CA1319257C - Potliner - Google Patents

Abstract

ABSTRACT

A unique disposable and collapsible nursery container for trees and shrubs is comprised of an outer plastic film bag and an inner bendable sheet of expanded polystyrene. The invention overcomes numerous problems which currently exist in the marketplace. In particular, the expanded polystyrene sheet is coated on the inside with a root pruning compound which prevents excessive root ball formation. In addition, expanded polystyrene has insulating qualities which protect the roots from excessive cold or excessive heating caused by exposure to sunlight. The present invention can be shipped and handled in a collapsed state thereby creating savings in storage and transportation.

Description

This invention relates to plant containers and more particularly relates to nursery containers for the propagation, transplanting and transportation of trees and shrubs.
Over the years, numerous containers have been proposed and used for the nursery industry. Because of a large scale operation, attempts have been made to lower the cost of containers used for trees and shrubs and to produce containers which take up a minimum of storage and shipping space.
At one time burlap sacs were used to contain and transport the root ball and growing medium of trees and shrubs.
Burlap has a number of problems associated with it. In particular, it does not retain sufficient moisture or is prone to rot in high moisture conditions.
More recently, attempts have been made to construct containers from papier-mâché or cellulose, wood fibres or a combination of the two. These containers are of a rigid construction and must be stacked for storage and shipping purposes. One of the drawbacks is that the containers tend to break down under high moisture conditions and the roots of the trees and shrubs planted therein tend to break through the pots.
Attempts to avoid the pot breakdown have been made by incorporating a root inhibitor into the paper mash mixture during construction, such as U.S. patent 2,848,842 (J.L. Tennant).
These containers have not been found to be satisfactory and still have the disaclvantage of requiring excess space during storage and transportation.

Thereafter, the industry changed to rigid molded plastic pots. These pots eliminated the problem of root penetration and destruction of the po~ itself, but the problems of excess storage space and high cost of manufacture still remained.
The newest development in nur ery containers is the change from rigid plastic pot~ to heavy gauge plastic film such as polyethylene bags. These bags are is easy to store and can be destroyed after use, and are inexpensive to produce.
~owever, both the rigid plastic pots and the plastic film bags have two serious drawbacks. Firstly, the treeR and shrubs tend to form an entwined root ball which is disadvantageous particularly for good growth after the tree or shrub is planted.
Secondly, there is damage done to the roots of the tree or shrub because of excessive heat or excessive cold. Because the trees or shrubs are kept above ground in the tree nursery in their containers, the temperature of the soil in the container varies a great deal more than that of the soil surrounding a tree planted in the ground. At night, as the temperature drops in the surrounding air, the soil surrounding the roots alRo undergoes a sudden lower temperature. Similarly, during the days the hot sun penetrates the black plastic bag or rigid pot and causes the temperature of the soil to rise dramatically. These fluctuations in temperature can severely harm the roots of a tree or shrub.

A si~ilar problem was encountered many years ago when metal containers were used for nursery trees and shrubs. This problem was partially solved by using an insulating cylinder within the wall of the container such as that disclosed in U.S.
patent 3,158,957 to W.T. Sierke.
It is therefore an object of the present invention to produce an inexpensive planting container for nursery use which has insulating qualities to moderate the temperature of the soil surrounding the roots.
It is a further object of the present invention to provide a container in which a tree or shrub can develop a suitable root ball which is not entwined or pot-bound. It is a further object of the present invention to provide a nursery container which is collapsible and disposable taking up little space during storage or shipping.
The present invention attempts to accomplish these objects by employing an outer bag made of strong plastic film and with an inner adjustable and bendable sheet of expanded poly~tyrene which forms a cylinder within the bag. The inner wall of the expanded polystyrene cylinder is coated with a root pruning compound.
Therefore, this invention seeks to provide a collapsible nursery container used for growing, transplanting and transporting trees and shrubs comprising:

