Dramm mist propagation systems are designed to evenly distribute the right amount of water on liners of seedlings or cuttings. Providing the right flow and droplet size is important to ensure that the media remains moist during rooting. The timing of these mist cycles is just as important. Using the right controller to ensure that the misting cycles are timed correctly can have a great impact on your production.
Starting with the basics: a good misting controller should have great flexibility in the duration and interval of the mist cycles. When choosing a misting controller, look at the minimum duration available. When germinating seed, propagating in smaller cells or simply need less water, shorter duration times are important. While many clocks on the market have a minimum duration of 5 seconds or greater, some have shorter durations available to allow for reduced moisture.
Minimum intervals can also have an impact. Shorter intervals allow for more frequent misting cycles. This is important if you want to increase humidity without wetting too much. The same amount of moisture in a space can be achieved with 10 second durations and 5 minute intervals as 5 second durations and 2.5 minute intervals. In each case, the same amount of water is used, but with shorter misting durations, more is able to evaporate as a mist rather than causing over saturation of the air and wetting the plants and media.
The Dramm ii ri Controller is a low-cost, single valve controller that is great for one or two benches or temporary propagation areas. Programmed via a Bluetooth-connected app on your phone, the ii ri Controller can be used as an irrigation OR a misting controller. While irrigation controllers start on a specific time, misting controllers operate on a cycle. The battery-operated ii ri has a short minimum duration of 3 seconds and a minimum interval of 10 seconds.
Solenoid choice will also impact these cycles. Many solenoids are slower to react, requiring more than 1 second to close, especially with lower flow misting systems. This can turn a 5 second duration into 6.5 seconds, increasing the total water volume unintentionally. Faster acting solenoid valves close much faster, turning off misters quickly and preventing larger droplets that occur with declining water pressure as slower valves close. Dramm offers a fast-acting solenoid that closes in milliseconds.
Advanced irrigation controllers that are often part of a complete climate control system, can utilize humidity, temperature and light to determine the need for misting. By looking at light accumulation or calculating VPD, these controllers can provide water when the plants need it. Dramm often recommends that growers with these systems and the training to use them, utilize them for their misting and irrigation control. However, not everyone has sophisticated climate control or the skill to fully utilize their features.
The Dramm MistTime offers short minimum durations and intervals for misting, but also can incorporate temperature and a programmable daily misting curve to increase or decrease frequency of mist throughout the day.
Using time buckets, the MistTime can increase and decrease misting frequency to match the common climate changes in the greenhouse throughout the day. For example, a grower could set up the misting frequency in six different buckets as follows:
- 12:01am – 6:00am: mist once every 2 hours.
- 6:01am – 8:00am: mist once every 1 hour.
- 8:01am – 10:00am: mist once every 30 minutes.
- 10:01am – 2:00pm: mist once every 15 minutes.
- 2:01pm – 5:00pm: mist once every 45 minutes.
- 5:01pm -11:59pm: mist once every 2 hours.
This curve approximates the general increase in moisture needs during propagation that would occur as temperature and light increase in the greenhouse. Again, by increasing frequency and not the duration, better control of the moisture levels can be achieved by preventing oversaturation of the media and the air.
These curves can be further enhanced by adding temperature as in input. Using the optional temperature sensor, the MistTime can adjust frequency further as temperature rises and falls, giving greater flexibility to the misting cycles.
As you prepare for the next season, Dramm can help you with the optimum misting system for your propagation, combining accurate nozzles, complete system designand the right control to maximize your rooting and germination. Contact your Dramm representative for help designing your next propagation system.
