It takes time to become proficient at watering plants. More plants die from over or under watering than from any other cause.
At the very least you will require a watering can and access to water to maintain your greenhouse plants. Many owners nowadays have a waterbutt to harvest the water from their greenhouse roof. Most greenhouses can have an internal water tank installed with the harvested water diverted into this container. This heats the water up to the ambient greenhouse temperature, reducing possible temperature shock to roots when watering.
Capillary action provides an inexpensive watering system. Using sand or a capillary mat, water is drawn up by the plants as required. The water is supplied to the sand/mat from a reservoir which is filled every few days.
A more persistent system is to use the trickle method. This takes water from an internal header tank and runs water across the compost through a porous pipe which leaks a constant supply of water onto the required area.
Full automation is achieved with the use of a computerised timing system which controls the time and periods of watering. Mains or header tank water is released through a slim pipe with drippers attached to it providing water to precise points as required. More sophisticated systems include sensors which determine when the compost is becoming too dry and automatically switch on the water.
There is no doubt that climate change is effecting temperature and rainfall. Before you purchase a watering system ask us for advice to identify the most appropriate approach for your needs.