Greenhouse – Watering

Q: We need your help on the timing and frequency of our new water sprinkler system for our greenhouse. My husband is in the process of installing it. We need to know how often and how long to set the water to come on. We have different thoughts about this. Can you help?

He built the greenhouse from a kit about 4 years ago. It leans away from our brick house, facing south. It is about 10 ft long by 7 ft wide. We have lots of plants – several varieties of ferns, bromeliads, money tree, bougainvillea, impatiens, aloe vera, begonias, sedum, orchids, etc

The orchids especially love the humidity and light levels – we have about 10 – 15 orchids now – and there is always one or two in bloom. We have a small heater and the temperature never gets below 50 degrees. We have gro-lights that turn on automatically when it is dark for a few extra hours of light.

The plants and a couple of cats love it in there!

A: With this many different plants so close together, it’s almost impossible to water them all properly with a mist or spray system. Since your husband is so handy. talk to him about changing the spray system to a dripper system.

He can buy the drippers and the thin spaghetti tubing that supplies water to them at a home improvement store or online. I’ve used both Charley’s Greenhouse and Home Harvest Garden Supply .

Set up three main supply lines along the benches. One will be for “low water plants, one for “medium water” plants and one for “high water” plants. Each one will need a valve controlled by a timer.

You’ll need lots of drippers, one for each plant. I recommend you get only the 1 gallon per hour, pressure compensating drippers,

Insert several spaghetti tubes, each with a dripper on the end, into the “low water” supply line. Run it to one of your plants that doesn’t need much water each week. Put the dripper in the center of the pot and anchor it in place with a rock or a bit of coathanger wire.

Run more drippers from the corresponding supply lines to the “medium water” and “high water” plants.

When it’s all done, you can set the timer on each supply line to apply water as needed to the plants that require similar amounts of water. Orchids might need watering twice per week but the poinsettia I see in your photo might need water only once per week.

Your husband will be tempted to run a single supply line and then use drippers that emit different amounts of water in an hour. Don’t let him do this: it is MUCH more complicated to supply the right amount of water that way than it is to have three supply lines.

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