an inner bendable sheet of expanded polystyrene, said sheet being coated on at least one face thereof with a root pruning compound, and an outer container means wherein in operation said sheet is inserted in said container and bent to form a cylinder capable of withholding a plant growing medium.
In a preferred embodiment of the invention a black plastic bag of at least 4 thousandths of a inch thickness, having a seam at the bottom with at least a twelve inch diameter provides an excellent outer container. Drainage holes are located in the bottom of the bag. Thereafter a sheet of expanded polystyrene of a uitable thickness such as 1/8 to 1/2 inch and preferably 1/4 inch which is coated on at least one face with a root pruning chemical is bent upon itself to form a cylinder and then inserted into the bag. This keeps the shape of the polyethylene bag.
A standard size sheet of bendable expanded polystyrene can be used and overlapped upon itself thereby making it functional for bags of different diameters. For example, by increasing the overlap the same sheet can be used in a smaller sized bag.
Once the sheet has been formed in a cylinder and overlapped and attached to itself by a suitable attachment such as a staple or clip, the growing medium is introduced into the bag along with the tree or shrub which is to be transplated or transported. The expanded polystyrene sheet mo~erates the temperature of the growth medium and thereby avoids excessive heating or cooling of the roots. The root pruning compound arrests the growth of the roots once they reach the sides of the pot and thereby avoids excessive root ball formation and sprialling. The drainage holes in the bottom of the bag provide sufficient drainage in order to avoid rot due to excessive moisture.
In another embodiment of the invention, the liner i.e.
the sheet of expanded polystyrene with a coating, can be used inside a standard black plastic rigid nursery pot to provide the same root pruning and insulating qualities.
In operation, the plastic film bag is opened and a sheet of expanded polystyrene is bent to form a cylinder which is inserted in the bag. The tree or shrub and growth medium is added and the container placed on the nursery storage site. In order to transplant the tree or shrub, the plastic outer sac is simply cut with a knife and the cylinder removed by removing the attachment means, or cutting it with a knife if the insulating sheet is not to be recycled. The tree or shrub has roots in a good formation, which can be easily placed in a new area in the soil with no disturbance to the roots.
The invention is more fully described in conjunction with the following drawings wherein:
Figure 1 is a perspective view of the nursery container;

Figure 2 is a cut-away view of line A shown in Figure l, and Figure 3 is a top view of the container.
In Figure l we note there is a plastic film bag l in which is inserted in a cylindrical form a bendable sheet of expanded polystsyrene 2. The inside of the cylinder 2 is covered with a ~uitable root pruning compound 3 such as cupric carbonate.
In Figure 2 one can see that the bendable sheet of expanded polystyrene overlaps itself to form the cylinder at 4.
In this manner the bendable sheet of expanded polystyrene can be overlapped upon itslef to any degree in order to fit bags of various diameters. The overlapping portion of the expanded polystyrene 4 is fastened to itself by a clip means 5.
Figure 3 is a top view of the container of the present invention. One sees the outer plastic film bag l surrounding the bendable sheet of expanded polystyrene 2 and the base of the bag 6 which is comprised of a number of folds 7 which terminate in a seam 9. The base of the bag has a number of apertures or perforation~ 8 which act as drainage holes.
In another embodiment of the invention, the bendable sheet of expanded polystyrene can be placed in a Ytandard rigid plastic nursery pot and provides the same insulating and root pruning qualities.

Claims (5)

1. A collapsible insulated nursery container used for growing, transplanting and transporting trees and shrubs comprising:
an inner bendable sheet of expanded polystyrene, said sheet being coated on at least one face thereof with a root pruning compound; and an outer container means comprising a bag formed from plastic film of at least 4 thousandths of an inch in thickness wherein in operation, said sheet is inserted in said outer container means and bent to form a cylinder, such that said container is capable of holding a plant growing medium.

2. A container as claimed in claim 1 wherein said expanded polystyrene sheet is overlapped upon itself thereby permitting the formation of a complete cylinder in bags of varying diameter.

3. A container as claimed in claim 1 wherein said bag is perforated for drainage purposes.

4. A container as claimed in claim 1 wherein said sheet of expanded polystyrene has a thickness of 1/8 to 1/2 inch.

5. A container a claimed in claim 1 wherein said root pruning compound has a copper base.