Building a greenhouse or upgrading an existing one? Wondering what greenhouse features to include? Try these ones that will make it perfect!
They are also one of the more expensive additions to your garden. So it is important not only to design the greenhouse structure properly, but also consider what accessories and features you need and want.
Some accessories and features really need to be built into the greenhouse design or be a key criteria to look for when shopping for a greenhouse kit.
You can add other greenhouse accessories later when time and funds allow as they are easily retrofitted into an existing greenhouse without much additional cost.
It’s great fun to plan out a greenhouse build and here are some ideas you can use to add elements of a greenhouse to yours.
Automatic Vent Openers
Your greenhouse needs adequate ventilation in summertime when solar gain is highest. Usually roof vents are key to good air circulation as this is where the heat accumulates (hot air rises) and needs to vent.
Unfortunately you can’t easily retrofit vents after a greenhouse is designed and built or if you don’t purchase a greenhouse that has them. So first you need to make sure that your greenhouse has enough vents based on the size.
However those vents are useless if they are not opened on hot days.
Unless you work at home you probably don’t have the time to go out to the greenhouse every morning and open the vents manually. And it’s so easy to forget and then run the risk of the temperature in the greenhouse going too high and killing plants.
Equally important is to close the vents before the greenhouse cools down too much, especially if you have very temperature sensitive plants.
So my suggestion as a wise investment is to add automatic vent openers to all of your roof vents.
I’ve covered this greenhouse accessory in an article all by itself.
They can also be added to side windows and vents as long as the windows swing open and do not slide open.
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 – 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. That works quite well especially for very large greenhouses.
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. And it will elevate them to receive more light, especially if your greenhouse has knee walls like mine has.
My benches are built to fit and I used scrap 2×4 lumber for the framing and 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 soilborne 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 should 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 or into a bucket or use drip trays under every pot.
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 or using the water hose that is conveniently located in the greenhouse.
I have now installed a drip irrigation system to my greenhouse. It still needs some tweaks to have it work optimally but it is better than nothing.
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 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.
For a good starter kit I recommend this kit:
If you mainly have in-ground or raised beds you may want to just add a couple of soaker hoses and hook them up to your hose when you need to water.
To really automate your watering add a simple irrigation timer that will turn on the water for a prescribe amount of time every day. Containers in the greenhouse especially dry out quickly. Here’s one that simply screws inline with your garden hose:
Insulated Knee Walls
Insulated knee walls are a feature that serve to limit heat gain and heat loss on parts of the greenhouse that do not need light.
This feature 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 so I have about a 3.5” wall thickness. The walls are a sandwich of cedar tongue and groove (T&G) boards on the outside, insulation (styrofoam or fibreglass) and another layer of cedar T&G boards on the inside.
Here’s what a cutaway of the kneewall looks like.
The space next to the kneewalls can’t be used for growing anything as it is too dark. However it is also under my benches, so I store soil and other materials underneath.
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. Or just use it for storage as I do.
Rain Harvesting Barrel
The greenhouse roof serves as a great rain collector. So why would I allow that water to simply go down the storm drain and pay for water to water my plants?
Therefore I have a rain barrel directly in the greenhouse that is hooked up the the rain gutter that services the greenhouse roof. The barrel is raised up off the ground by about a foot, so that I can get my watering can underneath the spout to fill it.
During even a moderate rain this barrel fills up fast – so fast that I had to add another barrel!
I mentioned in my post Vegetable Gardening On A Budget: 21 Ways To Save Money When Growing Food some of the benefits of using rainwater to water your plants. That is the main reason I collect rainwater.
But why take up the room inside a greenhouse when the barrel could instead be outside?
A dark coloured (mine is cast in a dark gray plastic) rain barrel in your greenhouse does serve 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 you always want to keep the barrel full even if you have to fill it with water from a hose like I 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.
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Temperature and Humidity Sensors
Various sensors are another very useful set of features to give 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 in the greenhouse.
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 so that you can decrease watering or spray some water on the floor if too low.
If you need to know humidity levels along with temperatures, then an all-in-one monitor is best such as this one:
Light is important for plant growth and health, especially for young seedlings. Light levels can based on the time of year, time of day and the weather. While I typically have my grow lights turning on at the same time of day 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.
A plug-in type timer with a built-in photocell will do the trick without any tricky wiring:
Now if you are a data nut and want to know everything what is happening in your greenhouse and keep historical records, this sensor when paired with a smartphone will do the trick:
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 How to Maintain Your Tools is important. When you have a convenient place to do so, it makes the chore more likely to be done.
For several years I managed without running hot water in my greenhouse, and suffered through having to wash tools and my hands in ice cold water. I finally was tired of this and hired my local plumber to add proper cold and hot water lines and I’ve so far been very happy with this addition especially in the depths of 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 shares its outside wall with my lean-to greenhouse, so just two holes needed to be drilled in the wall for the two pipes. It was an easy hookup to the existing washing machine’s supply lines.
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 all of these greenhouse accessories and features installed in my greenhouse but there are more that I’m considering such as lighting and heating.
One more feature is ventilation fans and there is a separate article on how I set that up with free energy from a solar panel.
You can get carried away with spending lots of money on features, some less useful than others. Figure out your priorities based on what you use your greenhouse for and add features as you have time, money and a need.