Watering is an essential factor to plant health and longevity. There are two major practices in how one waters their plant: overhead or below the plants vegetation. Both of these practices have their place when growing plants, but which one is right for you and your growing environment?
If you are currently using sprinklers, misters or watering wands and your foliage is wet after you irrigate; then you are using the overhead watering practice. When watering turf grass and small plug trays or inserts, overhead watering is the only feasible method of irrigation. This practice is also great for increasing the humidity around the plant's leaf which lends itself to being used in propagating plants. The increased humidity reduces water lost through respiration which reduces stress to the cutting. This practice will also produce increased success in rooting. Watering overhead can help remove some insects as well as dust particles. Some plants also benefit from a foliar application of fertilizer that can be added to the overhead watering system.
The problem you might encounter with overhead watering is the increased risk of diseases. The higher the humidity and the longer the leaf is in contact with water; the more the conditions are right for diseases. To combat this problem you would have to spray fungicides more frequently such as Phyton 27. Another way to prevent diseases from overhead watering would be irrigating your plants in the morning. This gives the plants time to dry before the intense scorching sun of the afternoon and it also prevents water from remaining on the leaves during the night where less evaporation and higher relative humidity occurs. Hard water spots on the leaves could be an issue when irrigating overhead with hard water. To get rid of hard water residues you can spray on a leaf polish like Lustre-Glo. Another downside is that overhead watering does not direct the water to the planting media, and the surrounding surfaces could see more water than the plants roots. This excessive waste could cost you more financially in fertilizer and possibly utility bills (depending on your water source).
Some crops require irrigation under their foliage. Examples of these crops are garden mums, poinsettias and cyclamen. There are many ways to water underneath the foliage. Some people use a drip irrigation system such as Chapin or Netafim. Some people use an ebb and flow irrigation system, which is a table that holds water for a specified amount of time, so the plants that are placed on it will take up the water which is then drained away to prevent root rot. Other growers use a watering wand that can reach underneath the foliage of the plant, such as a 24” Dramm wand with a water breaker. The major advantage of this practice is the reduction of foliar diseases. This is due to the fact that dry leaf surfaces are not conducive environments for diseases to thrive. Another notable advantage is the reduction in water used, which leads to a reduction in algae buildup on hard surfaces and fertilizer usage. Watering underneath the foliage could also help with erosion control. Water has less distance to travel before it reaches the soil or growing media, which means it is less likely that the soil particles will be disrupted and transported away from the plant.
Manual irrigation and automated irrigation can be used to implement both overhead irrigation and irrigation below the leaf canopy. When comparing startup costs manual irrigation systems can be much cheaper than installing an automated system. This is due to the fact that manual irrigation equipment is readily available and installation requires less labor because most of the plumbing is already done for you. The problem with manual irrigation, especially if you are irrigating below the canopy, is overall costs in labor. This type of irrigation requires watering the plant one at a time. It is easy to see that your overall labor bill would be higher than if you used an automated system.
If you want to save in labor, then looking into an automated irrigation system would be a good investment for you. Automated systems include drip irrigation, ebb and flow benches as well as overhead systems such as misters and sprinklers. Automated watering systems only require one person to operate and to periodically check to see if the irrigation system is working correctly. Adding a controller to this system with solenoid valves, will allow you to program how long and at what time you want each section or “zone” to irrigate. These systems are a great way to reduce costs without skimping on quality. Automated watering systems will give the same amount of water to every plant on the system. This gives more uniformity to crops watered automatically than when using manual irrigation. The problems associated with automated watering systems are few and far between. Startup costs for automated irrigation is more expensive than manual watering. Most automated irrigation systems require additional plumbing and motorized equipment such as solenoid valves which cannot compete with the price of a hose and a watering wand. Another problem that automated watering systems could create is complacent growers. With hand watering you have to physically look at each plant you are watering, this leads to earlier detection of pests, diseases and environmental issues. Even though automated watering is less labor intensive, one should still check to see if everything is operating correctly on a regular basis and set up a weekly scouting routine for pests and diseases.
The way in which growers water their plants varies from operation to operation and also from plant to plant. Overhead irrigation is mainly used in turf grass, propagation and growing plants in inserts or plug trays. Irrigating under the foliage reduces diseases and produces healthier looking plants and lends itself for use with plants susceptible to damage and foliar diseases. One should always consider automated irrigation especially if they are looking to reduce labor costs and increase plant consistency. Now that you know some pros and cons, which watering technique is right for you?