Simple Greenhouse Irrigation


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There are several methods for feeding a greenhouse crop; hand watering, sprinklers, sub-irrigation, and drip irrigation to name a few. These systems can be considered closed or open depending on how the deliver and replenish their reservoirs. A closed irrigation system collects any run off and non-absorbed nutrient solution pumping it back into the reservoir to be reused (ex. hydroponics). An open system allows the solution to be absorbed past the roots and into the environment (ex. plants planted in the ground).

Depending on the size of your crop hand watering can be extremely inefficient as labor can be expensive, watering can be inconsistent, and nutrients can end up wasted. When hand watering is not economical, it is time to consider an automated irrigation system.

An effective irrigation system will deliver the right amount of water/nutrients to all plants in the irrigation zone, losing the least amount of water through leaching and run off. For container gardening, one of the simplest and most effective irrigation systems is a top-down (drip) irrigation system.

Drip irrigation
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Drip irrigation is a hydroponic or soil technique which relies on a regulated flow of nutrient solution to the plants. It is a low maintenance, efficient, productive, and affordable system that is recommended for both beginners and advanced growers. The drip system needs to be under pressure, requiring either a water pump or gravity feed approach. The water flow is usually set on timers with the goal of letting the plant roots aerate between nutrient cycles.

Some of pros of a drip irrigation systems include: water conservation, flow control, limited erosion or nutrient run off, easily automated, and low cost. Some cons include: clogged drip nozzles, clogged filters, line punctures, system failure, and potential trip hazards. Here is a list of some advantages and disadvantages for greenhouse drip irrigation systems.

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Overhead sprinkling can also be used for greenhouse container gardening. In this type of system irrigation pipe is routed above or next to the plants, supplied with nozzles which can vary in spray ranges. These can cover a large grow area, have a fairly long lifespan, and provide uniform watering for the greenhouse. Some Compared to drip irrigation, sprinklers come with a higher potential for water loss through evaporation, potentially higher cost, and should not be used on crops susceptible to foliar diseases. Here is a small list of pros and cons for sprinkler systems.

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Another potential irrigation system is an ebb and flow (also called ebb and flood and flood drain) system. The name describes two phases of the tide or any similar movement of water. The ebb  is the outgoing phase, when the tide drains away from the shore; and the flow is the incoming phase when water rises again. This technique waters from the ground up (sub-irrigation) where the plants’ roots are in direct contact with the nutrient solution.

Some of the pros of these systems is that they can be easy to build and use, affordable, and provide heavy loads of nutrient rich water. Some of the cons include: high risk of over-watering,risk of system failure, unstable pH levels, and potential plant toxicity/deficiency. Here you can find a complete list of pros and cons for a hydroponic ebb and flow system.

There are various irrigation systems for growing cannabis in a greenhouse or warehouse. Commonly these include drip irrigation,hydroponic flood benches, and trough benches. Here is a list of a handful of other irrigation techniques for cannabis, mostly geared for smaller grow ops. Here is a thorough article from HighTimes on best indoor marijuana growing set ups.

An irrigation system should be designed in conjunction with a nutrient management system for maximizing the production yield of your crop. There are a ton of different irrigation systems on the market, and this post only named a few of the most popular choices. It is important to note the pros and cons of each system, especially how it relates to your specific crop. This combined with proper nutrients and a greenhouse can help you maximize your yields.

Do you have any experience with this topic? What is your favorite irrigation system? Please leave your thoughts in the comment section below.

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