Supplying water to the plants in the greenhouse is one of the main functions of any greenhouse. How that water reaches the plants, and how well the process is managed will determine the success or failure of your greenhouse.
Know your plants
Of course, some plants need more water and some plants need less. Cacti hardly need any water. Tropical ferns and orchids on the other hand, can be overwatered and still thrive. Most plants will lie somewhere in the middle of the range.
So, before you setup your greenhouse water system, you should already have in mind what kind of plants you will be growing there. This will help you to plan your watering system, whether you will be doing it yourself, or whether you need an automated sprinkler-type system.
Automated watering systems can take on the form of sprinkler systems that can spray water at set intervals, or simply a soaker hose system that slowly leaks out water into the soil. The type to be installed depends on the types of plants you plan to grow.
Having a tap or long hose from the house would be a lot easier than watering with a can. So, having an internal faucet inside the greenhouse is a good solution in the short term, as you can water all the plants without having to open the greenhouse door by going in and out.
It is not difficult to build a piping system to your greenhouse; most of it is merely attaching inexpensive standard PVC pipes for a few dozen yards, and then installing the couplers, valves and faucets. Standard-sized pipes should supply plenty of water for any greenhouse, unless it is a very large one. To keep the pipes safe, it is recommended to dig a trench and then bury the pipes underground. Also, don’t forget to dig a proper drainage/plumbing system for the water runoff from the greenhouse.
Ventilation and maintenance
Part of your construction budget should go into building a decent drainage/plumbing system for greenhouse; it should connect to a proper drain and not let the water to just flow out to the grass. Remember that all these piping connections will require maintenance from time to time. Temperature changes can crack pipes and hoses over time.
If you are installing a sprinkler system, especially an overhead one, the interior of the greenhouse is going to get wet all the time, so makes sure the tables, benches and the interior paint is able to withstand continuous moisture every day.
The plants will also be releasing moisture from transpiration, and all that humidity needs to be released via a good ventilation system. Mildew and algae buildup may occur if the humidity levels are constantly high. Either way, you have to be prepared to clean the walls and roof periodically.
Ventilation problems can be solved by having a gap or holes at the roof, and installing a fan. This will not totally prevent the occurrence of algae or mildew, but you will not need to clean the greenhouse so often if you are more careful with the watering system; only the plants should get wet, not the walls.