- For many gardeners
growing under some kind of cover structure
is the only way to get your seeds started early
and it's the only way to extend your season
as that season comes to a close.
So in today's video we're talking with Chris
up in Vancouver, BC about the right greenhouses
or polytunnels for your garden.
- If you're in the market for a greenhouse
or maybe you are just starting to consider upgrading
from a temporary hoop tunnel
to a more permanent structure like this one,
well then this video is for you.
Hey, I'm Chris and today I wanna help break down
some of the terminology when it comes
to researching greenhouses and polytunnels
because as a shopper,
once you start researching it can be quite intimidating
once you realize all of the options out there.
The colors, materials, sizes.
Should I go with a kit or should I just DIY the whole thing?
But it doesn't need to be overwhelming or daunting.
So today we are gonna talk about the features
of these large structures and then also discuss
some differences as well as similarities
so hopefully by the end of the video
you'll have a better understanding what's what
in the greenhouse and polytunnel world
so that you can make the best decision
for your gardening needs.
And if you're wondering what the heck a polytunnel is
well, it's essentially like a greenhouse
but it is constructed differently.
It uses different materials and depending
on what you wanna use it for, it does
have slightly different functions.
Now, with these larger, there are other options
such as geodesic domes or attached greenhouses.
So there's like a building and like half of a greenhouse
is attached to a building.
And there are also all sorts of very creative ways
where people can have these enclosed areas for growing in.
But for the most part gardeners are looking
at either standalone greenhouse or polytunnels
to add to their garden.
Even though a lot of these structures
look somewhat similar when it comes
down to the material, they differ quite a bit.
So let's just start with greenhouses.
When you shop for greenhouses, you're likely going
to come across this term glazing
and all that is referring to is the material
that these panels are made from.
Now one really popular option still is glass.
It is classic, it is beautiful.
You can see right through it.
And with that, you get really great light transmission.
So the sun comes in, it goes straight to your plants
and your plants are happy.
Now, the thing with glass, you have to keep in mind
especially if you grow in a cooler climate
is that it is not very good at insulating.
So during the colder temperatures, if you have
a heater, that heat will be lost through the glass
so something to keep in mind.
Now there is the option to go for the more expensive
double paned glass.
That is great as well but the insulation properties
are still not as good as some of the other options
out there.
The other main option you're gonna see
with greenhouse glazing is this ridged
looking polycarbonate.
So this is a plastic material, (knocks)
very durable and it is very practical
especially if you have kids or if you're like me
and you have trees dropping branches on it all of the time.
It's durable, unlike glass which I always think in my head
is gonna shatter if something drops on it.
But another reason why I went with polycarbonate
for my greenhouse is because of its insulating properties.
Now this is a double wall polycarbonate
and it insulates really well.
I've got a heater and it keeps the inside quite stable
especially during those colder nights.
Now you can upgrade to a five wall polycarbonate.
It's a little bit more cost up front, but in the long run
I bet you will be saving a lot more money
when it comes to heating, especially
during those colder winter months.
So those are the two main options.
They look different.
They function slightly differently.
Pros and cons.
So really it's down to where you're growing
and also your choice of aesthetics as well.
Polytunnels are completely different
because unlike (knocks) this rigid material
that greenhouses are made of, they are covered
with this malleable polyethylene plastic sheeting.
And if you are going to use this go for a better quality
horticultural grade and a thickness of like six mil.
So the better quality and especially if you can get it
like a UV coded one, the longer it's going to last.
So with these materials, they are less expensive
but you will need to re-sheet your polytunnel
maybe every five to eight years,
depending on where you are.
And if you have a whole bunch of tears
that you need to patch up.
So with the tears, it's not a big deal.
There is special polyethylene patch tape
that you can use but it is something to keep in mind,
especially if you live in an area
where a lot of branches fall onto your structure
or if you are moving a lot of material in
and out of the structure, like in a production greenhouse.
Now when talking about the differences in the overall look
or feel or shape between greenhouses and polytunnels,
well the differences can be quite great, especially
if you are doing a greenhouse totally DIY
and you are repurposing parts,
it's going to look very unique
and probably just customized to your space.
So that's always really fun to see those creative
ideas out there.
Whereas for polytunnels you are likely only gonna run
into two main shapes.
One of the more common shapes is Quonset
which is a nice round arch.
These structures are quite robust
as they're typically made from one long tubing
bent to shape.
The other common shape is gothic arch
which is somewhat similar but it has a peaked roof
that provides more height down the middle
and also it has a steeper slope which helps
shed snow and debris.
Regardless of shape, most polytunnels
lose some height around the inside perimeter
as the poly reaches the ground.
So just keep that in mind in case you're thinking
of growing taller plants inside.
So let's talk about one of the key reasons
why gardeners look for greenhouses or polytunnels
for their property.
Well, it's because we want to control the conditions in here
whether it is for season extension
or growing food in ground year round, or like me
I wanna do some propagation in a controlled environment.
It really doesn't matter what you are looking to do.
We're talking about climate control
and depending on what structure you go with,
the methods and also the equipment involved
can vary greatly.
So for heating, we briefly
touched on that when talking about the glazing types
that you can choose for your greenhouse.
So a polycarbonate wall, especially like a double
or five wall polycarbonate is going
to insulate much better than single or double paned glass.
So if you're heating during the winter
you can retain more heat in your structure
if you have the plastic material.
