How often and for how long to water is a good question, but there are so many variables such as air temperature, water temperature, type of growing medium to use, type of plants, how big the plants are, humidity, etc... There's simply no real right answer, we can only say that the goal is to water long enough so that the roots (and the environment for gowing) get wet, but not so long that the roots suffocate from the lack of air/oxygen. You should also water often enough so that they never dry out.
In short, the roots just need enough moisture to absorb enough water to keep the plants green. Larger plants need more moisture, because they have a lot more greenery to support. Plants that grow in dry conditions use more water than moisture-dependent vegetation. Some growing media hold moisture much better than others, so it is not necessary to water so often, etc... So just keep the growing environment moist / wet.

The water level in your hydroponic system

The water level of your hydroponic system will vary depending on the type of system in which you grow, as well as the type of growing environment you use. The type of growing environment is important because some will absorb and retain moisture better than others. In any hydroponic system, the goal is to keep the roots moist, but do not allow the stem to stay wet so that the plant develops stem rot.

Flooding and drainage systems (Ebb & Flow)

In a flooding and drainage system where the water floods the plants container below, you usually want the water level to be about 5 inches below the top of the growing environment when the system is flooded. If you use media such as rockwool, which is easily saturated, the level may be even lower. In principle, the very top of the growing medium should be almost dry to avoid stem rot, but a few inches down, where the main ball of the plant is, they should be moist. Watering:

  • Hydrocorn: 4 to 8 times a day (every 2 to 4 hours)
  • Coconut: 3 to 5 times a day (every 3 to 5 hours)
  • Rockwool: 1 to 5 times a day (once a day for every 3 hours)

Remember that these are just guidelines - do not hesitate to flood and drain beyond these limits. For example, if you grow large plants in clay stones in a hot, dry atmosphere with strong lighting and a longer day, you may need to flood and drain 9, 10 or even 15 times a day. You may need 1-2 floods at night if you have a longer dark period in the summer.


NFT systems

NFT systems typically releases a continuous thin layer of water along the bottom of a tray or a pipe. Only a millimeter or two deep. But depending on how you set up your NFT system, the type of plants and if you use a very rich growing environment, the depth of the water can vary. If the roots are able to extract enough moisture to keep the growing environment slightly moist, you're fine. However, if the growing medium is saturated, you may need to reduce the water flow through the pipe/tray or tilt it more to make the water flow faster. Or even do something to prevent the roots from blocking the flow of water through the system.

Drip systems

The depth of the water in the drip system is not really a problem, as the water has to drip/go down from the top of the growing medium to the bottom of the plant container, then back to the tank. So when it works properly, water never accumulates in the containers, the water just moistens the growing medium as it goes down.
But depending on how you designed your system and if the roots start to clog your drainage channels, you may get a buildup of water in the bottom of the container or even overflow because it can't drain properly. Make sure you check your root canal drainage lines regularly, especially when they get big, and unplug them before the roots accumulate.

  • Hydrocorn: 4 to 8 times a day (every 2 to 4 hours)
  • Coconut: 3 to 5 times a day (every 3 to 5 hours)
  • Rockwool: 1 to 5 times a day (once a day for every 3 hours)


Aquaculture systems

In aquaculture systems, the roots remain submerged 24/7, but not exactly all roots. The baskets or cubes holding the plants are hung above the water. Usually on floating styrofoam rafts or through holes in a fixed container lid. In both cases, you want the basket to be positioned so that the growing medium absorbs some moisture so that it remains slightly moist but does not become saturated. If you have enough air bubbles, this should be enough to keep the bottom of most types of growth medium moist without actually touching the water.
Underwater roots in aquaculture systems receive oxygen from all air bubbles from the air pump and air stones in two ways, so they will not suffocate. Some of the fresh air bubbles will rise through the roots until they rise to the top of the water, thus making direct contact with the roots as much as they (the more, the better). Also, when air bubbles rise, they carry oxygen molecules directly into the water itself, called "dissolved oxygen," which plants can absorb through the roots.


Aeroponic systems

The water level in the aeroponic systems is not really important. Mainly because the roots hang in the air and are never actually submerged. The timing of how often you water the roots so that they never have a chance to dry out is important in aeroponic systems.

Wick systems

With wick systems, you always want the wick to be immersed in water. Water goes to the plants through the wick. Usually some kind of felt fabric. Water never gets a chance to saturate the plant environment. But the level of moisture in it can be controlled. Just using a larger or smaller felt wick or using more than one to get even more water to fix. In this type of system, it is important to use an environment that can retain water well, such as coconut.

In our store we can offer you several different systems, which you can find here. We have several types of pumps depending on how much water your system needs. And last but not least two types of timers. The first is widely used in budget installations. It is a 24 hour timer with 15-minute cycles that you can set whether to work or not. The second is more expensive, but you have complete control over the amount of water you want to pour, as well as depending on whether it is day or night. You can set it for how much time and very important: for how long to water each day. If you want to learn more about the different types of hydroponic systems, you can check out our article "Types of hydroponic systems."