Using spray irrigation in a greenhouse is an ideal way to water small plants in bedding trays or seedlings quickly and evenly. Spray irrigation is ideal for smaller plants with plenty of open compost to catch the spray.
The key disadvantages are that all plants receive the same level of water which can be a problem if mixed stock is in the same greenhouse or polytunnell. Fungal disease can be a problem in particular Botrytis during the winter or early spring months.
There is a choice of overhead spray or ground level spray. The difference between the 2 is that the overhead spray has the water supply above the plants and then the sprayers spray out from above, so the sprayers are working upside down as they are hanging.
Ground level is when the supply pipe runs round the greenhouse at bench or floor level and then the sprayer is help above the plants using a stand or some other option. So these sprayers are working the correct way up and these again use a different type of head.