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The Ebb And Flow Method Of Cannabis Cultivation

Hydroponic systems have become increasingly popular among cannabis growers in recent years. Several different techniques and methods are being used to great effect. Among the cheapest, easiest, and most efficient of these is ebb and flow, which differs from other hydroponic solutions. It does not continually submerge plants’ roots in water but instead alternates between wet and dry phases.

What Is Ebb And Flow?

Also known as flood and drain, ebb and flow is a system that periodically supplies plants’ roots with nutrient-rich water. Then, allowing this drain away so that the roots can become bathed in oxygen. By employing this “feast and fast” model, ebb and flow ensure that plants receive all the nutrients they need. Allowing for sufficient airflow to prevent mould or other pathogens from setting in.

Several different design variations have been developed. Yet, the most simple involves placing plants in pots containing a typical hydroponic growing medium. Rockwool, clay pebbles, coco coir, or lava rock all work. The function of this medium is to anchor the roots of each plant in place. Draining slowly once water is added.

These potted plants are then placed in a growing tray, which sits above a separate tank containing nutrient-rich water. A submerged pump forces this water up into the growing tray at regular intervals, where it enters through holes in each pot and floods the plants’ roots. When the pump is switched off, the water drains back into the reservoir below. Leaving the roots dry once again – hence the name, “ebb and flow.”

Such a system ensures that plants grow strong, healthy roots. Ensuring they maximize their water intake, nutrients, and oxygen. Plants starved of water and nutrients during the dry phase cause them to drink in as much as they can once they receive their periodical “feast.” Likewise, the lack of oxygen available during the flooding phase leaves plants gasping for air and primed to suck up as much of this as they can see once the water drains away and breathing becomes possible again.

The Advantages And Disadvantages Of Ebb And Flow

Compared to other hydroponic systems, ebb and flow is pretty easy to set up and low maintenance,. The whole process can be automated with little need for any input from the grower. By setting the pump to a timer, the amount of work required to keep the whole thing running smoothly is minimised.

The lack of large or expensive equipment required also makes the ebb and flow an excellent option for those with space or budget restrictions.

It’s also pretty easy to control certain variables like temperature and pH, which can be achieved simply by heating or cooling the water in your tank or adding acidic or alkaline supplements. Unlike other growing methods, ebb and flow negate the need for sophisticated systems to carefully manage the growing environment.

ebb and flow
Image source

However, it’s absolutely essential to set the system up correctly, as any malfunctions can destroy your entire crop. Insufficient drainage, for instance, can provide the perfect conditions for mould to become established. At the same time, any nutrient deficiencies in your water supply can have a detrimental effect on the growth of your plants.

Things To Consider With Ebb And Flow

Some variables need to be determined before getting started with ebb and flow, with the first of these being the growing medium that plants are to be rooted in. As previously mentioned, there are several different hydroponic media to choose from. When doing so, you’ll want to consider the speed at which each of these materials drains.

Ideally, you should choose a medium that drains well but slowly, thereby ensuring that some moisture is retained during the ‘flow’ stage, but not enough to give pathogens a chance to thrive.

The number of floods to conduct each day is also an important variable and will depend partially on which growing medium you decide upon and the climate in which you are cultivating your plants. In cooler environments, or when using slow-draining growing media such as Rockwool, two floods per day will typically be sufficient. However, this may need to be increased to three or four per day in warmer climates or when plants are rooted in fast-draining materials.

Generally, each ebb and flow cycle should last half an hour, with the pump activated for the first fifteen minutes – thus allowing roots to become flooded – followed by fifteen minutes of drainage once the pump is switched off.

Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

Ben Taub