The plastic tent method, also called kulob method, is the technique of enclosing potted planting materials with a plastic bag. The method is commonly practiced in plant propagation by stem cuttings.
But it has another important application, one which can be considered as both cost saving and life saving. Cost saving in the sense that the technique eliminates the need to hire labor or to pay services. Life saving too, that is, for your favorite plant.
Maybe you have a scheduled trip away from home for several days? A business meeting, or a seminar, or a vacation with the whole family?
And you are worried that you have nobody to attend to your favorite potted plant?
Indeed such is a well founded concern. Potted plants need regular watering and having nobody to do it is rightfully a cause for concern.
It should be more real with bonsai. Having a little amount of soil to hold water, the tree is susceptible of injury within just a few days due to dessication.
Yes, you can proceed with the trip and stop worrying that there’s nobody to do the watering of your precious plant. Or consider that at least there’s a fighting chance that your plant will still be alive when you come back.
All you need - the most essential - is one plastic bag that is big enough to accommodate the plant and its pot. Preferably it should be transparent, but other colors will do as well. We have in fact used blue, green, yellow and red plastic bags in propagating bare-root wildlings and bonsai materials for years.
You can do it just before or a day or a couple of days before leaving. Here’s a basic step-by-step guide in installing a plastic tent for outdoor plants under tropical setting:
1. Find a spot outside that is under partial shade and well ventilated. It may be under a tree with thick foliage or an improvised shed can be made. Also prepare the following materials to use: 1 plastic bag, 4 stakes, and 4 rocks.
The plastic bag should be wider than the canopy of the plant and longer than the vertical distance from the base of the pot to the tip of the plant. The stakes are of about the same length as the plastic bag. The rocks are to be used as weights.
2. Slightly elevate and level the spot on the ground where the potted plant is to be placed.
3. Drench the spot and the immediate surrounding with water.
4. Place the pot on the levelled ground.
5. Sink the four stakes on the ground in square or rectangular arrangement around the plant.
6. Pour sufficient water to saturate the potting soil. Also sprinkle water on the leaves.
7. Insert the plastic bag downward with the bottom up, using the stakes as peripheral guide.
8. Ensure that the edges of the plastic bag remain pressed on the ground by weighing with rocks.
Note: The attached images demonstrate further the procedures.
The plastic tent set-up should provide the following optimal conditions for continuing plant growth:
1. Prolonged supply of water. Water from the ground and the potting medium will be recycled over extended period because the plastic bag will prevent its escape into the atmosphere. Liquid water will be converted to gaseous water in the processes of evaporation and transpiration and back again to liquid water through the process of condensation.
The set-up may also be benefited if there is rain. Water inside will be replenished by runoff and seepage.
2. Available light. Light will be available at low intensity because the plastic tent is under partial shade (or partial sun). A film of water adhering to the inside of the plastic bag also makes the plastic hazy. This condition will prevent injury to the plant due to excessive heat.
3. High relative humidity. The plastic tent enclosure will ensure high humidity inside. Consequently evaporation from the ground and potting medium as well as plant transpiration rate will be reduced. This will further conserve water within the enclosure.
4. Warm temperature. It will be warm inside the plastic tent because the plant will continue to release body heat and heat from the sun will pass trough the plastic bag. Much heat will be trapped in water inside. But wind and rainfall will have refreshing effect.
5. Continuing supply of carbon dioxide and oxygen. The plant will continue to photosynthesize and respire with CO2 and O2 being recycled.
6. Sufficient space for growth and avoidance of heat injury. The use of a relatively big plastic bag in the set-up will ensure that there is sufficient space for sideward and upward growth extension. Further, scalding effect of severe light will be prevented because the leaves of the plant do not touch the plastic bag.
The above procedure should mainly serve as a basic guide.
Many modifications can be made. For example, the stakes can be slanted so that the tips are bunched on top of the plant. The resulting plastic tent will be pyramidal in shape.
It is also possible to insert the pot into the plastic bag with its opening on top. The edges on top are then gathered and tied together.
Depending on size of pot and plant, other materials instead of plastic bag may likewise be used as enclosure. A qlass aquarium with moist bed of sand or soil may be placed anywhere even inside the house or somewhere with a roof provided that there is light exposure. To seal, a plastic sheet is spread on top and the edges are fastened around the aquarium with a tape or tying material.
We have no documentation on the number of days that any plant should be allowed to remain inside a plastic tent. It is possible that the duration will depend on various factors such as plant adaptation, whether or not the plant is completely confined inside, the amount of light reaching the plant, and the occurence of rains.
Nevertheless, we have determined that molave bonsai on training can endure being inside a plastic tent for two months. Some plants that we raised in terrarium or bottle gardens also remained alive even after a year.
- Ben G. Bareja July 23, 2019