Q10 – How do I position the Plant Booster device under a potted plant correctly?

Besides the basic use of the Plant Booster system for hanging baskets, using it for planters or potted plants is a really interesting way.  Whether it is for a pot full of flowering plants for growing vegetables, once you understand the principles of setting it up it will expand your world of possibilities with the Plant Booster system.

The Plant Booster device is essentially a spring loaded pinch valve.  Load, whether applied as a weight in tension (like for a hanging basket), or resting on the device (like for a potted plant) will cause it to deflect which will cause it to pinch the tube.  The control spring and wingnut are used to counter act this pinching.  The higher the load, the more the control spring must be compressed (by turning the wingnut clockwise) to try to keep the tube from closing.  At some weight, the tube does become pinched, and water stops flowing into the plant.  A slight reduction in the load, or weight, will cause the tube to be un-pinched slightly, thus allowing water through it to re-establish the weight again.

When the Plant Booster device is used to control water flow to a potted plant it is important to understand how the weight of the pot is  distributed.

There are so many different pot sizes and shapes, that each one will require a slightly different setup.  The way to do the setup is explained below.

In the picture above, which represents the most basic setup, the pot is resting on a block of wood, or fulcrum, (which goes right the way to the other side) and the device.   The pot is therefor resting on a straight pivot edge, as well as a device, which effectively makes it a very stable setup.   The weight of the pot is divided between the fulcrum and the device as indicated in the sketch below.

An upgrade from this setup is to make a base plate onto which the fulcrum block and plant booster device are screwed down.  This is more work, but will make the whole setup more reliable and make it easier to keep the pot in the right place on the plant booster device.  If someone cleans around the pot, with the most basic setup, the pot could be bumped and thus upset the balance, but if the device and fulcrum are screwed down to a base plate, the position of the pot on the setup is easier to correct if someone does inadvertently move the pot.

The principles of how to get the position of the pot on the fulcrum and the plant booster device are illustrated in the sketches below.

 When the fulcrum of moved closer and closer to the center of the pot, more and more of the weight of the pot will be transferred onto the fulcrum, and therefor less and less onto the device.  In the extreme, the full weight of the pot could be balanced on the fulcrum, and none on the device.   The trick is to find the position of the fulcrum for your pot where the weight transferred onto the device is within the capacity of the device.

An additional variable in this challenge is that the rim of the pot resting on the device can be moved closer or further away from the pivot point of the device.   There are markings on the top surface to aid with this.  The closer the rim is to the pivot point, the heavier the pot can be.  For light pots the rim should be further away from the pivot point.

In the experiment below it was possible, by moving the fulcrum to 5 cm from the center of the pot, to fill the pot to 207 lbs with water, and just remain within the maximum control range of the device.  In other words at this point if I touched the pot slightly to simulate it becoming lighter on the device, the device would still allow more water through.

My experiment was performed with a water pressure of 110 PSI (typical pressure at a garden tap supplied with city water).  At lower pressures results may vary slightly.

Therefor, by adjusting BOTH the position of the fulcrum relative to the center of the pot, as well as the rim of the pot resting on the device, the right positions can be determined for balancing your pot on a fulcrum and a device while staying within the control range of the device.

Once you have achieved a good setup, mark the location of the fulcrum and the rim on the device, so the setup can be corrected without much effort if the pot is moved form its position (such as when the floor is cleaned around it).

With a little practice, perhaps, like I did, with a container filled with water (so the weight is accurately known), you will soon understand how to set up the Plant Booster system on your pots.