I see a lot of talk about storing rain for later use in a greenhouse... But what about letting the rain flow into the greenhouse instead of storing it?
If a small 6'x9' greenhouse has gutters, would there be more harm than good if the gutters somehow diverted water inside? I'm thinking of a pipe or hose that directs water from the gutters and brings it inside and then uses a soak/drip irrigation hose to administer it to the plants.
One of the cool features of greenhouses is that you have more control. Storing water makes more sense rather than hit or miss by rain...to include over watering. Our gardens are always going to be artificial. We humans will always be completely responsible for every little thing our plants our crops need to survive.
If you want to be successful with plants you have to be on call every day, watching, asking questions. You wouldn't know how much water your plants have gotten leaving it up to a non automatic automatic system.
Try as we might there are no easier, better and easier ways to grow plants than the basics. The basics are straight forward, tested and work. Water deeply then do not water again until the plants start having trouble pulling the water out of the soil. Do not water just to be watering.
It is akin to remaking the wheel.
Two things: Most rainwater collection systems have a diverter to allow the first few minutes of rain to NOT go into the collection barrel, or what have you. This first water tends to have a lot of dirt and dust in it. If you created a system like you describe, you may want to rig up some sort of diverter to avoid this water.
The other thing I thought of was the water pressure. Coming from the roof/gutter to a bench or floor may have more pressure than you need. If you do manage to deal with the pressure using soaker hose you may run into the water backing up into the gutter and spilling down the side of your greenhouse.
Rainwater is definitely better than tap water, IMO, but it does lose it's acidity sitting in a barrel, so there's that.
