An electronic leaf is a device that controls when and how often cuttings receive mist. There are several different varieties available and all of them work in the same basic way. As mist falls on the cuttings it also falls on a mechanical leaf that is attached to an arm that pivots. Moisture accumulates on the leaf and the weight of it pushes the arm down. When the arm is all the way down, a switch is triggered that interrupts the electrical signal that operates the misting solenoid.
The moisture will evaporate off the electronic leaf at a rate that simulates the actual evaporation from the cutting’s leaves and as this happens the electronic leaf arm will slowly pivot upward again. When the arm pivots high enough the electrical signal will once again pass through to the solenoid and mist starts falling on the cuttings again. This process repeats itself and because the moisture on the electronic leaf is mimicking what is happening on the cutting’s leaves, the cuttings receive the proper amount of moisture.
One of the best reasons for using an electronic leaf is that it mimics the actual evaporation rate of moisture from the cuttings which means they only get the amount of moisture they need. If your misting beds are located outside and not under a poly house or in a greenhouse, the moisture in the environment changes frequently. If it rains or even drizzles the electronic leaf compensates for the changing levels of moisture automatically.
An electronic leaf also gives the cuttings as the water they require which helps eliminate over misting and saves water. Over misting can cause plant stems to rot, increase the spread of fungi and diseases and encourage leaching of nutrients in the cuttings. Using just enough mist to keep the cuttings moist helps reduce the likelihood of any of these things happening.
Electronic leaves also have a few drawbacks. The mechanical leaf can be affected by bugs, slugs, birds and other creepy, crawly things. This happens more frequently if the cuttings are outside and not in a greenhouse, but it can also happen in a greenhouse. If anything like a bug, slug, or bird dropping lands on the electronic leaf, the arm can pivot downward and shut off the misting cycle until the bug or slug decides to move away. If the bug or slug decides to stay on the leaf for a while, the cuttings will not receive any moisture when they should and the crop could be damaged or even lost. Bird droppings are worse because they stay on the leaf until it is cleaned. And just like with a slow moving bug, if this problem isn’t resolved in a timely manner, the crop could be jeopardized.
Salts and minerals can also accumulate on the mechanical leaf itself. Over time they begin to add weight to the arm which affects calibration and accuracy. Using hard water requires frequent cleaning to remove the deposits and can become very time consuming.
Electronic leaves can be quite useful for plant propagation, but research them and make sure you understand the environment they will be used in before making a purchase. The initial cost of the leaf can outweigh the benefits if it requires frequent service or an entire crop is damaged or lost.