Extending the seasons - how to make a poly or shade tunnel

5 November 2013
All of us who grow food, keep chickens or bees, milk a house cow or a goat, or keep pigs have to know a thing or two about the seasons. Here in the sub-tropics, although we recognise four seasons exist, we usually have two real seasons - hot and cold. I can't tell you how much I usually complain about the hot season. I am a cool woman, what can I say. But I've decided to enjoy every day from now on. All the sweaty days, all the clinking icy drinks, all the bugs, as well as the silent stillness of the early morning and that feeling of calm just before a tropical storm hits, I'm embracing it all. I realised that no amount of complaining will change any of what I'm complaining about and it just highlights it for myself and anyone within ear shot. Enough. I'm over it. Hot weather is the reason I notice cold weather. If it were cold all the time, I'd complain even more about that. No, from now on, I'm embracing the seasons - all two of them. Okay, I got that off my chest. :- )

If you're a gardener, you might already know that you can extend your seasons by creating microclimates. It's the backyard equivalent of dressing in a cool summer dress or pulling on a jumper and boots.

If you're in a cool climate, you can extend your season by trying to create warmth where you're trying to grow vegetables. There are a few strategies you can try. Some of them might not work but if you can get one to work, you might get an extra crop of tomatoes that might never have been. 
Some of these methods include:
  • Often growing up against a brick or stone wall will help a lot. The wall will absorb the warmth during the day and provide some protection against the cold overnight as the warmth is being released. 
  • Mulching the ground with a couple of inches of straw, hay or sugar cane will help regulate the temperature of the ground, and keep the roots warm and the soil temperature constant. 
  • If you're in a frosty area, think about growing a small hedge around the outside of your garden to stop frost rolling in. 
  • Several stakes and some hessian or heavy black plastic will provide wind protection for plants. 
  • Poly tunnels are easy to make and they'll extend your seasons like nothing else. I've drawn a diagram below that will suit shade cloth or plastic tunnels. If you're trying to keep your vegetables going, these tunnels are very portable, they can be put away at the end of the season and can be made using recycled materials. If you're using the plastic tunnel in cold weather, get extra pieces of plastic so you can cover the ends as well. 

In a warm climate, it's not heat you're wanting, it's shade and the cool air it provides.
  • If you're growing taller plants such as tomatoes, beans or cucumbers on a trellis, they love full sun, but if you look at where the shade falls on the other side of the trellis, that is where you can plant things like lettuce, spinach, Asian greens, in the shade provided by the trellis.
  • Look for afternoon shade. Many plants love it. You might find a tree or fence provides afternoon shade.
  • Make sure you mulch well - you'll need a thick layer to keep the moisture in and the soil temperature constant. It's a good idea in the hotter climates to lay wet newspaper down on the soil before adding your mulch.
  • Water your plants thoroughly and deeply, depending on how hot it is, two or three times a week.
  • If you've got good mulch down, water in the morning because the moisture will be protected and retained by the mulch. If you don't have mulch down, water in the late afternoon or evening. This will give the water a good chance to soak down to the roots and hydrate the plants overnight.
  • Plants will slowly acclimatise to heat but if your plants suffer from an unexpected very hot day, give them a good drink in the late afternoon and follow it up with a watering of seaweed tea. That will help your vegetables get over the heat shock.
  • If you're in an area that gets torrential downpours, wind and hail, a tunnel will help protect the foliage and the vegetables in your garden.
  • Tunnels to protect your plants can play an important part in your garden and extend your growing season. In a warm climate, you'll use shade cloth instead of plastic and even though it might not seem like much, the plants grow well when they're not sitting in the full sun all day.


I've looked through my photos to find the shade tunnels Hanno built here but I lost a few years of my photos and I think they may have been in that batch. I know I have a couple of photos of our tunnels on the blog somewhere, but I don't know exactly where they are. Anyhow, I've drawn a diagram (no laughing) to show what I mean. They're simple, easy and cheap to make. You'll need:
  • star peg or steel pickets - 6 for each tunnel, or 8 if they're longer.
  • three pieces of bendable poly pipe that will fit snuggly over the pegs/pickets.
  • a long piece of shade cloth or heavy duty clear plastic that covers the area you want covered.
  • enough zip ties to attach the covering to the pipe.
To make the tunnel:
  1. Attach both ends of the covering to the poly pipe using plastic zip ties. If you're using a middle bracing section, attach that with zip ties too.
  2. Lay the shade cloth out on the ground and mark where your peg will need to go in.
  3. Hammer the star pegs into the ground.
  4. Fit the ends of the plastic pipes over the pegs/pickets.
  5. Straighten it all up and if you have a flap at one end, secure it down with a couple of stones or bricks.
Make sure you make it tall enough to move around in. Getting taller star pegs should give you the right height.  Don't forget to plant what you harvest frequently near the opening, and the trellised plants along the walls.

Most of the information online if for buying tunnel kits, this is a DIY poly tunnel and here is a DIY shade tunnel, both very much like the tunnels we use here.

At the end of the season, dismantle and store the tunnels until next season. I think you'll find they make a difference to the number of months you are able to produce food.