You can add many features to a greenhouse to make it a perfect place for raising seedlings, overwintering delicate plants and providing a hot environment for heat-loving plants. There are some features though that are in my opinion essential for success and comfort.
You will need to consider some of these features early on when you are still choosing which greenhouse you are going to build or purchase, as you may find it difficult to add them after the greenhouse is built. Other features are easy to add later when time and funds allow.
Automatic vent openers
It is important that your greenhouse has adequate roof vents for good air circulation especially in summertime. However you probably don’t have the time to go out to the greenhouse every morning and open the vents manually. And it is easy to forget and then your run the risk of the temperature in the greenhouse going too high.
So the solution here is to add automatic vent openers to all of your roof vents. They can also be added to side windows so long they swing open and not slide.
Electric automatic vent openers use an electric motor to open the windows in the morning and close them again at night. They require an external temperature sensor to tell them what to do. And you do have to rely on a power supply, whether it be batteries, solar cell or line power to power the motor.
Gas automatic vent openers rely on a expandable gas that expands when heated and contracts when cooled. They do not require an external temperature sensor and are adjusted with a thumbscrew to set the temperature at which they open and close. They are a bit more reliable than an electric system. These are what I have on my three roof vents.
Caution: vent openers do fail so always ensure you have at least two to three vents so that if one opener fails your greenhouse will still vent at least a little bit. This happened to me with one of my three – since fixed once I secured the adjustment thumbscrew from turning by itself.
Benches with ventilation
Some greenhouses simply have in ground beds or raised beds with paths in between just like a garden outside.
However if you are growing plants in pots or using your greenhouse to start seeds you will need a bench to put these on to make the plants easier to tend to for watering, weeding and harvesting.
My benches are built to fit and I used scrap 2×4 lumber for the framing and some stained cedar for the tops. Always provide gaps between the top boards for ventilation and drainage. These also came in handy when I started to experiment with a drip irrigation system as it allowed the 1/4” supply line to the drip emitters to stick through the bench tops.
Make sure to clean the bench tops regularly to avoid mildew and soil-bourne diseases. And you will find the underside of the bench tops will usually become home to spiders, their stash of eggs and their webs so periodically you could vacuum underneath – try to keep some of the spiders though as they do eat pests.
You can use the space underneath the benches to store pots, soil, fertilizer, flats, etc. However when you water expect these to get wet from overflow so you may want to install some type of rigid material underneath the bench tops to funnel water to the sides at least.
Drip irrigation system
I never had an irrigation system in my greenhouse. I usually watered everything by hand either filling up a watering can with water from my rain barrel (see below for more info) or using the water hose that is conveniently located in the greenhouse.
Just before going on a trip in early June I put in a rudimentary system. However I have yet to use it as I have a few leaks and I found that the drip emitters were filling some pots too fast. It was easier to water by hand as I always have done.
However before next summer I will have another look at it and perhaps design it better.
If you want to add a drip irrigation system to your greenhouse, there are many kits available which contain everything you need. If you mainly have pots in the greenhouse like I have think about flexibility. You’ll want to have a header hose go around the perimeter of the greenhouse and then have the smaller supply lines branch off (with extra length for changes) at convenient locations.
If you have mainly beds you may want to just add a couple of soaker hoses and hook them up to your hose when you need to water.
Insulated knee walls
Insulated knee walls serve to limit heat gain and heat loss on parts of the greenhouse that do not need light.
This could be retrofitted to an existing greenhouse but is easier and less expensive to add when the greenhouse is being designed and built.
My kneewalls are built from 2×4’s laid flat so I have about a 3.5” wall thickness. The walls are a sandwich of cedar tongue and groove boards, insulation (styrofoam or fibreglass) and another layer of cedar T&G boards.
The space next to the kneewalls can’t be used for growing anything as it is too dark. It is also under my benches. So I store soil and other materials underneath the benches next to the knee walls.
If you have raised beds or plant directly in the ground of the greenhouse you will find that sunlight in summer will reach most parts of the greenhouse floor except right beside the kneewall but that may be a good location for shade tolerant plants such as greens.
The greenhouse roof serves as a great rain collector. So why would I allow that water to simply go down the storm drain? Therefore I have a rain barrel directly in the greenhouse that is hooked up the the rain gutter that services the greenhouse roof.
During even a moderate rain this barrel fills up fast – so fast that I need to come up with a better overflow to direct the excess water once the barrel is full to the floor drain.
The barrel is raised up off the ground by a good foot or so so that I can get my watering can underneath the spout to fill it.
I mentioned in my post 6 Ways to Save Money in your Garden some of the benefits of using rainwater to water your plants.
A dark coloured (mine is cast in a dark gray plastic) rain barrel in your greenhouse serves another purpose. The water in the barrel will heat up during the daytime when the sun is shining on it and release that heat slowly in the nighttime to keep the greenhouse warmer. So always keep the barrel full even if you have to fill it with water from a hose like I have to do during our dry summers.
Warning: some jurisdictions have strict laws about collecting rainwater and actually ban this practice. So before starting to collect rainwater make sure you are not breaking any laws.
This is the most useful feature in my opinion as it gives you a good idea of the greenhouse environment at any time during the day. And the more sophisticated sensors can also send signals to a central computer that then opens vent windows, runs fans and even waters your plants.
Temperature is very useful to know as it will tell you if you have adequate ventilation, the right time to start planting seeds, and if you need to add supplemental heat to ward off very cold temperatures. I use a simple wireless thermometer that is in my kitchen and shows house temperature and greenhouse temperature. It has the added benefit of recording the min and max temperatures so I know if it is getting too hot or too cold.
Humidity when it gets too high in your greenhouse can cause mildew and rot issues. Sensors can detect when the humidity is too high and open vents and turn on fans. Or a simple sensor will record humidity so you can see if it is too high or too low.
Light is important for plant growth and health. Light levels can fluctuate based on the time of year, time of day and the weather. While I typically have my growlights turning on at the same time via a simple electric timer, you can also get light sensors that will turn on the light only when it is dark enough. Sometimes these sensors are built into the lights.
Sink with tap and running cold (and hot) water
This could be considered a luxury but for me it is essential. Washing tools as I mentioned in my post on How to Maintain Your Tools is important and having a convenient place to do so makes the chore more likely to be done.
For several years I managed without running hot water but this past spring I had a plumber add proper cold and hot water lines and I’ve so far been very happy with this addition and will see it’s benefits even more this winter.
Whether you hire a plumber or do-it-yourself make sure it is in accordance with local building codes. For a free-standing greenhouse in the middle of the garden this may be more expensive as there is more distance to the nearest water supply, especially the hot water. My plumber had it easy as my laundry room is directly behind my greenhouse so just two holes needed to be drilled in the exterior house wall (which is inside the leanto greenhouse).
As a temporary solution though you could hook up a hose from a water bib to your sink and use a large container as a drain container so long as you remember to empty it regularly. You could also have a small electric under-sink heater installed in lieu of a dedicated hot water line if you have an electric supply to your greenhouse.
Warning: if your greenhouse temperature has any chance of going below freezing you’ll want to ensure that all the pipes are insulated and that you can turn off the water supply from inside the house when it gets too cold.
I currently have these features installed in my greenhouse but there are more that I’m considering such as fans, lighting and heating. As I add them to my greenhouse I will share my experiences with them and provide tips.
Do you have any features that you consider must haves for your greenhouse? Please share in the comments below.