Making DIY Glass Cloches for Early Spring Plants

| Appropriate Technology, Gardening, Market Garden | comments | Author :


If you live in a cold or temperate climate, Spring can be a bit slow when it comes to starting seedlings. Here’s how to make DIY Glass Cloches for Early Spring Plants.

When I look at all my little seedlings, slowly putting out their first leaves in my greenhouse, all I can see right now is Summer. Masses of tomatoes, capsicums, cucumbers and leafy greens, with flowers and herbs everywhere in-between.

And then I look outside at the weather, and at the temperature gauge – both of them say that Summer will be a while yet – both the air and the soil are still pretty cold here right now.

While I’m happy to wait for some things, and make the most of early Spring (there’s more than plenty to do), I really would like to get as many veggies as I can out into the garden beds, growing big and strong, right now.

The answer to this problem? Season extenders. There’s many ways to get the jump on spring with your plants, and each technique has it’s own benefits. Cold frames, greenhouses and cloches, to name but a few.


Season Extension

Season extension is way more exciting than it sounds, and not just in the ‘have the first tomatoes on the street, impress your neighbours!’ kinda way.

For folks with a shorter growing season, season extension means an extra 1-3 months of harvest, at each end of summer, which means much more home-grown food for you. And possibly boastful amounts of early tomatoes, if that’s your thing.

Glass Cloches

Glass cloches are something I first came across in researching the 1900’s French Intensive Technique, which was a style of organic urban farming in France which inspired the market gardening philosophies of the likes of Eliot Coleman, Jean-Martin Fortier, John Jeavons and others.

At the time, I thought that using them looked like a lot of work (who wants to take on/off an entire field of individual glass plant protectors?), but now I’m working with the DIY version, I think they have a solid place in any garden that needs season extension.

The advantages of glass cloches are many:

  • If made out of sturdy glass, they can be re-used indefinitely – the ones we’re using at Melliodora are over 25 years old and going strong
  • They can easily be moved around the garden individually, as needed, unlike some other season extension systems
  • You can make them yourself, no fancy gear needed (but you might need to drink a lot of juice first)
  • If you make them out of bottles, they can’t overheat and cook your seedling as easily as some other systems, as the heat can go out the neck
  • They can be made by upcycling a waste product
  • They’re heavier than any similar plastic system, so don’t need to be secured down, and won’t blow away in a storm
  • The can be stacked for easy storage with minimal space

Making a DIY Glass Cloche

The basic ingredients you need for making DIY glass cloches from a bottle is a suitable bottle, a glass cutter, a candle and some ice.

Variations on this idea include using a diamond-bladed dropsaw, or if you’re really keen (and don’t have a glass cutter) you can use acetone (or alchohol) and string.

The variations on bottle cutting are many, but the basics are very simple:

  • Decide on break point
  • Scour bottle with glass cutter at desired break point
  • Apply heat and cold alternately, until bottle cracks at it’s weakest point, which is (hopefully) your scour mark.
  • Finish with sandpaper along break, if desired.

If you have a bunch of bottles that you wish to use for making cloches, I would HIGHLY recommend doing a bunch of non-important practice bottles first – ones that it doesn’t matter if they don’t break perfectly.

Here’s a good how-to video on three basic ways to cut bottles with minimal equipment, thought please disregard the maker’s safety standards (he has none) and possibly the music. Personally I was bopping along but then I grew up listening exclusively to John Denver so it’s been all upwards since then.

Some sandpaper to rub down the sharp edges of your successfully made cloches would be a good idea, especially if you’re gardening with little people – the edges can be pretty sharp, though nothing like jagged broken glass.

Using Glass Cloches

The glass cloches we’re using are off-cuts from a bottle + cobb wall that brings light into one of the bedrooms in the main house at Melliodora, that Dave + Su built nearly 30 years ago. They were originally sherry bottles, sourced from a friend with a big collection.

Since then, these hardy cloches are been used most years to start seedlings – that’s 28 years of service and counting… not bad at all.

In the garden this week we’re using these DIY glass cloches over brassica seedlings (Cima di Rapa + Broccoli), to get them jumping out of the ground as quickly as possible, and onto our dinner plates.

The daytime temperatures here in September are around an average of 15 degrees, and the soil is sitting at maybe 10 degrees, though it will get slowly warmer from here on in.

As most plants like their soil a bit warmer than this , and the weather here is unstable in Spring (to put things kindly), using these glass cloches has a few excellent effects:

  • Protecting the plants from possible frosts
  • Warming the air around the little seedling
  • Warming the soil directly around the plant, to aid growth
  • NOT warming the soil in the wider bed, so that weed growth is not also accelerated
  • Protecting the seedlings from scratching birds
  • Protecting the seedling from other weather extremities – wind, hail, heavy rain
  • Allows the rest of the garden bed to be watered/rained on, without having to constantly take things on and off the bed.

Once these brassicas are all happily established and growing strongly, I’ll take these cloches off and put them on whatever else needs a bump of warm air and soil, plus protection. Possibly baby peas, or something else.

And once their work is done, these cloches will be stacked back into the shed until they’re needed again to help us grow good food for another year. Waste not, want not.

Other Season Extension Systems:

Here’s some leads if you’re looking for options to extend your seasons…

As well as the following excellent books which are aimed at garden farmers, but have plenty of techniques applicable to home-scale growers too…

If you’re keen to learn to grow and live in Australia, we have a range of expert, hands-on courses from backyard growing up to organic market gardening levels…


Do you have any favourite season extension techniques?  We’d love to hear about them…

See the comments

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