Greenhouse 101

You already know my article about how I built my greenhouse and I wanted to share some valuable insights about maintaining one. We can call it a Greenhouse 101 guide if you want.

I built a greenhouse for my daughter and was quite proud of it. She was thrilled and couldn’t believe how big it was and all of the things she could now plant and grow. And then -one day… the temperature spiked to 100 degrees Fahrenheit or about 38 degrees Celsius. She called me in a panic. She said the inside of the greenhouse was really hot and opening the door and window wasn’t helping.

When I got to her house, I measured the interior temperature using my iPhone. Inside it was 117 degrees F or 47 degrees C.

We found an old fan in her garage and set that up at the window, but I knew I had to find some better solutions. What follows worked but it took some planning, investment, and time.

The Critical Measures

Two things affect the health of plants in a greenhouse: temperature and humidity. My first step was to buy an electronic temperature and humidity gauge that actually had Bluetooth connectivity.

I bought it on Amazon and liked the fact that she could check what was going on in her greenhouse using her iPhone. I connected it to my iPhone as well just so I could be a backup if she was busy or out and about.

But knowing what’s going on does little to solve or alleviate temperature or humidity spikes. High temperature is the obvious villain when it comes to the health of plants, but excessive humidity can promote mold and fungal growth as well. We needed to find some solutions.

Solar Powered Fans

Most greenhouses have roof panels that can be opened to allow hot air to escape. We went one step further and installed small fans at either end of the greenhouse towards the ceiling powered by a solar panel. They run all day and into the night with a small battery charge. If it gets cold, we shut them off but during the summer they are always on.

The ideal temperature for most plants in a greenhouse is 80 degrees F or 27 degrees C. Our Bluetooth temp gauge helped us manage that. The ideal humidity for a greenhouse is 80%. That was a bit harder to manage because the fans exhausted the humidity with the heat. We knew our work had only begun.

A Rainwater Collection Barrel

The greenhouse had no gutters on the roof, but as I learned more about rainwater collection, I installed some simple gutters and drained them into a PVC reducer that I used as a funnel.

I connected other pieces of PVC to direct the rainwater into a barrel inside the greenhouse. The top of the rain barrel is open with a screen to filter out debris.

The open top helped a lot to maintain humidity. It was a black barrel that held heat in winter and encouraged some evaporation in summer. It did the trick and even with the fans blowing we maintained a humidity level of around 80%. Rarely perfect but close enough.

The rain barrel also made watering easier with a watering can but watering was still a challenge as the greenhouse flourished.

An Automatic Watering System

My daughter’s husband came across a series of hoses with water jets that could be suspended above the plants. When you hook up a hose from the house or even the rain barrel it sprays water onto the plants like they do in the produce section of grocery stores. That made watering a lot simpler and while some plants still needed to be watered with a can or hose, it reduced the amount of time we spent watering all of the plants.

What complicated things a bit was both my daughter and her husband work and sometimes they found themselves taking care of things in the greenhouse in the dark of night. Flashlights were the first solution but then we got smart.

Motion Detector Solar Lights

If there’s one thing you can count on in a greenhouse it’s a lot of sun. I came across some motion detector solar lights on Amazon and thought, hmm.

I installed two of them at both ends of the greenhouse making sure the solar panels were exposed to the most sun. They work like a champ. When you walk in at night they automatically turn on and the light is bright and fills the entire space. When you walk out they turn off after 30 seconds when they detect no motion or movement. But that led to another challenge.

My daughter noticed from her house one night that the lights in the greenhouse kept turning on and off. She wondered if it was because of temperature fluctuations or if someone was in her greenhouse. It turns out, there was something in her greenhouse: a rabbit and it had chomped up many of her young plants on flats on the bottom shelves.

Rabbit and Rodent Proofing Your Greenhouse

The rabbit invader was a new challenge and my daughter and I found a few solutions. The first was to build a small door with chicken wire across the bottom of the front door. She would leave the door open on hot days (she had to), but the small drop in door did a pretty good job of keeping the rabbit out.

Another solution was to think about what she kept on that bottom (and rabbit-accessible) shelf. Very soon young marigold plants found their way to the bottom shelf. Rabbits hate the smell of marigolds and are repelled by them. She is now growing a lot of marigolds.

Another solution for repelling rabbits and rodents is an ultra-high frequency transmitter. They’re not real expensive and you can even buy a solar-rechargeable one on Amazon. We don’t hear it but small animals do and it’s just another deterrent when unwanted visitors come in the night -or day.

It’s Working

It took a bit of investment and small amount of time, but it’s all working now. The temperature and humidity is both managed and easily measured; there’s light at night and the animals have fled the building. The result is that the greenhouse has become a pleasure and the plants are thriving.

Do you have a greenhouse? How do you keep it running smoothly? Share your tips in the comments below!

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