It seems like years that I yearned for a greenhouse, dreaming of the day when I could grow my own chemical-free lettuce, tomatoes, and cucumbers year-round- avoiding the sky-high prices of out of season produce all the while enjoying flavorful, organic veggies, If only I had known ahead of time what I was in for! Before you jump into building your own, here are some greenhouse basics- what you need to know!
DIY: Greenhouse Basics
We worked together, my spouse and I, to erect this modest 8’x16′ greenhouse, reclaiming old fencing that used to contain goats in the field as simple shelves that allowed for maximum airflow.
The floor base is reclaimed limestone bricks, and paver stones laid out in a pattern created by our eldest son who reveled in the fact that he’d already designed this on his game in Minecraft and how spectacular it would look in “real life” when he was done.
In all, it took the boys about 2 hours of their time, but to me, it was a timeless moment. We filled the gaps with pebbles for drainage, because I also installed a self-watering spray system.
The area between the limestone bricks is filled with polymeric paver sand, to ensure the bricks don’t shift creating a falling hazard.
Paver sand contains a polymer that activates when it’s wet and then becomes firm when it dries. It doesn’t wash away or rinse away as play sand does.
The shelves are the perfect width to hold bags of mulch, soil, or individual plant pots. The bags you see here is a simple weed-free gardening method that is perfect for growing greens, radishes or starting larger plants such as tomatoes and bell peppers.
Choosing the Building Materials
For both the roofing and the sides we used white (& clear) corrugated panels. Corrugated roofing isn’t particularly “cheap”, but it will last 10-15 years if it’s taken care of properly.
We chose this particular material because it lets in the proper amount of light, will last, and more importantly can withstand the occasional hurricane, minor tornado, high winds, and hail that we have a tendency to receive seasonally in our area.
The installation of an automatic fan is necessary to ensure proper airflow and humidity levels.
We decided to repurpose a couple of old gutters we had lying around to plant strawberries.
Things to Consider Before Building
When I was busying myself “dreaming” of having a greenhouse… I neglected a few key points of consideration, such as:
- How difficult would it be to maintain the temperature in the building?
- How hot would it get during the day?
- At night, how cool would it be?
- What is the optimum temperature for plants to grow?
- Should the greenhouse be clear or opaque?
- What is the optimum humidity level in the greenhouse?
Well, dear reader, let’s just say in the two short months of having a greenhouse, I’ve gotten quite an education.
Temperature, Hot, Cold & In-Between
We purchased an inexpensive thermometer/ hygrometer combination, which gives both the temperature as well as the humidity level at a glance.
When choosing the greenhouse materials, take into consideration how hot your area gets. For instance, in MAY in South Carolina, it frequently hits 90°F outside, with relatively LOW humidity. What this means is that the inside temperature of the greenhouse can easily reach 128°F by 11 am, effectively cooking the plants inside.
When picking out the materials, we opted to build the sides with white corrugated panels, meaning the light filters through, but not glaringly so and the roof was alternated white and clear panels, as some vegetables require full sun. A mistake on our part, because had we the opportunity to start anew, the entire roof would be diffused without any clear panels.
Most common vegetable plants thrive best at about 75-84°F.
It didn’t make much sense to me to install an air conditioner in a greenhouse, particularly since most air conditioners also remove moisture/humidity- which is actually helpful. So, we opted to build our own air conditioner, otherwise known as a swamp cooler.
This simple device lowers the temperature to about 85°F in the greenhouse and also provides additional moisture in the air for the plants, preventing the soil from drying out too quickly.
When we first planted our seeds, it was relatively warm during the day, hitting temperatures of about 70°F, however, temperatures plummeted at night to only 36-40°F those first few days, making it difficult to keep the soil warm in the greenhouse. This was remedied with a couple of plant pots and a few tea-light candles.
Greenhouse Basics: Proper Humidity Levels
The humidity level in a greenhouse is important for several reasons, if it’s too low the soil of the plants dries out too quickly, resulting in wilted plants. If it’s too high, fungal diseases such as Botrytis or powdery mildew spread like wildfire, wiping out tender young plants.
A general rule of thumb for most seasons is a humidity level of 50-86%.
°F | Humidity |
50° | 83% |
61° | 89% |
68° | 91% |
86° | 95% |
It is important to have good airflow in the greenhouse, so be sure to install a fan in both the front and back to help circulate the air properly. If you want to have a successful greenhouse experience, keep those key questions in mind when creating your own!