Now, when we talk about polytunnels, it's slightly different
and you may be surprised by this next point.
Okay, so it's hard to imagine
a single sheet of polyethylene keeping
a big polytunnel warm during the cold months.
And that's true.
With a single sheet you can't really do much.
But with a polytunnel you have the option to do two layers
of polyethylene at the time of installation.
And the benefit of that is that you actually
attach a fan to the top of your polytunnel
and that blows air to inflate that layer.
So you get this giant bubble, essentially
like a big bubble wrapped dome, which is your polytunnel.
And that actually provides a ton of insulation
even if it is a large space.
So that is one really cool thing
about polytunnels that you can't really do
with these rigid wall greenhouses.
Now let's talk about the differences
when it comes to cooling and ventilating
your greenhouse or polytunnel because it is quite different.
So in these smaller greenhouses
especially the residential sized ones,
these rely on passive ventilation.
So hot air rises and that's why you get roof vents
on these structures and they automatically open
with these automatic vent openers
and they are actually quite low tech.
If you look into it it's pretty cool how the mechanism works
but this is usually what you're going
to see see in a greenhouse.
And of course, if you want more ventilation
you can have it customized.
You can have like side panels that open up
in the same manner.
Of course you can open the front door
and if you can have a back door as well
and that way you get a lot of fresh air moving
through the structure.
Polytunnels are slightly different.
Unlike greenhouse houses,
polytunnels will not have these roof vents
because remember polytunnels are made
from soft plastic sheeting.
So unless you're looking at a very large structure
where you can add some framing to it and install roof vents,
you're likely going to have to rely on the front door
and some back opening, whether it's a door
or some louvred opening to push air through the structure.
Now what's really cool about polytunnels
is that you can have this added side feature
to the structure
for what's called a side roll up.
So with the poly that drapes on either side,
you can have it kind of like free floating
and not fully attached to the base of the structure.
And that will allow you to attach this long pole
with a handle to roll up the plastic
so that you can get really great airflow at the bottom.
So not only is this great with ventilation,
you can actually access the polytunnel from the outside
and this is super helpful if you are actually growing
in ground beds, or if you have containers
along the wall and you want to water them
or harvest from them during the main season
it's a really nifty feature that is pretty specific
to polytunnels.
Before we start talking about similarities
if you are wondering if one costs more than the other,
generally greenhouses will cost more based on the materials.
So if you're looking for a more economical option,
polytunnels are great.
Material costs are lower and also the initial setup
takes less time, less labor.
And also if you inflate those walls,
you could be saving a lot of money
in the long run in a cooler climate.
Chances are whatever you do in a greenhouse
you can do in a polytunnel and vice versa.
It really depends on, you know, what you want
out of the space and what you wanna do.
So just think of them as very similar structures
even though we talked about a whole bunch of differences
and one of these similarities starts with the foundation.
If you're thinking of growing plants in ground
you'll likely have large areas of soil
for your growing beds.
But if you're looking for a flexible,
multi-use space with a potting bench, shelves
and possibly a spot to sit and relax
some popular foundation options are 3/4 crushed gravel,
pavers, non-woven fabric over a compacted base
or a combination of all of these materials.
So for heating, cooling, and shade
there are a number of similarities regardless
of the type of structure that you have.
So I've got a little heater here
that's plugged into the house.
This is one 110 volt.
If you have a larger structure or you want more heat
you may need the help of an electrician
to help up that juice.
And when it comes to cooling, we talked about
a whole bunch of differences but at its core,
you just want to open windows, open whatever you have
so that you can allow for a lot of ventilation
to push a lot of the hot air out.
And if you want to keep the structure cool,
shade cloth works really well.
So it's a horticultural fabric,
it comes in different weaves to allow different percentages
of light to come in.
So if you wanna block out a lot of light
that will help keep the temperatures cooler.
Let's not forget to talk about
air circulation.
So for these large enclosed spaces, we want to make sure
that there are no pockets of overly cold,
hot or moist areas either around plants,
under plants or just tucked away in a corner
because that can lead to all sorts of pests
and disease issues and also general mold and algae issues
which you don't want to deal with
in a space that you want to keep clean.
So all you need are some small fans for a small space.
So I've got two in my greenhouse.
If you have a larger space you may want a couple
of those larger ones that you mount onto the roof
to really help circulate fresh air throughout the structure.
If right now you're thinking, oh my gosh
that's a lot of information.
I still don't know if I want a greenhouse,
a polytunnel or something else or nothing at all,
and that's okay.
So my tip right now is to sit, pen and paper,
write down some gardening activities
that you see yourself doing in a space like this.
If you are having a hard time brainstorming some ideas,
maybe this is not the right fit for you.
Maybe those low temporary hoop tunnels
are the perfect fit for what you do in the garden
and there's nothing wrong with that.
But for those people who are interested to know more
about greenhouses and the whole shopping journey,
stay tuned because in the future I am really wanting
to do a video on how to help you visualize a greenhouse
or polytunnel in your space and how to orient it
and really assess your property.
So thanks for watching
and stay tuned for that next video.
- I have to confess, I kind of want a greenhouse
or a polytunnel now.
Here in the backyard of The Epic Homestead,
hopefully this video was helpful to you.
I'm gonna keep my seed starting going,
more stuff coming really soon.
Good luck in the garden and keep on growing.