Note: Descriptions are shown in the official language in which they were submitted.
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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.
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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.
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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:
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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
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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;
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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.
