interior of the growing compound.

"The outside edge of the growing compound is exposed to wind and other elements that can dry out the root system," explained Stuewe. "However, the inner cavities need the slits for ventilation, so only a small percentage of the trays need solid walls. IPL addressed both issues with its new system, the RigiPot 25-350.

"IPL was very willing to make this creative adjustment to their product and they gave us excellent pricing. The design features and price won our customer over to the IPL RigiPot 25-350," continued Stuewe.

Since using the IPL RigiPot, the customer has found that the cavities provide the largest volume and highest growing density of any container it has used. Also, the square shape of the cavity makes efficient use of space.

Because the slits in the containers allow the plug to drain thoroughly, the grower can easily maintain the moisture level by either adding or holding back watering. Even during heavy rain periods, the slits adequately drain the water from the plug.

Other features of the IPL RigiPot that are attractive to nurseries include:
o 25 cavities (cells) of 350 cc volume each.
o durability that allows for years of reuse;
o ease of extraction of seedlings from the container;
o lack of root penetration;
o ease of cleaning;
o lightweight for ease of handling in the greenhouse and field;
o tapered cavities that reduce plug removal effort and root shock;
o inner ribs that minimize root spiraling, and
o lateral drainage holes that eliminate over watering.

"The service from IPL on this and other products has been excellent. IPL gave us good pricing which we passed on to our customer. And they even delivered the product early. The innovation of IPL helps Stuewe & Sons provide the most productive growing systems and supplies available anywhere in the world," said Stuewe.

About IPL
IPL is a North American injection molding and extrusion product leader. It was the first injection molder in North America to earn ISO 9001 quality certification. It achieved QS 9000 certification in 1998. The company's headquarters are in St. Damien, Quebec. Total sales in fiscal year 2003 - 2004 were $209 million (CND) servicing the material handling, custom molding, packaging, and environmental markets. For more information, visit the company's Web site at

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